Starlix

Ollivier Laccourreye, MD

• Professor, Department of Otorhinolaryngology?ead and Neck Surgery
• University Descartes-Paris V
• H?pital Europ?en Georges Pompidou
• Member, Acad?mie Nationale de Chirurgie
• Paris, France

Primary neoplasms such as diffusely infiltrating astrocytoma usually involve white matter or white matter plus cortex joint infection hiv discount starlix 120 mg buy on-line. Acute cerebral ischemia-infarction occurs in a typical vascular distribution hiv infection oral route starlix 120mg buy low price, involving both the cortex and white matter hiv infection rates thailand starlix 120mg free shipping. Postictal edema is transient but generally more widespread antiviral injection for shingles starlix 120mg purchase amex, often involving most or all of the hemispheric cortex hiv infection eye splash order starlix 120 mg online. Temporal lobe confluent hyperintensities with patchy foci of marked hypointensity are consistent with encephalomalacia and chronic hemorrhage. Similar findings were present in the insular cortex and cingulate gyri (not shown). The median interval between transplantation and onset of neurologic symptoms is 3 weeks. Patients typically present with altered mental status, shortterm memory loss, and seizures. Note edema and mass effect, seen as hyperintensity in both cerebellar hemispheres. Postictal hippocampal hyperemia is transient, and extrahippocampal involvement is absent. The most common nonepidemic viral encephalitis, herpes encephalitis, was discussed earlier. Miscellaneous Acute Viral Encephalitides Viral encephalitis is a medical emergency. Timely, accurate diagnosis and prompt therapy can improve survival and reduce the likelihood of brain injury. Ischemic or hemorrhagic strokes, aneurysms, subarachnoid and parenchymal hemorrhages, arterial ectasias, and dissections have all been described. Meningitis is the most frequent overall manifestation (50% of cases) and the most common clinical presentation in immunocompetent patients (90%). Transmission increases in warmer months; in the Northern hemispheres, peak activity is from July through October. Hemorrhage and enhancement are generally absent, helping differentiate rabies from Japanese encephalitis and other viral encephalitides. Onset of neurologic deterioration occurs a few days to a week after the first signs of influenza infection. The morbidity and mortality are particularly impressive among patients with trisomy 21 (12-68). Nearly 55,000 deaths due to rabies encephalitis occur annually, 99% of them in Asia and Africa. The virus is abundant in the saliva of the infected animal and is deposited in bite wounds. Human rabies encephalitis is a rapidly fulminant disease that is invariably fatal once clinical symptoms become evident. The history and clinical presentation are highly suggestive, but the definitive diagnosis requires laboratory confirmation of rabies antigen or rabies antibodies or isolation of the virus from biologic samples. Periventricular white matter, cerebellar, and spinal cord involvement has been reported in some cases. The midbrain, pons, cerebellum, and deep cerebral white matter are frequently involved. Miscellaneous Infectious Viral Encephalitides A host of other viral encephalitides have been identified. Arthropod-borne (ticks and mosquitoes) viruses represent an underappreciated cause of encephalitis in older pediatric patients and adults. In this section, we briefly consider two chronic encephalitides: the measles reactivation syndrome called subacute sclerosing panencephalitis and Rasmussen encephalitis. Measles virus disproportionately affects children in regions with low measles vaccination rates. Symptom onset is often insidious, with behavioral and cognitive deterioration, myoclonic seizures, and progressive motor impairment. More than 95% of patients die within 5 years, most within 1-6 months after symptom onset. Diffuse atrophy with ventricular and sulcal enlargement ensues as the disease progresses. Biopsy findings are nonspecific, with leptomeningeal and perivascular lymphocytic infiltrates, microglial nodules, neuronal loss, and gliosis. Patients are clinically normal until seizures begin, usually between the ages of 14 months and 14 years. Neurologic deficits are progressive, and the seizures often become medically refractory. Treatment options have included immunomodulatory therapy, focal cortical resection, and functional hemispherectomy. Infection, Inflammation, and Demyelinating Diseases 376 Selected References Congenital Infections Lee J: Malformations of cortical development: genetic mechanisms and diagnostic approach. Immigration and widespread travel have resulted in formerly exotic "tropical diseases" such as neurocysticercosis and other parasitic infections becoming commonplace. We first turn our attention to mycobacterial infections, focusing primarily on tuberculosis. They are divided into three main groups, each with a different signature disease: (1) Mycobacterium tuberculosis (tuberculosis), (2) nontuberculous mycobacteria ("atypical" mycobacterial spectrum infections), and (3) M. Each group has different pathologic features, clinical manifestations, and imaging findings. We follow with a brief review of nontuberculous mycobacterial infection and its rare manifestations in the head and neck. Neurotuberculosis is secondary to hematogeneous spread from extracranial infection, most frequently in the lungs. Rupture of a Rich Infection, Inflammation, and Demyelinating Diseases 378 focus into the subarachnoid space causes meningitis, vasculitis, and occasionally encephalitis. The majority occur in the cerebral hemispheres, especially the frontal and parietal lobes and basal ganglia. An inflammatory reaction ("exudate") with a variable admixture of exudative, proliferative, and necrotizing components in the subarachnoid cisterns is the typical finding (13-1). Note the vessel irregularity and early basal ganglia ischemia related to arteritis. The suprasellar/chiasmatic region, ambient cisterns, and interpeduncular fossa are most commonly involved (13-3). Tuberculomas have a creamy, cheese-like, necrotic center surrounded by a grayish