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Biomedical subjects

Michael C Brodsky

Publications and source records attributed to Michael C Brodsky.

At least 19 recordsLinked to original sources
PubMed2006

Mutations in FRMD7, a newly identified member of the FERM family, cause X-linked idiopathic congenital nystagmus.

Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability.

Brain↗
PubMed2005

Visuo-vestibular eye movements: infantile strabismus in 3 dimensions.

Infantile strabismus is accompanied by latent nystagmus, primary inferior oblique muscle overaction, and dissociated vertical divergence. If we examine the evolutionary underpinnings of these ocular rotations, we can construct a unifying mechanism for the sensorimotor abnormalities that arise in humans with infantile strabismus. Latent nystagmus, primary inferior oblique muscle overaction, and dissociated vertical divergence correspond to visual balancing reflexes that are operative in lateral-eyed animals in yaw, pitch, and roll, respectively. In humans with infantile strabismus, these subcortical visual reflexes are reactivated by a physiologic imbalance in binocular visual input, which resets central vestibular tone in 3-dimensional space. These visual reflexes reveal the evolutionary role of the eyes as sensory balance organs that can directly modulate central vestibular tone. Latent nystagmus, primary oblique muscle overaction, and dissociated vertical divergence should be reclassified as visuo-vestibular eye movements.

Animals↗
PubMed2005

The reversed fixation test: a diagnostic test for dissociated horizontal deviation.

BACKGROUND: Dissociated horizontal deviation is one of several conditions that manifest unequal horizontal deviations depending on which of the 2 eyes is fixating. PURPOSE: To describe the reversed fixation test as an essential tool to establish the diagnosis of dissociated horizontal deviation. METHODS: Analysis of 4 case scenarios depicting the utility of the reversed fixation test. RESULTS: The reversed fixation test distinguishes dissociated horizontal deviation from an unequal exodeviation of the 2 eyes resulting from postoperative slippage or weakness of a horizontal rectus muscle. CONCLUSION: The reversed fixation test is necessary to establish the diagnosis of dissociated horizontal deviation.

Diagnostic Techniques, Ophthalmological↗
PubMed2004

Neurologic impairment 10 years after optic neuritis.

BACKGROUND: Participants enrolled in the Optic Neuritis Treatment Trial have been observed for more than a decade to assess the relationship between optic neuritis and the development of clinically definite multiple sclerosis. OBJECTIVE: To assess neurologic disability 10 to 12 years after an initial episode of optic neuritis. DESIGN: Longitudinal follow-up of a clinical trial. SETTING: Fourteen Optic Neuritis Treatment Trial clinical centers performed standardized neurologic examinations, including an assessment of neurologic disability. PARTICIPANTS: One hundred twenty-seven patients who had developed clinically definite multiple sclerosis. MAIN OUTCOME MEASURES: Functional Systems Scale and Expanded Disability Status Scale. RESULTS: The disability of most patients was mild, with 65% of patients having an Expanded Disability Status Scale score lower than 3.0. The degree of disability appeared to be unrelated to whether the baseline magnetic resonance imaging scan was lesion-free or showed lesions (P =.51). Among patients with baseline lesions, the degree of disability was unrelated to the number of lesions that were present on the scan (P =.14). Two patients died owing to severe multiple sclerosis, one of whom had no lesions revealed on the baseline scan. CONCLUSION: Most patients who develop clinically definite multiple sclerosis following an initial episode of optic neuritis will have a relatively benign course for at least 10 years.

Adult↗
PubMed2004

Latent nystagmus: vestibular nystagmus with a twist.

BACKGROUND: Latent nystagmus is a horizontal binocular oscillation that is evoked by unequal visual input to the 2 eyes. It develops primarily in humans with congenital esotropia. OBJECTIVE: To investigate the interrelationship between latent and peripheral vestibular nystagmus and their corollary neuroanatomical pathways. METHODS: Examination of subcortical neuroanatomical pathways producing latent nystagmus and review of the neurophysiological mechanisms by which they become activated in congenital esotropia. RESULTS: The vestibular nucleus presides over motion input from the eyes and labyrinths. Latent nystagmus corresponds to the optokinetic component of ocular rotation that is driven monocularly by nasal optic flow during a turning movement of the body in lateral-eyed animals. Congenital esotropia alters visual pathway development from the visual cortex to subcortical centers that project to the vestibular nucleus, allowing this primitive subcortical motion detection system to generate latent nystagmus under conditions of monocular fixation. CONCLUSIONS: Latent nystagmus is the ocular counterpart of peripheral vestibular nystagmus. Its clinical expression in humans proclaims the evolutionary function of the eyes as sensory balance organs.

Esotropia↗
PubMed2004

Optic radiation involvement in optic pathway gliomas in neurofibromatosis.

PURPOSE: Optic pathway gliomas (pilocytic astrocytomas) in neurofibromatosis type 1 (NF-1) typically involve some combination of the optic nerves, chiasm, or optic tracts. Involvement of the optic radiations is rare. DESIGN: This paper describes seven patients with NF-1 with gliomas involving the pregeniculate optic pathway in addition to the optic radiations. METHODS: A retrospective database review was made of all patients with NF-1 and optic pathway gliomas seen by one of the authors (G.T.L.) at the Children's Hospital of Philadelphia from July 1993 to October 2001. Patients with involvement of pregeniculate optic pathway and the optic radiations were identified. From November 2001 to February 2003, patients were sought prospectively. Cases were also identified from the practice of another author (M.C.B.) at Arkansas Children's Hospital. RESULTS: Four patients from Children's Hospital of Philadelphia (three of 83 total NF-1/optic pathway gliomas from July 1993 to October 2001 and one prospectively) and three from Arkansas Children's Hospital were identified. Two had expanding mass lesions within the white matter of the temporal or parietal lobes, which were histopathologically demonstrated to be pilocytic astrocytomas. The other five had radiographic involvement of the optic radiations but did not undergo biopsy. In three of the cases the vision was 20/200 or worse in each eye. CONCLUSIONS: Optic pathway gliomas in NF-1 may rarely involve the optic radiations. Optic radiation involvement may signal a more aggressive optic pathway glioma in patients with neurofibromatosis-1.

