Transient absence of F-waves in acute myelopathy: a potential source of diagnostic error.

BACKGROUND: The frequent absence of F-waves in lesions of the nerve roots and proximal nerve is well known, with absence of F-waves occasionally the only electrophysiologic manifestation of early Guillain-Barré Syndrome. It is less well known that acute central nervous system lesions can cause disappearance of F-waves. CASE DESCRIPTION: A 25 year old woman presented with quadriparesis and sensory loss progressive over several days. Hyporeflexia and hypotonia were present. Imaging studies were initially negative. Electrophysiologic testing was normal apart from the diffuse absence of F-waves. This led to strong consideration of the diagnosis of Guillain-Barré Syndrome, and treatment for this diagnosis. However, imaging studies ultimately revealed the diagnosis to be transverse myelitis. F responses normalized 6 weeks after the initial study. CONCLUSIONS: F responses are significantly modulated by central nervous system factors. The relevant experimental and clinical literature is reviewed. The relevance of this to the diagnosis of Guillain-Barré Syndrome has not been previously emphasized, but our experience confirms that the absence of F-waves in a patient with acute weakness accompanied by hyporeflexia and hypotonia does not distinguish between peripheral nerve and central nervous system lesions.

Endoneurial vasculitis and tubuloreticular inclusions in peripheral nerve biopsy.

We describe 3 patients in whom nerve biopsy revealed endothelial tubuloreticular inclusions in association with peripheral nerve endoneurial vasculitis. Two of the patients had systemic lupus erythematosus (SLE), while the third was HIV-positive. Review of our biopsy material featuring the much more common finding of epineurial vasculitis failed to disclose any instances in which endothelial tubuloreticular inclusions (TRIs) were present. We conclude that TRIs and endoneurial vasculitis are closely associated. Moreover, if detected on a nerve biopsy specimen, TRIs are very suggestive of SLE or HIV infection. Finally, literature evidence is cited to suggest that an "acid-labile" alpha-interferon may be pathogenically related to the vasculitic process in these patients, perhaps through a process mediated by tumor necrosis factor.

Vasculitic polyradiculopathy in systemic lupus erythematosus.

A 22 year old woman with recently diagnosed systemic lupus erythematosus presented with subacute progressive areflexic paraparesis, electrophysiologically identified as a pure axonal polyradiculopathy. Sural nerve biopsy disclosed necrotising vasculitis. A striking radiological feature was marked enhancement of the cauda equina with gadolinium.

Chronic inflammatory demyelinating polyradiculoneuropathy: unusual clinical features and therapeutic responses.

We present three patients with atypical chronic inflammatory demyelinating polyradiculoneuropathy and discuss the management of patients who appear treatment resistant or present with unusual manifestations. The clinical features of the patients included massive nerve root hypertrophy causing myelopathy and movement-provoked paresthesia, pupillary dysfunction, visual loss due to increased intracranial pressure, and focal brachial plexus involvement. Each patient ultimately required prolonged courses of immune modulating therapy before benefit was attained, illustrating the importance of intensive and prolonged treatment combined with objective assessment of response to therapy.

Rapid postanoxic calcification of the basal ganglia.

A 22-year-old male diabetic on hemodialysis suffered a cerebral anoxic event. Serial CT showed the development of basal ganglia calcification over a period of no more than 17 days. It appears that the basal ganglia may develop petechial hemorrhage, necrosis, calcification, or combinations of these following an anoxic insult. The neuropathologic substrate and mechanism of rapid postanoxic calcification are unknown.

Adult peripheral neuroepithelioma in Meckel's cave.

A case of peripheral neuroepithelioma arising from the trigeminal nerve in Meckel's cave is presented. The discussion emphasizes the pathological criteria for the diagnosis of a peripheral neuroepithelioma and the current controversy about the classification of this and related tumors.