Shlomo Dotan

Minocycline treatment and pseudotumor Cerebri syndrome

PURPOSE To demonstrate the association between minocycline treatment and development of the pseudotumor cerebri syndrome. METHODS A retrospective study was conducted of 12 patients from five neuro-ophthalmic referral centers who developed pseudotumor cerebri syndrome after being treated with standard doses of minocycline for refractory acne vulgaris. The main outcome measures included resolution of headaches, transient visual obscurations, diplopia, papilledema, and visual fields static thresholds after withdrawal of minocycline and treatment for increased intracranial pressure. RESULTS Nine (75%) of the 12 patients developed symptoms of the pseudotumor cerebri syndrome syndrome within 8 weeks of starting minocycline therapy; six were not obese. Two patients developed symptoms only after a year had elapsed because of commencement of treatment with minocycline. One patient was asymptomatic, and pseudotumor cerebri syndrome was diagnosed by finding papilledema on routine examination 1 year after minocycline was started. None of the patients developed recurrences for at least 1 year after the discontinuation of minocycline and treatment for increased intracranial pressure, but three (25%) of the 12 patients had substantial residual visual field loss. CONCLUSION Minocycline is a cause or precipitating factor in pseudotumor cerebri syndrome. Although most patients have prominent symptoms and are diagnosed promptly, others are asymptomatic and may have optic disk edema for a long period of time before diagnosis. Withdrawal of minocycline and treatment for increased intracranial pressure lead to resolution of the pseudotumor cerebri syndrome, but visual field loss may persist.

Normal and abnormal fMRI activation patterns in the visual cortex after recovery from optic neuritis.

Recovery to normal or near normal visual acuity after an optic neuritis episode is common, despite frequent persistence of conduction abnormalities, evident in prolonged visual evoked potential (VEP) latencies. Improvement of visual function is commonly attributed to peripheral nerve recovery. However, central reorganization processes may also be involved. To assess this, we compared the patterns of fMRI activation, elicited by stimulation of the affected and the normal eye, along the visual cortical hierarchy. Activation was assessed in 8 subjects, which recovered clinically from an episode of optic neuritis but still had prolonged VEP latencies. In all patients, reduced fMRI activation was seen in V1 during stimulation of the affected eye, compared to the normal eye. The fMRI signal difference decreased in magnitude with progression along the visual hierarchy, and in some regions within the lateral occipital complex even showed the opposite preference (for the affected eye). These results may indicate a built-in robustness of the object-related areas to disruption of the visual input. Alternatively, it could reflect an adaptive functional reorganization of the cortical response to an abnormal input.

Fe/S protein assembly gene IBA57 mutation causes hereditary spastic paraplegia

Objective: To present the clinical, molecular, and cell biological findings in a family with an autosomal recessive form of hereditary spastic paraplegia characterized by a combination of spastic paraplegia, optic atrophy, and peripheral neuropathy (SPOAN). Methods: We used a combination of whole-genome linkage analysis and exome sequencing to map the disease locus and to identify the responsible gene. To analyze the physiologic consequences of the disease, we used biochemical and cell biological methods. Results: Ten members of a highly consanguineous family manifested a childhood-onset SPOAN-like phenotype with slow progression into late adulthood. We mapped this disorder to a locus on chromosome 1q and identified a homozygous donor splice-site mutation in the IBA57 gene, previously implicated in 2 infants with lethal perinatal encephalomyopathy. This gene encodes the mitochondrial iron-sulfur (Fe/S) protein assembly factor IBA57. In addition to a severely decreased amount of normal IBA57 messenger RNA, a patients cells expressed an aberrantly spliced messenger RNA with a premature stop codon. Lymphoblasts contained 10-fold–lower levels of wild-type, but no signs of truncated IBA57 protein. The decrease in functional IBA57 resulted in reduced levels and activities of several mitochondrial [4Fe-4S] proteins, including complexes I and II, while mitochondrial [2Fe-2S] proteins remained normal. Conclusions: Our findings reinforce the suggested specific function of IBA57 in mitochondrial [4Fe-4S] protein maturation and provide additional evidence for its role in human disease. The less decreased IBA57 protein level in this family explains phenotypic differences compared with the previously described lethal encephalomyopathy with no functional IBA57.

