The Inverse Lhermitte Phenomenon Suggests Nitrous Oxide-Induced Myelopathy: Case Report and Review of the Literature.

Nitrous oxide-induced myelopathy is a relatively well-known clinical entity. Less well-known, however, is the rare inverse Lhermitte phenomenon, where neck flexion elicits an ascending, rather than descending, electric shock-like sensation. This is a characteristic symptom and sign that may occur in nitrous oxide toxicity. In this article, we present the case of a patient who was admitted to our hospital with suspected Guillain-Barré syndrome due to her ascending numbness and unsteady gait. We describe her examination and laboratory features leading to the correct diagnosis, along with a historical review of the various subtypes of the Lhermitte phenomenon and the pathophysiology of nitrous oxide-induced myelopathy.

Migraine with prolonged aphasic aura associated with a CACNA1A mutation: A case report and narrative review.

OBJECTIVE: To demonstrate that a known CACNA1A variant is associated with a phenotype of prolonged aphasic aura without hemiparesis. BACKGROUND: The usual differential diagnosis of prolonged aphasia without hemiparesis includes vascular disease, seizure, metabolic derangements, and migraine. Genetic mutations in the CACNA1A gene can lead to a myriad of phenotypes, including familial hemiplegic migraine (FHM) type 1, an autosomal dominant disorder characterized by an aura of unilateral, sometimes prolonged weakness. Though aphasia is a common feature of migraine aura, with or without hemiparesis, aphasia without hemiparesis has not been reported with CACNA1A mutations. METHODS: We report the case of a 51-year-old male who presented with a history of recurrent episodes of aphasia without hemiparesis lasting days to weeks. His headache was left sided and was heralded by what his family described as "confusion." On examination, he had global aphasia without other focal findings. Family history revealed several relatives with a history of severe headaches with neurologic deficits including aphasia and/or weakness. Imaging revealed T2 hyperintensities in the left parietal/temporal/occipital regions on MRI scan with corresponding hyperperfusion on SPECT. Genetic testing revealed a missense mutation in the CACNA1A gene. CONCLUSIONS: This case expands the phenotypic spectrum of the CACNA1A mutation and FHM to include prolonged aphasic aura without hemiparesis. Our patient's SPECT imaging demonstrated hyperperfusion in areas correlating with aura symptoms which can occur in prolonged aura.

Nerve entrapments related to muscle herniation.

BACKGROUND: Muscle herniation is a muscle protrusion through a fascial defect. It is a rarely reported cause of nerve entrapment. METHODS: We present a case of superficial fibular (peroneal) neuropathy associated with a fibularis (peroneus) brevis muscle herniation and a review of the literature on nerve entrapments secondary to muscle herniation unrelated to compartment syndrome. RESULTS: Eleven cases of nerve entrapments secondary to muscle herniation were identified. The superficial fibular nerve (SFN) was the most commonly entrapped nerve by fibularis muscle herniation. Patients presented with pain, numbness, or paresthesias, and an often tender, small palpable mass with a Tinel sign. Muscle MRI or ultrasound identified the lesion, and patients responded well to fasciotomy. CONCLUSIONS: The most commonly reported nerve entrapped by muscle herniation is the SFN secondary to fibularis muscle herniation. Characteristic clinical and imaging (MRI or ultrasound) features are diagnostic, and there is a salutary response to fasciotomy.

Pain, Headache, and Other Non-motor Symptoms in Myasthenia Gravis.

PURPOSE OF REVIEW: Myasthenia gravis (MG) is traditionally conceptualized as a disease with purely motor manifestations. This paper reviews the supporting evidence and pathophysiology of non-motor symptoms in MG, including pain, headache, special sense and autonomic dysfunction, sleep disturbance, and cognitive and psychosocial issues. RECENT FINDINGS: Work in this area has been limited. Recent studies have identified bodily pain and headache as common complaints in patients with MG. A growing literature also suggests that there may be an association of MG and sleep disturbance (both obstructive sleep apnea and sleep cycle dysfunction). Few studies suggest some measurable abnormalities of olfaction, gustation, audition, and autonomic function. The cognitive and psychosocial aspects of MG represent an emerging area of clinical and research interest, but large-scale data is sparse in the USA. The pathophysiology of MG is complex, and our understanding of the immunologic basis of this disease is expanding. The classic view of MG as a purely motor disorder may be incomplete. Recent work highlights non-motor symptoms that may impact patient management and quality of life.

Headache and Pain in Guillain-Barré Syndrome.

While moderate and severe back or extremity pain is frequent in Guillain-Barré syndrome (GBS), headache appears to be uncommon. Most of the reports of headache in GBS place it in the context of the posterior reversible encephalopathy syndrome (PRES) which is increasingly recognized as a likely dysautonomia-related GBS complication. There are also a few reports of headache in the setting of increased CSF pressure and papilledema and in association with the Miller Fisher GBS variant. In comparison, back and extremity pain is highly prevalent. Aching muscle pain and neuropathic pain are the two most common of several pain types. Pain may be a heralding feature and has been described in patients as long as 2 years after disease onset. Pain management is a major axis of treatment in GBS. Gabapentin is a reasonable first-line choice, and opioid medications can be added for more severe pain but there are few clinical trials to inform specific recommendations. While the understanding of pain pathophysiology in GBS is incomplete, its prevalence and clinical impact are increasingly recognized and studied. Pain should be considered a cardinal manifestation of GBS along with acute, mostly symmetric weakness and diminished reflexes.