granulomatous rim (13-4). Edema, perivascular infiltrates, and microglial reaction are common in brain tissue immediately under the tuberculous exudate. The inflammatory exudate encases major vessels and their perforating branches, invading vessel walls and causing a true panarteritis (sometimes called "endarteritis obliterans"). Mature tuberculomas demonstrate central caseating necrosis with a surrounding capsule that contains fibroblasts, multinucleated giant cells (generally Langerhans type), epithelioid histiocytes, plasma cells, and lymphocytes. The majority of survivors have long-term morbidity with seizures, mental retardation, neurologic deficits, and even paralysis. The highest prevalence is in Southeast Asia, which accounts for one-third of all cases. One of the most common "brain tumors" in endemic countries is tuberculoma, which accounts for 10-30% of all brain parenchymal masses. Presentation varies from fever and headache with mild meningismus to confusion, lethargy, seizures, and coma. Patients who deteriorate during treatment often develop new hydrocephalus, infarcts, exudates, or tuberculomas. Tuberculosis and Fungal, Parasitic, and Other Infections enhancement (pachymeningitis) with or without involvement of the underlying subarachnoid spaces may occur but is uncommon. Tuberculous exudates often extend into the brain parenchyma along the perivascular spaces, causing a meningoencephalitis. The affected cranial nerves appear thickened and enhance intensely on postcontrast images. Liquefied areas may be T2 hyperintense with a hypointense rim and resemble abscess (13-10A). Enhancement is variable, ranging from small punctate foci to multiple rimenhancing lesions. Mild to moderate round or lobulated ring-like enhancement around a nonenhancing center is the most typical pattern (139B) (13-10B). A large lipid peak with absence of other metabolites such as amino acids and succinate is seen in 85-90% of cases (13-10C). They are often multiloculated, are typically larger than granulomas (> 3 cm), and can resemble neoplasm. A ring-enhancing multiloculated lesion or multiple separate lesions is the typical finding on T1 C+ images. Tuberculomas can also resemble pyogenic abscesses or neoplasms (13-11) (13-12) (13-13). Pathology disclosed granulomas with large, multifocal areas of coalescing necrosis. Human disease is usually caused by environmental exposure, not human-to-human spread. Disseminated systemic infections are primarily seen in immunocompromised patients. Children younger than 5 years and immunocompromised adults are typically affected. Most patients are afebrile and present with a painless, slowly enlarging submandibular or preauricular mass. Tuberculosis and Fungal, Parasitic, and Other Infections Inflammatory changes in the surrounding tissues are minimal or absent. The major differential diagnosis of nontuberculous cervical lymphadenitis is suppurative lymphadenopathy. Tuberculosis causes 95% of cervical lymphadenitis cases in adults but only 8% in children. Imaging studies demonstrate multiple enlarged posterior triangle and internal jugular nodes. Cat scratch disease presents 1-2 weeks following the incident and is seen as reactive adenopathy in regional nodes draining the lesion. Second branchial cleft cyst can mimic a cystic lymph node but is located between the submandibular gland and sternocleidomastoid muscle. Reported findings are perivascular granulomatous inflammation with multiple enhancing parenchymal lesions on T1 C+ scans. At biopsy, mycobacterial pseudotumors contain sheets of epithelioid histiocytes with mixed inflammatory cell infiltrate and little necrosis. Innumerable acid-fast intracellular organisms can be demonstrated, but granulomas and multinucleated giant cells are absent (13-14). Imaging studies usually show an enhancing, dural-based mass that mimics meningioma or neurosarcoidosis. Once uncommon, their prevalence is rising as the number of immunocompromised patients increases worldwide. The most common are Coccidioides immitis, Aspergillus fumigatus, Cryptococcus neoformans, Histoplasma capsulatum, Candida albicans, and Blastomyces dermatitidis. Infection, Inflammation, and Demyelinating Diseases 386 Members of the Zygomycetes class (especially the Mucor genus) can also become pathogenic. Candidiasis, mucormycosis, and cryptococcal infections are usually opportunistic infections. They occur in patients with predisposing factors such as diabetes, hematologic malignancies, and immunosuppression. Coccidioidomycosis and aspergillosis affect both immunocompetent (often elderly) and immunocompromised patients. Coccidioidomycosis occurs in areas with low rainfall and high summer temperatures. In immunocompetent patients, fungi such as Blastomycosis and Histoplasma are usually confined to the lungs, where they cause focal granulomatous disease. Fungal sinonasal infections may invade the skull base and cavernous sinus directly. Pathology (13-17B) Axial section of cerebral hemisphere in the same case shows a hemorrhagic subcortical infarct. The meninges are the most common site, followed by the brain parenchyma and spinal cord. Fungal abscesses are encapsulated lesions with a soft tan or thick mucoid-appearing center, an irregular reddish margin, and surrounding edema. Disseminated disease is less common and causes a fungal cerebritis with diffusely swollen brain. Hemorrhagic infarcts, typically in the basal ganglia or at the gray-white matter junction, are common with angioinvasive fungi (13-17). On rare occasions, fungal infections can produce dura-based masses that closely resemble meningioma. Aspergillus has branching septated hyphae, whereas Tuberculosis and Fungal, Parasitic, and Other Infections Mucor has broad nonseptated hyphae. Fungal abscesses exhibit central coagulative necrosis with moderate amounts of acute (polymorphonuclear leukocytic) or chronic (lymphohistiocytic) inflammation mixed with variable numbers of fungal organisms. Abscesses are surrounded by a rim of granulation tissue, perivascular hemorrhage, and thrombosed vessels. Fungal granulomas are less common and are characterized by the presence of multinucleated giant cells.