Demyelination affects temporal aspects of perception: An optic neuritis study

Visual Evoked Potentials (VEPs) following optic neuritis (ON) remain chronically prolonged, although standard visual tests indicate full recovery. We hypothesized that dynamic visual processes, such as motion perception, may be more vulnerable to slowed conduction in the optic nerve, and consequently be better associated with projection rates.

Sustained motion perception deficit following optic neuritis Behavioral and cortical evidence

Objective: To assess the recovery process in patients after an acute optic neuritis (ON) attack, comparing static and dynamic visual functions. Methods: In this prospective controlled study, 21 patients with unilateral, first-ever ON were followed over the course of 1 year. Standard visual tests, visual evoked potentials, and optical coherence tomography were assessed repeatedly. In addition, we developed a novel set of motion perceptual tasks to test dynamic visual deficits. fMRI examinations were performed to study the neuronal correlates for the behavioral findings. Results: Four months after the acute phase, the affected eyes had returned to normal performance levels in the routine visual testing. However, motion perception remained impaired throughout the 12-month period. In agreement with the clinical findings, fMRI studies showed recovery in cortical activation during static object recognition, as opposed to sustained deficit in tasks that require motion perception. Conclusions: Sustained motion perception deficit following ON may explain the continued visual complaints of patients long after recovery of visual acuity. Cortical activation patterns suggest that if plastic processes in higher visual regions contribute to the recovery of vision, this may be limited to static visual functions. Alternatively, cortical activation may reflect the visual percept (intact for visual acuity and impaired for motion perception), rather than demonstrating plastic processes. We suggest that motion perception should be included in the routine ophthalmologic tests following ON.

Rathke’s Cleft Cyst Abscess

Pituitary abscesses are rare. Occasionally they will arise in pre-existing pituitary pathology. We report such an occurrence within a Rathke’s cleft cyst. On the basis of history and imaging, this was indistinguishable from more commonly encountered pituitary pathology.

Recurrent Abducens Nerve Palsy Caused by Dolichoectasia of the Cavernous Internal Carotid Artery

PURPOSE To describe a 59-year-old patient who had seven recurrent, self-limited episodes of isolated ipsilateral abducens nerve palsy in the previous 4 years. Each episode lasted between 2 and 5 weeks. METHODS Systemic examination and neuroimaging studies were performed. RESULT Repeated comprehensive examination failed to demonstrate any ocular or systemic condition apart from a lateral protrusion by dolichoectasia of the posterior portion of the cavernous left internal carotid artery, compressing the posterior left cavernous sinus. CONCLUSION Numerous self-limited episodes of sixth nerve palsy may be associated with structural abnormalities of the intracranial carotid vasculature.

Giant anterior clinoidal meningiomas: surgical technique and outcomes

OBJECT Surgery for giant anterior clinoidal meningiomas that invade vital neurovascular structures surrounding the anterior clinoid process is challenging. The authors present their skull base technique for the treatment of giant anterior clinoidal meningiomas, defined here as globular tumors with a maximum diameter of 5 cm or larger, centered around the anterior clinoid process, which is usually hyperostotic. METHODS Between 2000 and 2010, the authors performed 23 surgeries in 22 patients with giant anterior clinoidal meningiomas. They used a skull base approach with extradural unroofing of the optic canal, extradural clinoidectomy (Dolenc technique), transdural debulking of the tumor, early optic nerve decompression, and early identification and control of key neurovascular structures. RESULTS The mean age at surgery was 53.8 years. The mean tumor diameter was 59.2 mm (range 50-85 mm) with cavernous sinus involvement in 59.1% (13 of 22 patients). The tumor involved the prechiasmatic segment of the optic nerve in all patients, invaded the optic canal in 77.3% (17 of 22 patients), and caused visual impairment in 86.4% (19 of 22 patients). Total resection (Simpson Grade I or II) was achieved in 30.4% of surgeries (7 of 23); subtotal and partial resections were each achieved in 34.8% of surgeries (8 of 23). The main factor precluding total removal was cavernous sinus involvement. There were no deaths. The mean Glasgow Outcome Scale score was 4.8 (median 5) at a mean of 56 months of follow-up. Vision improved in 66.7% (12 of 18 patients) with consecutive neuroophthalmological examinations, was stable in 22.2% (4 of 18), and deteriorated in 11.1% (2 of 18). New deficits in cranial nerve III or IV remained after 8.7% of surgeries (2 of 23). CONCLUSIONS This modified surgical protocol has provided both a good extent of resection and a good neurological and visual outcome in patients with giant anterior clinoidal meningiomas.

