Giant axonal neuropathy: visual and oculomotor deficits

Optic Atrophy in End-Stage Giant Axonal Neuropathy: A Case Report

A 32-year-old woman with a history of biopsy-proven giant axonal neuropathy (GAN) and no past ocular history presented after failing a vision-screening test conducted by her primary doctor. Bilateral optic atrophy was observed on fundus examination with cup-to-disc ratio of 0.7. Kinetic visual fields showed moderate constriction in both eyes. Optical coherence tomography (OCT) of the retinal nerve fibre layer (RNFL) exhibited diffuse thinning, a pattern atypical of glaucomatous or nutritional optic atrophy and most likely secondary to the optic atrophy associated with GAN. Serial OCT to monitor RNFL thickness may offer a non-invasive means of monitoring progression in GAN for future therapeutic studies.

Giant axonal neuropathy with predominant central nervous system manifestations

The authors describe a 25-year-old woman with giant axonal neuropathy (GAN) and severe CNS involvement. She had been admitted to hospital with generalized seizures, and had gait disturbances followed by progressive mental deterioration since childhood. Neurological examination revealed mental retardation, scanning speech, cerebellar dysfunction, pyramidal signs, mainly in the lower extremities, and peripheral sensory neuropathy. Sensory nerve conduction velocity was decreased; brain CT and MRI showed diffuse demyelination. Sural nerve biopsy revealed characteristic signs of GAN. The patient's older sister had died at the age of 23, after having had similar neurological disturbances since childhood. This case illustrates an unfamiliar presentation of GAN, characterized by mild sensory neuropathy and serve CNS involvement, including seizures.

Anaesthesia for a patient with giant axonal neuropathy

Giant axonal neuropathy is a generalised disorder of cytoplasmic intermediate filaments which particularly involves the peripheral and central nervous systems. In this paper we describe a child with giant axonal neuropathy and discuss the anaesthetic management in the light of the pathology and physiology of the condition.

Giant axonal neuropathy: clinical, electrophysiologic, and neuropathologic features in two siblings

Giant axonal neuropathy is a progressive central-peripheral axonopathy characterized by distention of axons by aggregated neurofilaments. We report two female siblings with giant axonal neuropathy. Both patients developed symptoms of a chronic progressive polyneuropathy at age 3 years. Clinical evidence of central nervous system involvement was present in both cases. Autopsy neuropathologic examination of the older sibling at the age of 11 years revealed numerous giant axons, Rosenthal fibers, and gliosis throughout the brain and spinal cord and typical giant axons in the peripheral nerves. Electrophysiologic studies in the younger sibling indicated brain stem dysfunction, and her sural nerve biopsy revealed enlarged axons packed with neurofilaments. These patients illustrate that neurologic deficits of giant axonal neuropathy result from widespread lesions in the central, as well as peripheral (including autonomic), nervous systems. This occurrence of giant axonal neuropathy in two siblings supports a genetic origin of this disease. This is the first report of autopsy findings in giant axonal neuropathy in an affected sibling.

Childhood giant axonal neuropathy. Case report and review of the literature

Giant axonal neuropathy (GAN) is a rare autosomal recessive childhood disorder characterized by a peripheral neuropathy and features of central nervous system involvement. Typically seen are distal axonal swellings filled with 8-10 nm in diameter neurofilaments in central and peripheral axons, and intermediate filament collections in several other cell types. Many neurotoxins produce a morphologically similar neuropathy in humans and experimental animals. Defective nerve fiber energy metabolism has been postulated as a cause in these toxic neuropathies. It is possible that GAN represents an inborn error of metabolism of enzyme-linked sulfhydryl containing proteins, resulting in impaired production of energy necessary for the normal organization of intermediate filaments.

Giant axonal neuropathy: central abnormalities demonstrated by evoked potentials

Previous studies of giant axonal neuropathy have reported clinical and pathological findings that indicate involvement of the central nervous system. We studied 3 boys with giant axonal neuropathy, who were 14 to 16 years of age, using auditory, visual, and somatosensory evoked potentials. Absence of waveforms and prolongation of peak and interwave latencies were found. Abnormalities were noted in all modalities. The auditory brainstem evoked response in particular indicated a significant increase in brainstem conduction time. These studies add clinical neurophysiological confirmation of the central nervous system involvement in this disorder and may also provide a means of quantitative evaluation of its progression.

Hereditary motor sensory neuropathy type II with neurofilament accumulation: new finding or new disorder?

Peroneal muscular atrophy is now known to be heterogeneous and to be due to various underlying genetic mechanisms. Exploring this heterogeneity further, we report on a German kinship with the clinical, genetic, and nerve conduction features of hereditary motor and sensory neuropathy type II (HMSN type II) but whose sural nerves on biopsy were found to show infrequent axonal swellings with neurofilament accumulations not previously described. The dominant inheritance and absence of kinky hair set this disorder apart from giant axonal neuropathy. There was no history of toxic exposure to industrial chemicals. We conclude that the disorder either is a new type of HMSN or is HMSN type II with previously unencountered neurofilament accumulations. Neurofilament accumulation indicates that the axon could be a site for primary derangement and may implicate an abnormality of slow axonal flow. In addition, some of the patients exhibited features suggestive of a cardiomyopathy.

Giant axonal neuropathy: a conditional mutation affecting cytoskeletal organization

Giant axonal neuropathy (GAN) results from autosomal recessive mutations (gan-) that affect cytoskeletal organization; specifically, intermediate filaments (IFs) are found collapsed into massive bundles in a variety of different cell types. We studied the gan- fibroblast lines WG321 and WG139 derived from different GAN patients. Although previous studies implied that the gan- IF phenotype was constitutive, we find that it is conditional. That is, when cells were grown under the permissive condition of medium containing over 2% fetal calf serum, most cells had normal IF organization. IF bundles formed when gan- cells were transferred to the nonpermissive condition of low (0.1%) serum. Microtubule organization appeared normal in the presence or absence of serum. The effect of serum starvation was largely blocked or reversed by the addition of BSA to the culture media. We found no evidence that the gan- phenotype depends upon progress through the cell cycle. We discuss the possible role of serum effects in the etiology of GAN and speculate as to the molecular nature of the gan- defect.

Giant axonal neuropathy: an inborn error of organization of intermediate filaments

Light microscopic examination of cultured skin fibroblasts from three patients with giant axonal neuropathy (GAN) revealed large aggregates of intermediate filaments (IF). However, electrophoretic analysis of these cells showed normal amounts of vimentin, the fibroblast IF subunit protein. The isoelectric point and peptide mapping of vimentin were identical to controls. Moreover, vimentin was synthesized and phosphorylated at a normal rate. These findings demonstrate that GAN is an inborn error of the organization of IF and suggest that the basic genetic defect in GAN does not involve primarily the IF subunit proteins.

Clinical progression of giant-axonal neuropathy over a twelve year period

Giant-axonal neuropathy (GAN), a chronic peripheral neuropathy with associated Central Nervous System dysfunction and tight curly hair, is described in a 17-year-old girl. Biopsies of this girl's muscle and nerve are characteristic of this condition. Her clinical course over a 12 year period characterizes a disease of a slowly progressive nature.