If the middle fossa retractor is to be used hiv infection nejm discount starlix 120 mg online, it is especially important to ensure that the vertical bony cuts parallel each other to permit retention of the retractor antiviral movie youtube generic starlix 120 mg with visa. Care must be taken anti viral herb buy 120 mg starlix mastercard, regardless of the instruments used antiviral medication shingles cheap 120mg starlix with amex, to keep the underlying dura intact for maintaining an extradural plane of dissection hiv infection symptoms how soon discount starlix 120 mg on-line. In removing the bone flap, blunt dissection should be used to ensure that the dura is elevated off of the inner bony cortex (and thus does not tear). The bone flap should be set aside in a marked container for replacement during closure. Dural elevation and identification of dehiscence of the superior canal the dura underlying the temporal lobe is then elevated off the floor of the middle cranial fossa. Instruments should be directed in a sweeping motion from posterior to anterior to avoid subluxing a dehiscent facial nerve at the geniculate ganglion. Venous oozing is commonly encountered during dural elevation anteriorly and can readily be controlled using hemostatic agents (such as Surgifoam or Surgicel packing). Bipolar electrocautery can be used on the dura of the elevated temporal lobe to render it taut and thus help to lessen the need for manual retraction. A useful instrument to employ during exposure of the dehiscence is a small Brackmann-tipped suction irrigator; the continuous irrigation is useful for sweeping blood out of the field and keeping the field moist, while the small suction ports make it less likely that perilymph will be suctioned or inadvertent damage done to the endolymphatic membrane. Plugging dehiscence of the superior canal Once the dehiscence has been adequately exposed, the canal is plugged. Placement of a middle fossa retractor can be used for exposure during plugging, but that is often unnecessary. Rather, the side of the suction irrigator can be broadly applied to the temporal lobe dura to provide retraction during plugging. In A, a middle fossa retractor is in position (asterisk), elevating the temporal lobe dura for visualization of the left semicircular canal dehiscence (arrow). Also note the thin bone of the tegmen mastoideum overlying mastoid air cells (arrowheads) and contrast that bone with the dense labyrinthine bone of the arcuate eminence surrounding the site of superior semicircular canal dehiscence (best shown in panel B. Bone wax is placed onto the area of dehiscence, B, and a neurosurgical patty is used, C, to put inferior pressure on the wax such that it occludes the dehiscence, D. Pressure is directed inferiorly (toward the floor of the middle fossa and into the dehiscence) while the neurosurgical patty is removed to leave the bone wax in the site of dehiscence rather than allowing the wax to stick to the patty and be removed, risking damage to the endolymphatic membrane. Alternative materials that can be used for plugging include a mixture of bone wax and bone dust harvested during the craniotomy or a plug made up of fascia and bone chips. Care should be taken to make sure that both the ampullated and nonampullated ends of the canal are plugged. If additional skull base defects are identified, those should also be addressed (see Chapter 144). Failure to fully occlude the superior semicircular canal Irrespective of the material used to plug the dehiscence, the surgeon must ensure that both ends of the superior semicircular canal are plugged. If the surgeon fails to fully plug the canal, a third window will remain and symptoms may persist following surgery. Pain management: Oral or parenteral opiate analgesia is commonly required for several days following surgery. Physical activity: Patients should be expected to experience a lack of normal balance following surgery, since the plugged canal is rendered nonfunctional and central compensation takes time to develop. Patients should be assessed by physical therapy while they are in the hospital; outpatient vestibular rehabilitation should be recommended. Craniotomy not properly executed Missteps during the craniotomy can result in inadequate exposure. Failure to control this bleeding will cause blood to obscure the operative field, thus placing the dehiscence at risk for accidental manipulation. Standard treatments for unilateral sensorineural hearing loss can be considered if this complication were to occur (see Chapter 135). Transient sensorineural hearing loss is detected in some patients in the postoperative period but usually recovers when mild. If there is a significant change in hearing, steroid therapy should be considered. In cases where preoperative imaging is suggestive of a dehiscent geniculate ganglion, extra care should be taken to avoid this complication. Epidural hematoma Although uncommon, an epidural hematoma can appear following middle fossa craniotomy. Resurfacing of a dehiscent superior semicircular is associated with a higher rate of symptom recurrence than plugging of the affected canal. Minor, in reporting a series of patients (2005), found that four of 11 patients who underwent canal resurfacing without plugging developed recurrent symptoms within 3 to 6 months after surgery. On the other hand, of nine patient who underwent plugging, eight had complete resolution of symptoms and the ninth was "90% better. This imaging is necessary to demonstrate the presence and location of the bony defect and the surrounding anatomy of the temporal bone. The two schools of thought are capping (covering over the defect) and plugging (filling the defect with soft tissue, bone dust or bone wax). Initially a middle fossa approach was recommended to provide direct visualization of the dehiscence. Currently, if the amount of aeration in the antrum and tegmen are sufficient, a transmastoid approach can be executed. This usually entails covering of the bony defect with cartilage placed between the overlying dura and above the arcuate eminence. The canal can also be plugged isolating and unroofing its proximal and distal ends and occluding the membranous canal with soft tissue or bone wax. These repairs can be offered for signs and symptoms related to hearing loss and/or vertigo. People may experience low grade vestibulopathy problems related to motion intolerance. Partial or complete sensorineural hearing loss can occur due to manipulation of part of the inner ear. It is the disabling nature of the disorder that promotes patients toward having it repaired. Successful elimination of these life changing symptoms can be most rewarding to both the patient and surgeon. Sound- and/or pressureinduced vertigo due to bone dehiscence of the superior semicircular canal. The radiographic prevalence of geniculate ganglion dehiscence in normal and congenitally thin temporal bones. Transmastoid semicircular canal occlusion: a safe and highly effective treatment for benign paroxysmal positional vertigo and superior canal dehiscence. Superior canal dehiscence syndrome associated with the superior petrosal sinus in