Robert A. Egan

MRI findings in Susac’s syndrome

Background: Susac syndrome (SS) is a self-limited syndrome, presumably autoimmune, consisting of a clinical triad of encephalopathy, branch retinal artery occlusions, and hearing loss. All three elements of the triad may not be present or recognized, and MR imaging is often necessary to establish the diagnosis. Objective: To determine the spectrum of abnormalities on MRI in SS. Methods: The authors reviewed the MR images of 27 previously unreported patients with the clinical SS triad, and 51 patients from published articles in which the MR images were depicted or reported. Results: All 27 patients had multifocal supratentorial white matter lesions including the corpus callosum. The deep gray nuclei (basal ganglia and thalamus) were involved in 19 (70%). Nineteen (70%) also had parenchymal enhancement and 9 (33%) had leptomeningeal enhancement. Of the 51 cases from the literature, at least 32 had callosal lesions. The authors could not determine the presence of callosal lesions in 18 of these patients, and only one was reported to have a normal MRI at the onset of encephalopathy. Conclusions: The MR scans in SS show a rather distinctive pattern of supratentorial white matter lesions that always involve the corpus callosum. There is often deep gray matter, posterior fossa involvement, and frequent parenchymal with occasional leptomeningeal enhancement. The central callosal lesions differ from those in demyelinating disease, and should support the diagnosis of SS in patients with at least two of the three features of the clinical triad.

Sildenafil-associated nonarteritic anterior ischemic optic neuropathy

PURPOSE To describe the clinical features of five patients who developed nonarteritic anterior ischemic optic neuropathy (NAION) after ingestion of sildenafil citrate (Viagra; Pfizer Pharmaceuticals, New York, NY). DESIGN Retrospective observational case series. PARTICIPANTS Five patients with NAION who reported the use of sildenafil citrate before the onset of ocular symptoms. MAIN OUTCOME MEASURES The symptoms presented, history, ophthalmic examination, and visual field examination of each patient. RESULTS Nonarteritic anterior ischemic optic neuropathy developed in one eye within minutes to hours after ingestion of sildenafil. Four of the five patients had no vascular risk factors for ischemic optic neuropathy. The patients all developed unilateral blurry vision, altitudinal visual field defects, and optic disc edema. Each of the patients was noted to have a small cup-to-disc ratio in the unaffected optic nerve. CONCLUSIONS Sildenafil citrate may be associated with NAION. A small cup-to-disc ratio may be a risk factor for development of NAION in association with the use of sildenafil.

Susac's syndrome: 1975–2005 microangiopathy/autoimmune endotheliopathy

Susacs syndrome (SS) consists of the clinical triad of encephalopathy, branch retinal artery occlusions (BRAO) and hearing loss. It is due to a microangiopathy affecting the precapillary arterioles of the brain, retina, and inner ear (cochlea and semicircular canals). Women are more commonly affected than men (3:1); the age of onset ranges from 9 to 58 years; but young women between the ages of 20 and 40 are most vulnerable. The encephalopathy is almost always accompanied by headache which may be the presenting feature. Multifocal neurological signs and symptoms, psychiatric disturbances, cognitive changes, memory loss, and confusion may rapidly progress to dementia. The MRI shows a distinctive white matter disturbance that always affects the corpus callosum. The central callosal fibers are particularly vulnerable and central callosal holes develop as the active lesions resolve. Linear defects (spokes) and rather large round lesions (snowballs) sometime dominate the MRI findings, which include cortical, deep gray (70%) and leptomeningeal involvement (33%). Frequently, the lesions enhance and may be evident on diffusion weighted imaging (DWI). The BRAO are best evaluated with fluorescein angiography, which may show the pathognomonic multifocal fluorescence. Gass plaques are frequently present and reflect endothelial damage. Brain biopsy shows microinfarction to be the basic pathology, but more recent pathological studies have shown endothelial changes that are typical for an antiendothelial cell injury syndrome. Elevated levels of Factor VIII and von Willebrand Factor Antigen reflect the endothelial perturbation. Despite extensive evaluations, a procoagulant state has never been demonstrated. SS is an autoimmune endotheliopathy that requires treatment with immunosuppressants: steroids, cyclophosphamide, and intravenous immunoglobulin, usually in combination. Aspirin is a useful adjunct.