Child, Preschool↗
PubMed2004

Positive angle kappa: a sign of albinism in patients with congenital nystagmus.

PURPOSE: To determine whether the association of positive angle kappa and congenital nystagmus is a distinguishing feature of albinism. DESIGN: Observational case series. METHODS: Prospective examination of the location of the corneal light reflex in patients with albinism and idiopathic congenital nystagmus. RESULTS: A positive angle kappa in at least one eye was noted in 20/21 (95%) patients with albinism versus 4/12 (33%) patients with congenital nystagmus (P =.0003, Fisher exact test). A positive angle kappa in both eyes was noted in 15/21 (71.4%) patients with albinism versus 2/12 (16.6%) patients with idiopathic congenital nystagmus (P =.0039, Fisher exact test). CONCLUSION: A positive angle kappa in patients with congenital nystagmus is associated with albinism. The pathophysiology of the positive angle kappa may relate to the anomalous decussation of optic axons that characterizes the albinotic visual system.

Adolescent↗
PubMed2004

Microsaccadic opsoclonus: an idiopathic cause of oscillopsia and episodic blurred vision.

PURPOSE: To describe the clinical presentation and results of three-dimensional video-oculography of a patient with idiopathic microsaccadic opsoclonus. DESIGN: Observational case report. METHODS: Neuro-ophthalmologic examination and video-oculographic recording of horizontal, vertical, and torsional eye movements. RESULTS: A 67-year-old man with intermittent blurred vision and oscillopsia, which persisted with monocular occlusion, over a five year period was found to have high frequency, small amplitude back-to-back multivectorial saccadic movements which were visible with slit lamp biomicroscopy and direct ophthalmoscopy. Video-oculography showed a 20 Hz, 0.2 to 1 degree pattern of horizontal, vertical, and torsional microsaccades. This microsaccadic disorder has persisted for five years with no etiology. CONCLUSIONS: Microsaccadic opsoclonus is an idiopathic disorder that presents with oscillopsia and intermittent blurred vision. The diagnosis can be confirmed with three-dimensional eye movement recordings.

Aged↗
PubMed2004

Visual function more than 10 years after optic neuritis: experience of the optic neuritis treatment trial.

PURPOSE: To assess visual function more than 10 years after an episode of optic neuritis in patients enrolled in the Optic Neuritis Treatment Trial. DESIGN: Longitudinal follow-up of a randomized clinical trial. METHODS: Vision testing included measures of visual acuity, contrast sensitivity, and visual field. Quality of life was assessed with the National Eye Institute Visual Function Questionnaire. RESULTS: Examinations were completed on 319 patients. In most patients, visual function test results in the eyes that experienced optic neuritis at study entry ("affected eyes") were normal or only slightly abnormal after 9.9 to 13.7 years. Visual acuity in the affected eyes was >or=20/20 in 74%, 20/25 to 20/40 in 18%, <20/40 to 20/200 in 5%, and <20/200 in 3%. On average, visual function was worse in patients with multiple sclerosis (MS) than in those without MS. Recurrent optic neuritis in either eye occurred in 35% of patients. Such attacks were more frequent in patients with MS (P <.001). The National Eye Institute Visual Function Questionnaire scores were lower when visual acuity was abnormal and when MS was present. CONCLUSIONS: Most patients retained good to excellent vision more than 10 years after an attack of optic neuritis. Recurrences were more frequent in patients with MS.

Adolescent↗
PubMed2004

Reversible amantadine-induced corneal edema in an adolescent.

PURPOSE: To document reversible corneal edema caused by amantadine in a pediatric patient. METHODS: A 14-year-old boy with a neurologic tremor was referred for bilateral visual loss. Our examination disclosed bilateral corneal edema without ocular inflammation. Pachymetry confirmed significantly increased corneal thickness above 900 microm. RESULTS: Review of the patient's medical information revealed recent institution of amantadine as a means to control the patient's tremor. On cessation of this agent, rapid resolution of corneal edema and recovery of visual acuity occurred. Repeat pachymetry measurement revealed normal corneal thickness. CONCLUSION: In cases of corneal edema and in the absence of any identifiable ocular causes, a review of toxic effects of systemic medication should be undertaken. Amantadine can cause corneal decompensation and needs to be considered as part of the differential diagnosis of corneal edema.

Adolescent↗
PubMed2003

Heterozygous mutations of the kinesin KIF21A in congenital fibrosis of the extraocular muscles type 1 (CFEOM1).

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1; OMIM #135700) is an autosomal dominant strabismus disorder associated with defects of the oculomotor nerve. We show that individuals with CFEOM1 harbor heterozygous missense mutations in a kinesin motor protein encoded by KIF21A. We identified six different mutations in 44 of 45 probands. The primary mutational hotspots are in the stalk domain, highlighting an important new role for KIF21A and its stalk in the formation of the oculomotor axis.

Amino Acid Sequence↗