pediatric and adult patients. Near-dehiscence: clinical findings in patients with thin bone over the superior semicircular canal. In the past, hearing a patient indicate they hear themselves breathe, their eyes move or their heels hit a hard surface when walking were thought to carry a functional diagnosis. Failed stapes surgery for otosclerosis was deemed to be from an inner ear conductive disorder attributed to stiffness of the basilar membrane. It is now recognized that the third window effect provides a tangible explanation for this other source of conductive hearing loss. When the dura is elevated off the floor of the middle cranial fossa to expose a dehiscent superior semicircular canal, which of the following techniques should be used Identifying the middle meningeal artery and then dissecting in a posterior direction until the dehiscence is located 2. Complications of superior semicircular canal plugging include all of the following except a. All of the following structures are useful for identifying the location of a dehiscent superior semicircular canal except the a. Joseph Chang, Stephen Cass Acoustic neuroma, also known as vestibular schwannoma, is a benign neoplasm arising from the vestibular portion of the cochleovestibular nerve. This tumor can cause a variety of sequelae, most common among which are hearing loss, tinnitus, and dizziness/imbalance. The main goal in this endeavor is to prevent the tumor from growing to a large size, thus decreasing the likelihood of morbidity, while also minimizing the deleterious effects of treatment. Observation (watch and scan) has become more prevalent, adding another dimension to the decision making involved in treatment. On average these tumors grow slowly (2 mm per year), but the growth rate varies widely, with about 50% showing no growth during observation and others that grow an average of 2 to 4 mm per year (up to 18 mm). Moreover, the growth rate is nonlinear over time, since some growing tumors can stop growing while other tumors that showed no growth for years may start growing again. The advent of radiosurgery for the treatment of acoustic neuromas more than 40 years ago has significantly changed the contemporary management of acoustic neuroma. To date more than 100,000 patients with acoustic neuroma have been treated with radiosurgery, and the rate of radiosurgery treatment is growing. Currently about 50% of acoustic neuromas are treated with surgery, and the remainder are split between observation and radiosurgery. In addition to primary treatment for tumors, radiation offers a noninvasive treatment of residual tumor after microsurgery. Both types use precise stereotactic localization of the lesion as well as conformal treatment plans that focus the radiation beam on the target tissue. These use advanced robotic technology, multileaf collimators, and radiographic verification of positioning, all of which are highly accurate and flexible. This article discusses in further detail the management of acoustic neuroma with stereotactic radiosurgery. The management considerations are based on the limited data available at the time of writing. Patient selection is complex owing to the lack of reliable information on long-term tumor control rates after radiotherapy. The planning of tumor treatment must produce a highly conformal radiation field comprising the volume of the tumor and minimizing radiation to areas that are sensitive to radiation damage, including the cochlea and brainstem. The patient may have imbalance, a floating sensation, and vertigo; all of these may be affected by treatment. These may indicate a possible facial nerve schwannoma or a vascular tumor involving the facial nerve. Chronic serious medical conditions including coronary artery disease, chronic lung disease, chronic anticoagulation, or other conditions that may make the patient a poor surgical candidate Physical Examination 1. Videonystagmogram-This test may be performed if there are concerns regarding the status of contralateral vestibular function or the presence of other vestibular disorders. Patients who are medically unfit for surgery Patients who are fit for surgery but choose stereotactic radiation Tumors that have recurred after prior surgery Some tumors that have recurred after prior stereotactic radiation have been retreated with stereotactic radiation. Many centers may consider tumors with an axial dimension larger than 3 cm as too large for radiation, but there are reports of a few centers treating such large tumors. The presence of significant symptomatic brainstem compression usually requires surgical decompression with various degrees of tumor removal. Patients in their thirties or younger will have to consider the issue of very long term tumor control with radiotherapy and long-term radiation-induced complications. This technique is characterized by high-resolution targeting and registration of the lesion and very stable head/target positioning (1-mm accuracy). The structures that should receive as little radiation as possible include the following: a. During treatment the head is stabilized by the mask and radiographs are taken after each table and gantry movement to adjust for any movement of the head within the mask system. The Gamma Knife system is the most accurate, and is preferred when the greatest accuracy is required. For most other lesions, there is no practical difference between these approaches. The imaging data are imported into the targeting system for use in treatment planning. The Gamma Knife uses decaying Cobalt 60, which releases gamma radiation with an average energy of 1. The energy of the radiation affects the relationship of dose versus depth of tissue penetration. These differences are taken into account by the treatment planning software associated with each type of device. Conceptually, a device providing targeted treatment directs radiation from an external source at various angles to focus the dose on a central target. The lower the isodose line used, the greater the decline in dosage at the margin but also the greater the difference between the minimum and maximum doses to the tumor. For example, when treatment is directed to the 50% isodose line, the maximum dose will be double the marginal dose, creating a "hot spot" at the center of the tumor. An irregularly shaped isodose field can be created that conforms to the shape of the tumor to be treated. Perioperative Antibiotic Prophylaxis · None Monitoring · Video and audio systems to communicate with patient. The importance of differences in dose heterogeneity and isodose reference is not known. In the past, marginal doses of 25 to 50 Gy were used and resulted in significant rates of facial nerve dysfunction, trigeminal nerve dysfunction, edema of the brainstem, and hydrocephalus. These side effects have been reduced to very low levels with the currently used low doses. There is still a radiation dose field outside the prescription isodose volume that extends to the radiation source. The radiation dose to structures such as the inner ear and brainstem should be minimized in designing the prescription isodose volume and is termed blocking the area.