Visual field deficits in conventional anterior temporal lobectomy versus amygdalohippocampectomy

Objective: To evaluate and identify the incidence of visual field defects (VFD) after anterior temporal lobectomy (ATL) versus amygdalohippocampectomy (AH). VFD occur frequently after ATL and are usually superotemporal quadrantanopias. Little is known about the incidence of VFD after AH and this surgical method offers the possibility of a seizure-free survival without visual loss. Methods: Patients with similar characteristics were examined. All patients had intractable seizures and mesial temporal sclerosis, small tumors localized to only the uncus, amygdala, or hippocampus, or no known pathology. Postoperative kinetic field testing using the I4e isopter on a Goldmann perimeter was performed 30 days or more after surgery. Results: Of 29 patients examined, 14 underwent AH and 15 had ATL. Four of 14 AH patients (28%) had a VFD at 10 degrees from center and 11/14 (78%) had VFD at 40 degrees. One of 15 ATL patients (7%) had a VFD at 10 degrees from center and 11/15 (73%) had VFD at 40 degrees. There was no significant difference between surgery types. Conclusions: AH in this study was associated with a significant number of VFD. No significant difference was found between the frequency of VFD produced from AH and ATL. The mechanism of injury is due to direct trauma to the optic radiations while accessing the mesial temporal structures. Because all patients in the study were asymptomatic for VFD, it remains to be determined whether these VFD are clinically significant.

Retinal arterial wall plaques in Susac syndrome

PURPOSE To demonstrate retinal arterial wall plaques (RAWPs) in patients with Susac syndrome, a disorder that consists of the triad of branch retinal artery occlusion, encephalopathy, and hearing loss. The clinician may misinterpret these RAWPs as emboli. DESIGN Observational case series. METHODS Four patients (one man and three women, aged 21-38 years) were examined and followed. RESULTS Four patients with Susac syndrome had RAWPs in association with branch retinal artery occlusions. They were present in six of eight eyes. The plaques were yellow to yellow-white and located usually away from retinal bifurcations. Retinal arterial wall plaques occur at the midarteriolar segments, whereas Hollenhorst plaques occur at vascular bifurcations. Four of six eyes had resolution of the plaques. CONCLUSIONS Retinal arterial wall plaques may occur with branch retinal artery occlusions in Susac syndrome. This finding should help the clinician who is struggling to make a diagnosis in a patient with an enigmatic encephalopathy and/or hearing loss. These plaques may resolve over time.

Frequency and amplitude of elevation of cerebrospinal fluid resting pressure by the Valsalva maneuver.

BACKGROUND Patients are referred to ophthalmologists to evaluate for papilledema when they are found to have elevated cerebrospinal fluid (CSF) pressure. However, some of these patients have no clinical history consistent with intracranial hyper-tension. We aimed to determine how often and how high patients with normal opening pressure could artificially elevate their CSF pressure to a pseudo-pathologic level by performing a Valsalva maneuver. METHODS We measured CSF pressure at rest and after a Valsalva maneuver in 15 consecutive normotensive patients referred for CSF analysis to determine the frequency and amplitude of elevation of pressure. Manometry was performed in the standard lateral decubitus position with legs and knees extended and abdomen relaxed and then again during a Valsalva maneuver with hip flexion and bearing down against a closed glottis. RESULTS All 15 normotensive patients elevated their CSF pressure to levels greater than 25 cm water. One patient reached a maximum pressure of 47 cm water. INTERPRETATION Artifactual elevation of CSF pressure may therefore occur frequently. Caution is advised before accepting a diagnosis of intracranial hypertension in those lacking this syndrome. These patients require repeat CSF pressure measurements to either verify or refute previous recordings.