Myelin-associated glycoprotein gene mutation causes Pelizaeus-Merzbacher disease-like disorder

Pelizaeus-Merzbacher disease is an X-linked hypomyelinating leukodystrophy caused by mutations or rearrangements in PLP1. It presents in infancy with nystagmus, jerky head movements, hypotonia and developmental delay evolving into spastic tetraplegia with optic atrophy and variable movement disorders. A clinically similar phenotype caused by recessive mutations in GJC2 is known as Pelizaeus-Merzbacher-like disease. Both genes encode proteins associated with myelin. We describe three siblings of a consanguineous family manifesting the typical infantile-onset Pelizaeus-Merzbacher disease-like phenotype slowly evolving into a form of complicated hereditary spastic paraplegia with mental retardation, dysarthria, optic atrophy and peripheral neuropathy in adulthood. Magnetic resonance imaging and spectroscopy were consistent with a demyelinating leukodystrophy. Using genetic linkage and exome sequencing, we identified a homozygous missense c.399C>G; p.S133R mutation in MAG. This gene, previously associated with hereditary spastic paraplegia, encodes myelin-associated glycoprotein, which is involved in myelin maintenance and glia-axon interaction. This mutation is predicted to destabilize the protein and affect its tertiary structure. Examination of the sural nerve biopsy sample obtained in childhood in the oldest sibling revealed complete absence of myelin-associated glycoprotein accompanied by ill-formed onion-bulb structures and a relatively thin myelin sheath of the affected axons. Immunofluorescence, cell surface labelling, biochemical analysis and mass spectrometry-based proteomics studies in a variety of cell types demonstrated a devastating effect of the mutation on post-translational processing, steady state expression and subcellular localization of myelin-associated glycoprotein. In contrast to the wild-type protein, the p.S133R mutant was retained in the endoplasmic reticulum and was subjected to endoplasmic reticulum-associated protein degradation by the proteasome. Our findings identify involvement of myelin-associated glycoprotein in this family with a disorder affecting the central and peripheral nervous system, and suggest that loss of the protein function is responsible for the unique clinical phenotype.

Parasellar Meningiomas in Pregnancy: Surgical Results and Visual Outcomes

BACKGROUND Rapid visual deterioration may occur as the result of the quick growth of parasellar meningiomas in the high-hormone/increased fluid retention milieu of pregnancy; however, surgery before delivery entails increased maternal-fetal risk. We present our experience in the management of parasellar meningiomas that compress the optic apparatus during pregnancy, with a focus on decisions regarding the timing of surgery. METHODS Serial visual examinations and other clinical data for 11 women presenting from 2002 to 2012 with visual deterioration during pregnancy or delivery as the result of parasellar meningiomas involving the optic apparatus were reviewed. Indications for surgery during pregnancy included severely compromised vision, rapid visual deterioration, and early-to-midstage pregnancy with the potential for significant tumor growth and visual decrease before delivery. All patients underwent surgery with the use of skull base techniques via pterional craniotomy. An advanced extradural-intradural (i.e., Dolenc) approach, with modifications, was used in seven. RESULTS All women achieved a Glasgow Outcome Score of 5 at discharge with no new neurologic deficits; all children are developing normally at a mean 4.5 years of age (range, 1-9.5 years). Surgery during pregnancy was recommended for six women: four operated at gestational weeks 20-23 had excellent postoperative visual recovery; two who delayed surgery until after delivery have permanent unilateral blindness. Among five others operated after delivery, four had good visual recovery and one has pronounced but correctable deficits. Three of five women diagnosed at gestational weeks 32-35 experienced spontaneous visual improvement after delivery, before surgery. CONCLUSIONS We recommend that surgery be offered to patients during pregnancy when a delay may result in severe permanent visual impairment.