Optochiasmatic and peripheral neuropathy due to ethambutol overtreatment.

Ethambutol is known to cause optic neuropathy and, more rarely, axonal polyneuropathy. We characterize the clinical, neurophysiological, and neuroimaging findings in a 72-year-old man who developed visual loss and paresthesias after 11 weeks of exposure to a supratherapeutic dose of ethambutol. This case demonstrates the selective vulnerability of the anterior visual pathways and peripheral nerves to ethambutol toxicity.

Neuropathic cachexia associated with type 1 diabetes in an adolescent girl.

BACKGROUND: Diabetic neuropathic cachexia is a rare and little understood variant of diabetic neuropathy. It predominantly affects men with type 2 diabetes mellitus in their sixth to seventh decades of life and is characterized by the subacute onset of a painful sensory neuropathy, rapid weight loss, and psychiatric comorbidity. METHODS: We present the only female pediatric case described to date, and one of only a handful of cases reported to affect type 1 diabetics. RESULTS: In this patient a diagnosis of diabetic neuropathic cachexia was based on the rapid onset of severe allodynic pain, polyneuropathy, and marked weight loss in the setting of poorly controlled diabetes, without evidence of end-organ disease and exclusion of other known causes of neuropathy. CONCLUSIONS: Diabetic neuropathic cachexia is a complex neuroendocrinologic disorder characterized by profound weight loss, neuropathic pain, and mood disturbance. Electrodiagnostic abnormalities were pronounced showing a moderately severe generalized sensorimotor polyneuropathy.

Teaching video neuroimages: orthostatic tremor: the helicopter sign.

A 63-year-old man presented with 4 years of orthostatic tremor while standing, resolving after sitting or leaning against a wall. There was marked subjective unsteadiness, but no falls. Surface EMG in arms and legs demonstrated a 14- to 16-Hz synchronous tremor in antagonist muscles (video on the Neurology Web site at www.neurology.org.).

Optic neuritis and palatal dysarthria as presenting features of post-infectious GQ1b antibody syndrome.

A 31-year-old man had optic neuritis 2 weeks after a diarrheal illness, followed by several deficits including palatal dysarthria, diplopia, ataxia, sensory dysfunction, and mild dysautonomia. Brain MRI and CSF were normal. Nerve conduction studies were initially normal and subsequently showed mild reduction in sensory amplitudes. Anti-GQ1b IgG titer was positive. Deficits resolved after treatment with IVIg. This clinical constellation represents an overlap between Miller Fisher syndrome (MFS) and the pharyngeal-cervical-brachial (PCB) variant of Guillain-Barre syndrome (GBS), along with the infrequently reported central feature of optic neuritis. Campylobacter jejuni enteritis may have triggered the syndrome by molecular mimicry. GQ1b antibodies are associated with MFS, GBS, Bickerstaff brainstem encephalitis and PCB; they form an overlapping spectrum of features, hence the anti-GQ1b syndrome.

Occupational manganese neurotoxicity provoked by hepatitis C.

Manganese neurotoxicity developed in a highly exposed worker after asymptomatic, moderate hepatic dysfunction from hepatitis C infection. Antiviral therapy was accompanied by resolution of increased blood manganese levels and neurologic improvement. Even asymptomatic hepatic dysfunction may impair manganese clearance and place highly exposed persons at risk for toxicity.

Carpal tunnel syndrome in older adults.

The clinical and electrophysiologic characteristics of carpal tunnel syndrome (CTS) in elderly adults are not well established. We examined age differences in clinical, functional, and electrophysiologic features in elderly adults referred to a neuromuscular service for evaluation of symptoms suggestive of CTS. Of 415 consecutive subjects referred over an 18-month period, 343 met clinical criteria for CTS. There were 158 young (or=65 years). There were no age differences in the duration of CTS symptoms, hand function, or presence of autonomic symptoms. The elderly adults had a higher prevalence of thenar weakness and thenar atrophy than younger subjects. Electrophysiologic abnormalities were more common and more severe in the older subjects. Our study shows that although there are no age differences in subjective complaints of CTS, older adults had objective clinical and electrophysiologic evidence of a more severe median nerve entrapment. The findings suggest that greater attention needs to be paid to objective evidence of CTS severity rather than subjective complaints when evaluating elderly adults presenting for clinical evaluation of CTS.

Methyl bromide intoxication causes reversible symmetric brainstem and cerebellar MRI lesions.

Methyl bromide is toxic to the central and peripheral nervous systems. A patient with occupational exposure to this agent is described. MRI showed strikingly symmetric brainstem and cerebellar lesions. The patient's clinical course and the topography and resolution of his MRI abnormalities suggest that this condition is an energy deprivation syndrome.