Prevalence of organic Neuro-ophthalmologic disease in patients with functional visual loss

PURPOSE To determine the concurrence of various patterns of functional visual loss (FVL) and organic disease. DESIGN A retrospective case series in a university neuro-ophthalmology practice. METHODS A retrospective case series in which we reviewed the clinical histories and neuro-ophthalmologic examinations of 133 consecutive patients diagnosed with FVL between July 1999 and August 2001. Functional visual loss was defined as an apparent afferent or efferent dysfunction that was unassociated with or far out of proportion with an identifiable lesion of the visual pathways. RESULTS A total of 133 patients were identified. Nineteen were pediatric, and 76 were female. Fifty-six had concurrent head or eye pain. Nineteen had a recent history of trauma, and 17 had a recent surgical procedure. The most common pattern of FVL was a normal visual field in the presence of reduced visual acuity. Seventy-one patients (53%) with FVL presented with abnormal neuro-ophthalmologic examinations. Thirteen patients had central scotomata, and all had concurrent retinal or optic nerve pathology. Only 18 patients had a known disability claim pending. CONCLUSION Although FVL was found in patients with no pathology, it was more common to find objective abnormalities on examination. This concurrence rate underscores the clinical necessity for following patients closely despite the diagnosis of FVL. No pattern of visual field constriction was routinely predictive of ophthalmologic or neurologic pathology except the presence of a central scotoma. The presence of a central scotoma in a nonorganic visual field should alert the practitioner to search for organic pathology.

Doxycycline and intracranial hypertension

The authors report seven patients from six neuro-ophthalmology referral centers who developed pseudo-tumor cerebri during treatment with doxycycline. All four female patients and one of three male patients were obese. Vision was minimally affected in most patients, but two had substantial visual acuity or visual field loss at presentation. Discontinuation of doxycycline, with or without additional intracranial pressure-lowering agents, yielded improvement, but permanent visual acuity or visual field loss occurred in five patients.

Gass plaques and fluorescein leakage in Susac Syndrome

INTRODUCTION Susac Syndrome (SS) consists of the triad of encephalopathy, branch retinal artery occlusion, and hearing loss. It is an autoimmune endotheliopathy that primarily affects young women. Two funduscopic findings, Gass plaques (GP) and arteriolar wall hyperfluorescence (AWH), have recently been described and are not only useful in making the SS diagnosis but also point to the endothelium as the site of autoimmune injury. In this report we wish to raise awareness of GP and AWH with this disorder. METHODS Four selected SS cases are presented with fundus photographs revealing GP. Fluorescein angiographic photographs are shown describing AWH. RESULTS GP are shown in several cases. These GP are unique in that they are yellow, sometimes refractile, and located distant from retinal arteriolar bifurcations unlike Hollenhorst plaques which are orange and located at retinal arteriolar bifurcations. Fluorescein angiography displays AWH of the retinal arterioles of patients with SS distant from affected vessels which has not been demonstrated in other retinal vasculitides. CONCLUSION Small punctuate yellow GP are almost unique to this disorder and their characteristic location and color should assist in confirming the diagnosis. Fluorescein angiography should be performed in all patients with an unexplained encephalopathy to look for the characteristic AWH pattern that occurs in this illness.

Monocular blindness as a complication of trigeminal radiofrequency rhizotomy

PURPOSE To raise the awareness of the rare complication of monocular blindness resulting from radiofrequency rhizotomy for trigeminal neuralgia. METHODS Case series from tertiary referral centers. Patients were referred after complaint of loss of vision. RESULTS We report three patients who had trigeminal neuralgia and underwent treatment by radiofrequency rhizotomy. Each developed complete loss of vision in one eye immediately after the procedure. One patient died of an unrelated cause, and pathologic analysis revealed changes compatible with acute trauma to the right optic nerve. CONCLUSION Our third case confirms the hypothesis that traumatic optic neuropathy after trigeminal radiofrequency rhizotomy results from malpositioning of the rhizotomy needle through the inferior orbital fissure into the orbital apex rather than the foramen ovale.