Relevant Anatomy Bony ridges and dural folds divide the intracranial cavity into three compartments: two supratentorial hemicrania (the right and left halves) and the posterior fossa (3-1) hiv infection condom starlix 120 mg purchase fast delivery. The dura mater consists of two layers antiviral zovirax purchase 120mg starlix with amex, an outer (periosteal) and an inner (meningeal) layer hiv infection rate malaysia purchase starlix 120mg online. The periosteal layer is tightly applied to the inner surface of the calvaria hiv infection how early symptoms discount starlix 120 mg free shipping, especially at suture lines antiviral honey order starlix 120 mg on-line. The meningeal layer folds inward to form two important fibrocollagenous sheets, the falx cerebri and tentorium cerebelli. The falx cerebri separates the right and left hemispheres from each other, whereas the tentorium cerebelli separates the supratentorial from the infratentorial compartment. It is shorter in front, where it is attached to the crista galli, and gradually deepens as it extends posteriorly. The concave inferior "free" margin of the falx contains the inferior sagittal sinus. As it courses posteriorly, the inferior margin of the falx forms a large open space above the corpus callosum and cingulate gyrus. This open space allows potential displacement of brain and blood vessels from one side toward the other. The opening is largest in the front and becomes progressively smaller, ending where the falx joins the tentorium cerebelli at its apex. The tentorium cerebelli is a tent-shaped dural sheet that extends inferolaterally from its confluence with the falx, where their two merging dural folds contain the straight sinus. The tentorium is attached laterally to the petrous ridges, anteroinferiorly to the dorsum sellae, and posteriorly to the occipital bone. It has two concave medial edges that contain a large U-shaped opening called the tentorial incisura (3-2). Displacement of brain structures and accompanying blood vessels from the supratentorial compartment or posterior fossa can occur in either direction-up or down-through the tentorial incisura. Parenchyma, cranial nerves, and/or blood vessels can become compressed against the adjacent unyielding bone and dura. Secondary ischemic changes, frank brain infarcts, cranial neuropathies, and focal neurologic deficits may develop. If treatment is unavailable or unsuccessful, severe neurologic damage or even death is the result of what becomes, in essence, a brain "compartment syndrome. Herniation occurs as the affected hemisphere pushes across the midline under the inferior "free" margin of the falx, extending into the contralateral hemicranium (3-3) (3-5). The ipsilateral ventricle appears compressed and displaced across the midline, while the contralateral ventricle (3-3) Autopsy shows subfalcine herniation. Left lateral ventricle is compressed, shifted across midline, as is cingulate gyrus. Right uncus and hippocampus are displaced medially and demonstrate "grooving" caused by impaction against tentorial incisura. The midbrain is compressed against the contralateral edge of the tentorial incisura. The uncus and hippocampus of both temporal lobes are herniated medially and inferiorly into the tentorial incisura. The cingulate gyrus and accompanying anterior cerebral arteries herniate under the falx (3-6). As the mass effect increases, the lateral ventricles become progressively more displaced across the midline. This displacement initially just deforms, then kinks, and eventually occludes the foramen of Monro. Severe unilateral obstructive hydrocephalus reduces drainage of extracellular fluid into the deep subependymal veins. Although these displacements can occur in both directions (from top down or bottom up), descending herniations from supratentorial masses are far more common than ascending herniations. As the mass effect increases, the uncus of the temporal lobe is pushed medially and begins to encroach on the suprasellar cistern. The hippocampus soon follows and starts to efface the ipsilateral quadrigeminal cistern. With progressively increasing mass effect, both the uncus and hippocampus herniate inferiorly through the tentorial incisura (3-7). Trauma 70 "Complete" or "central" descending herniation occurs when the supratentorial mass effect becomes so severe that the hypothalamus and optic chiasm are flattened against the skull base, both temporal lobes are herniated, and the whole tentorial incisura is completely plugged with displaced tissue (3-9). All the basal cisterns are obliterated as the hypothalamus and optic chiasm are crushed against the sella turcica, and the suprasellar and quadrigeminal cisterns are completely effaced (3-9) (3-13B). It is also pushed inferiorly through the tentorial incisura, displacing the pons downward. The angle between the midbrain and pons is progressively reduced from nearly 90° to almost 0° (3-11) (313B). In terminal central herniation, the pons eventually pushes the cerebellar tonsils inferiorly through the foramen magnum (3-12) (3-14A). In severe cases, the temporal horn can even be displaced almost into the midline (3-13A). The uncus and hippocampus of the left temporal lobe are herniated medially over the edge of the tentorium. The temporal horn of the compressed left lateral ventricle is almost in the midline. Mass effect is so severe that the inferior falx is bowed and the tentorium displaced inward. As the herniating temporal lobe pushes the midbrain toward the opposite side of the incisura, the contralateral cerebral peduncle is forced against the hard, knife-like edge of the tentorium, forming a Kernohan notch (3-15). Pressure ischemia leads to an ipsilateral (not contralateral) hemiplegia, the "false localizing" sign. Perforating arteries that arise from the top of the basilar artery are compressed and buckled inferiorly, eventually occluding and causing a secondary hemorrhagic midbrain infarct known as a Duret hemorrhage (3-7A). Terminology and Etiology In tonsillar herniation, the cerebellar tonsils are displaced inferiorly and become impacted into the foramen magnum (3-18). The most common cause is an expanding posterior fossa mass pushing the tonsils downward into the foramen magnum. In the sagittal plane, the normally horizontal tonsillar folia become vertically oriented, and the inferior aspect of the tonsils becomes pointed. Tonsils more than 5 mm below the foramen magnum are generally abnormal, especially if they are peg-like or pointed (rather than rounded). Complications of tonsillar herniation include obstructive hydrocephalus and tonsillar necrosis. The superiorly herniating cerebellum first flattens and displaces, then effaces the quadrigeminal cistern and compresses the midbrain (3-20). The quadrigeminal cistern is first compressed and then obliterated by the upwardly herniating cerebellum (322). In severe cases, the dorsal midbrain may actually appear concave instead of convex (3-20). Eventually, the entire tentorial incisura becomes completely filled with soft tissue, and all normal anatomic landmarks disappear. Other Herniations the vast majority of cerebral herniations are subfalcine, descending/ascending transtentorial, and tonsillar herniations. Other less common herniation syndromes are transalar and transdural/transcranial herniations. Transdural/Transcranial Herniation this rare type of cerebral herniation, sometimes called a "brain fungus" by neurosurgeons, can be life-threatening. Traumatic transdural/transcranial herniations typically occur in infants or young children with a comminuted skull fracture that deforms inward with impact, lacerating the dura-arachnoid. These responses include diffuse brain swelling, excitotoxic responses elicited by glutamatergic pathway activation, perfusion alterations, and a variety of ischemic events including territorial infarcts. Whether this is caused by increased tissue fluid (cerebral edema), or elevated blood volume (cerebral hyperemia) secondary to vascular dysautoregulation is unclear. In some cases, the trigeminal system may mediate brain swelling associated with subdural bleeding, providing the link between small-volume, thin subdural bleeds and swelling of the underlying brain. Massive brain swelling with severe intracranial hypertension is among the most serious of all secondary traumatic lesions. Mortality approaches 50%, so early recognition and aggressive treatment of this complication are imperative. Clinical Issues Children, young adults, and individuals with repetitive concussive or subconcussive injuries are especially prone to developing posttraumatic brain swelling and are almost twice as likely as older adults to develop this complication. Although gross enlargement of one or both hemispheres occasionally develops rapidly after the initial event, delayed onset is more (3-26) Autopsy case shows transdural/transcranial herniation. Increased intracranial pressure caused brain extrusion through a large craniectomy defect. Because of severe intraoperative brain swelling, an emergency decompressive craniectomy had to be performed. During the early stages of brain swelling, gray-white matter differentiation appears relatively preserved. Although the ipsilateral ventricle may be slightly compressed, subfalcine displacement is generally minimal. As brain swelling progresses, the demarcation between the cortex and underlying white matter becomes indistinct and eventually disappears. The lateral ventricles appear smaller than normal, and the superficial sulci are no longer visible. They have a variety of causes, including direct vascular compression, systemic hypoperfusion, vascular injury, vasospasm, and venous congestion. The most common cause of posttraumatic cerebral ischemia is mechanical vascular compression secondary to a brain herniation syndrome. Pressure necrosis of the uncus and hippocampus can also occur as the herniated temporal lobes impact the free edge of the tentorial incisura (3-10). Extraaxial hematomas that exert significant focal mass effect on the underlying brain may cause reduced arterial perfusion and cortical ischemia. They may also compress the underlying cortical veins, causing venous ischemia (3-35). Global or generalized cerebral ischemia may result from hypoperfusion, hypoxia, membrane depolarization, or loss of cellular membrane integrity and ion homeostasis. Cellular energy failure may induce glutamate-mediated acute excitotoxic brain injury. Posttraumatic vasospasm is seen as vascular irregularities without a clear dissection flap or intramural hematoma. The vertebral artery (usually between the skull base and C1) is the most commonly affected vessel. Anterior circulation dissections typically involve the supraclinoid internal carotid artery. Hyperintensity in the corpus callosum, right frontal lobe may represent excitotoxic injury. Since adoption of the Uniform Determination of Death Act, all court rulings in the United States have upheld the medical practice of death determination using neurologic criteria according to state law. Three clinical findings are necessary to confirm irreversible cessation of all functions of the entire brain, including the brainstem: (1) coma (with a known cause), (2) absence of brainstem reflexes, and (3) apnea. Complex spontaneous motor movements and false-positive ventilator triggering may occur in patients who are brain dead, so expert assessment is crucial. The superficial sulci, sylvian fissures, and basilar cisterns of both hemispheres are completely effaced (3-40). The normal attenuation relationship between gray and white matter is inverted, with gray matter becoming iso- or even hypodense relative to the adjacent white matter (the "reversal" sign). In striking contrast to the hypodense hemispheres, density of the cerebellum appears relatively normal (the "white cerebellum" sign). Density of the deep gray nuclei and brainstem may be initially maintained; however, all supratentorial structures eventually assume a featureless, uniform hypodensity. The hemispheres appear swollen and hypointense, with indistinct gray-white matter differentiation. Orbital Doppler shows absence or reversal of end-diastolic flow in central retinal arteries along with markedly increased arterial resistive indices. Tc-99m scintigraphy shows scalp uptake but absent brain activity ("light bulb" sign). Vascular lesions, such as arterial dissection and vasospasm, may also delay or even prevent opacification of intracranial vessels. End-stage brain swelling from severe trauma or profound hypoxic encephalopathy. Focal areas of encephalomalacia are most commonly found in areas with a high incidence of cortical contusions, i. These changes result in generalized atrophy and associated neurocognitive impairment. Posttraumatic Demyelination White matter tracts are particularly vulnerable to damage from impactacceleration/deceleration forces. Wallerian degeneration may occur as the axonal response to disconnection from initial mechanical forces and secondary insults. In some cases, subacute demyelination causes striking restricted diffusion of the subcortical and deep white matter (3-46). Progressive cognitive deterioration, recent memory loss, and mood and behavioral disorders such as paranoia, panic attacks, and major depression are common. Increased prevalence of a cavum septi pellucidi was present in those boxers with atrophy. Age-inappropriate volume loss and nonspecific white matter lesions are seen in 15% of cases (3-47A). Between 15-40% of former professional boxers have symptoms of chronic brain injury.

Multiple lesions including mixed intra- and extradural collections are seen in 15-20% of cases symptoms of hiv infection in one week 120 mg starlix buy with amex. Loculated and/or multiple unilateral collections are more common than separate bilateral empyemas antiviral film purchase starlix 120mg free shipping. The most common gross appearance of an empyema is an encapsulated antiviral yonkis order 120 mg starlix, thick natural antiviral herbs generic starlix 120 mg without prescription, yellowish hiv symptoms of infection buy starlix 120 mg online, purulent collection lying between the dura and the arachnoid. Early empyemas may be unencapsulated collections of cloudy, more fluid-like material. Microscopic features are those of nonspecific inflammatory infiltrate with varying amounts of granulation tissue. Clinical Issues (12-42) Purulent frontal sinusitis with extension into epidural space causes epidural empyema and frontal lobe cerebritis. An adolescent boy with significant headache and fever should elicit a high index of suspicion for sinusitis complications and prompt immediate imaging evaluation. The most common clinical presentation is headache, followed by fever and altered sensorium. The interval between initial infection (usually sinusitis) and onset of the empyema is typically 1-3 weeks. Once established, untreated empyemas can spread quite rapidly, extending from the extraaxial spaces into the subjacent brain. Besides cerebritis and abscess formation, the other major complication of empyema is cortical vein thrombosis with venous ischemia. Surgical drainage and rapid initiation of empiric intravenous antibiotic therapy (initially vancomycin and a third-generation cephalosporin) has been shown to reduce mortality. The extracerebral space is widened, and the underlying sulci are compressed by Congenital, Acquired Pyogenic, and Acquired Viral Infections the collection. The inwardly displaced dura can sometimes be identified as a thin hypointense line between the epidural collection and the underlying brain (12-43). Hyperintensity in the underlying brain parenchyma may be caused by cerebritis or ischemia (either venous or arterial). Empyemas show variable enhancement depending on the amount of granulomatous tissue and inflammation present (12-24). The encapsulating membranes, especially on the outer margin, enhance moderately strongly (12-43B) (12-44B) (12-45C). Congenital, Acquired Pyogenic, and Acquired Viral Infections 363 (12-47A) A 66y man developed headaches and frontal scalp swelling several weeks after resection of an anterior fossa meningioma. Note thin film of intradural fluid between layers of periosteal and meningeal dura. The virus initially gains entry into cells in the nasopharyngeal mucosa, invades sensory lingual branches of the trigeminal nerve, then passes in retrograde fashion into the trigeminal ganglion. It establishes a lifelong latent infection within sensory neurons of the trigeminal ganglion, where it can remain dormant indefinitely. Pathology (12-50B) Axial section in the same case shows petechial hemorrhages in insular cortex of both temporal lobes. The anterior and medial temporal lobes, insular cortex, subfrontal area, and cingulate gyri are most frequently affected (12-50A). Extratemporal, extralimbic Congenital, Acquired Pyogenic, and Acquired Viral Infections involvement occurs but is more common in children compared with adults. Massive tissue necrosis accompanied by numerous petechial hemorrhages and severe edema is typical. Inflammation and tissue destruction are predominantly cortical but may extend into the subcortical white matter. Perivascular lymphocytic cuffing with diffuse neutrophil infiltration into the necrotic parenchyma is typical. It follows a bimodal age distribution, with one-third of all cases occurring between the ages of 6 months and 3 years and one-half seen in patients older than 50. A viral prodrome followed by fever, headache, seizures, behavioral changes, and altered mental status is typical. Nearly two-thirds of survivors have significant neurologic deficits despite antiviral therapy. Hypodensity with mild mass effect in one or both temporal lobes and the insula may be present (12-51A). Infection, Inflammation, and Demyelinating Diseases 366 demonstrate cortical/subcortical hyperintensity with relative sparing of the underlying white matter. Enhancement varies from none (early) to intense gyriform enhancement several days later (12-52D). Extraaxial fungal infections are characterized predominantly by spindle cell proliferations. Aspergillosis accounts for 20-30% of fungal brain abscesses and is the most common cerebral complication following bone marrow transplantation. Immunocompetent patients have a bimodal age distribution with fungal infections disproportionately represented in children and older individuals. Imaging early in the course of a rapidly progressive infection in an immunocompromised patient may show diffuse cerebral edema more characteristic of encephalitis than fungal abscess. Patients with coccidioidal meningitis may demonstrate thickened, mildly hyperdense basal meninges. Multifocal parenchymal hemorrhages are common in patients with angioinvasive fungal species (13-19) (13-27). Multiple punctate or ringenhancing parenchymal lesions are typical findings of parenchymal mycetomas (13-20) (13-21). Mycetoma in the paranasal sinuses is usually seen as a single opacified hyperdense sinus that contains fine round to linear calcifications. Fungal sinusitis occasionally becomes invasive, crossing the mucosa to involve blood vessels, bone, orbit, cavernous sinuses, and intracranial cavities. Focal or widespread bone erosion with adjacent soft tissue infiltration can mimic neoplasm. Thick enhancing exudate entirely fills suprasellar and prepontine cisterns and cisterna magna and extends inferiorly around the cervical spinal cord. Focal lesions (mycetomas) show high signal foci that typically have a peripheral hypointense rim, surrounded by vasogenic edema. T2* scans may show "blooming" foci caused by hemorrhages or calcification (13-26). Angioinvasive fungi may erode the skull base, cause plaque-like dural thickening, and occlude one or both carotid arteries (13-29) (13-30). Parenchymal lesions show punctate, ring-like, or irregular enhancement (13-23B) (13-25) (13-26). A lactate peak is seen in 90% of cases, whereas lipid and amino acids are identified in approximately 50%. Gross hemorrhage is more common with fungal than either pyogenic or tubercular abscesses. Fungal abscesses have more irregularly shaped walls and internal nonenhancing projections. Infection, Inflammation, and Demyelinating Diseases 390 (13-25) (Top) Autopsy case demonstrates multiple solid, necrotic Nocardia abscesses in the cortex, gray-white matter junctions. When they infest the brain, parasites can cause very bizarre-looking masses that can mimic neoplasm. A "cysticercus" cyst in the brain is actually the secondary larval form of the parasite. In the larval form, the scolex is invaginated into one end of the cyst, which is called the "bladder. The eggs hatch and release their larvae that then disseminate via the bloodstream to virtually any organ in the body. The lesion invades the left orbit and extends posteriorly, obstructing the sphenoid sinus. Infection, Inflammation, and Demyelinating Diseases 392 (13-29) Close-up view shows autopsied cavernous sinus with invasive fungal sinusitis occluding the left cavernous internal carotid artery. Invasive sinonasal mucormycosis in a diabetic patient is a potentially lethal lesion. This patient died from a massive left middle cerebral artery stroke shortly after the scan. In the vesicular stage, viable larvae (the cysticerci) appear as translucent, thin-walled, fluid-filled cysts with an eccentrically located, whitish, invaginated scolex (13-32) (13-33). A striking inflammatory response is incited and characterized by a collection of multinucleated giant cells, macrophages, and neutrophils. The granular nodular stage represents progressive involution with collapse and retraction of the cyst into a granulomatous nodule that will eventually calcify. Edema persists, but pericystic gliosis is the most common pathologic finding at this stage. In the nodular calcified stage, the entire lesion becomes a fibrocalcified nodule (13-34). Convexity cysts have scolex and surrounding inflammation, which, around the largest cyst, "seals" the sulcus, makes it appear parenchymal. Signs and symptoms depend on number and location of larvae, developmental stage, infection duration, and presence or absence of host immune response. Seizures/epilepsy are the most common symptoms (80%) and are a result of inflammation around degeneration cysts. The time to progress through all four stages varies from 1-9 years with a mean of 5 years. Oral albendazole with or without steroids, excision/drainage of parenchymal lesions, and endoscopic resection of intraventricular lesions are treatment options. Several foci of perilesional edema are apparent around lesions in the colloidal vesicular stage, whereas minimal residual edema surrounds lesions in the granular nodular stage. Note hydrocephalus, meningeal reaction with mild/moderate rim enhancement around the "bunch of grapes" cysts. Moderate to marked surrounding edema is present (1338B) and may even progress to a diffuse encephalitis. Enhancement of the cyst wall is typically intense, ring-like, and often slightly "shaggy" (13-38D) (13-40). Restricted diffusion in the scolex and viscous degenerating cyst can be present (13-39). The cyst wall appears thickened and retracted, and the perilesional edema diminishes substantially, eventually disappearing. Arachnoiditis with fibrosis and scarring demonstrates rim enhancement around the cysts and along the brain surfaces. Most infarcts involve small perforating vessels although large territorial infarcts have been reported. The fourth ventricle is the most common site (5055%) (13-37) followed by the third ventricle (25-30%), lateral ventricle (10-12%), and aqueduct (8-10%). Infection, Inflammation, and Demyelinating Diseases 398 (13-42A) T1 C+ scan in a 20y man with alveolar echinococcosis demonstrates cauliflower-like clusters of multiple small, irregular, ring-enhancing cysts. Humans-most often children-become accidental intermediate hosts by ingesting eggs in soil contaminated by excrement from a definitive host. Tuberculosis and Fungal, Parasitic, and Other Infections 399 (13-43A) Autopsy case shows brain after the removal of a huge unilocular hydatid cyst. There is no surrounding edema, and the mass effect relative to the size of the cyst is minimal. Sometimes a detached germinal membrane and hydatid "sand" can be seen in the dependent portion of the cyst (13-46). Irregular peripheral or ring-like, heterogeneous, nodular, and cauliflower-like patterns have been reported (13-42). Differential Diagnosis the differential diagnosis of a supratentorial intraaxial cystic mass is extensive and includes cystic neoplasms, abscess, parasitic cysts, and neuroglial cysts. Porencephalic cysts are literally "holes in the brain" adjacent to-and usually connected with-an enlarged ventricle. Amebiasis Terminology and Etiology Amebae are free-living organisms that are distributed worldwide. Species of the Acanthamoeba (Ac) genus are found in soil and dust, fresh or brackish water, and a variety of other locations ranging from hot tubs and hydrotherapy pools to air conditioning units, contact lens solutions, and dental irrigation units. Amebic abscess occurs but is relatively uncommon in Western and industrialized countries. Numerous trophozoites are present, but no cysts are seen because of disease acuity. Healthy children and immunocompetent young adults swimming in warm fresh water during the summer are the typical patients, presenting with fever, headache, and altered mental status. Presentation ranges from headache and chronic low-grade fever to (13-47C) Histology shows meningitis, hemorrhage/inflammatory cells in Virchow-Robin spaces. Infection, Inflammation, and Demyelinating Diseases 402 (13-51) Sporozoites inoculated into blood infect the liver cells. Merozoites develop into trophozoites or gametocytes, which are then ingested by uninfected mosquitoes. Symptoms are nonspecific and include headache, altered mental status, and meningeal symptoms. Amebic abscesses and meningoencephalitis can mimic disease caused by other pyogenic, parasitic, and granulomatous infections. The life cycle of a malaria parasite involves the female Anopheles mosquito and a human host. Merozoites can develop into trophozoites, which undergo asexual reproduction in the blood, or into gametocytes, which reproduce sexually in deep tissue capillaries. Gametocytes are ingested by mosquitoes, and the cycle is repeated over and over again (13-51).

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