Vecuronium-associated axonal motor neuropathy: a variant of critical illness polyneuropathy?

Neuromuscular blocking agents are routinely used as an adjunct therapy for critically ill patients. Unlike many neuromuscular blocking agents, vecuronium does not cause significant histamine release, which may lead to bronchoconstriction. Due to a short duration of action and limited accumulation, vecuronium has been widely used. Prolonged ventilatory dependence due to persistent neuromuscular blockade has been reported in patients treated with vecuronium. We report a case of an 8-year-old girl who had a primarily motor axonopathy presenting with weakness after extended vecuronium administration with prolonged course of recovery. This primarily motor neuropathy with axonal features may be a variant of critical illness polyneuropathy, a rarely reported condition in pediatric patients.

Solitary intramedullary neurosarcoidosis: role of MRI in early detection.

BACKGROUND: Intramedullary neurosarcoidosis may be the first manifestation of the disease and may mimic a tumor clinically and radiographically. Two patients who presented with cervical intramedullary lesions on magnetic resonance imaging (MRI) scans were found to have neurosarcoidosis. CLINICAL PRESENTATION: Two patients with negative past medical history presented with progressive myelopathic features, and intramedullary cervical lesions were detected on MRI scan; the diagnosis was made on biopsy of the lesions. Early therapeutic intervention led to a favorable outcome. CONCLUSION: Intra-medullary neurosarcoidosis, especially in the cervical cord, can be the initial presentation of the disease, mimicking a tumor. MRI scan, biopsy, and, in fewer cases, angiotensin-converting enzyme levels can help with the diagnosis and may lead to a favorable outcome.

Congenital cervical spinal atrophy: an intrauterine hypoxic insult.

We present two patients with congenital cervical spinal atrophy who were born at 37 and 33 weeks of gestation. Both patients were unrelated and had no family history of neuromuscular diseases. They presented at birth with arthrogryposis multiplex and symmetrical severe muscle weakness and wasting confined to the upper extremities. There was no sensory or bulbar symptom. Electromyography showed polyphasic and fast-firing units in the proximal muscles of the upper extremities. With the evidence of chronic denervation and re-innervation, we speculate that this static condition is most likely due to circulatory insufficiency causing anterior horn cell ischemia during the latter part of the first trimester.

Neuromyotonia: autoimmune pathogenesis and response to immune modulating therapy.

BACKGROUND: Neuromyotonia (NMT) has been postulated to be an autoimmune channelopathy, probably by affecting voltage gated potassium channels (VGKC) leading to excitation and abnormal discharges [Sinha et al., Lancet 338 (1991) 75]. OBJECTIVE: To report three patients with NMT who had other associated immune-mediated conditions, i.e., myasthenia gravis, thymoma and various types of peripheral neuropathies. One patient had peripheral neuropathy and involvement of pre- and post-synaptic neuromuscular junction. RESULTS: All three patients had evidence of polyneuropathy and neuromyotonic discharges on electrodiagnostic studies. Elevated acetylcholine receptor antibodies were noted in all patients and malignant thymoma was found in two patients with metastasis. All three patients showed moderate to marked response to plasma exchange. CONCLUSIONS: These findings strongly suggest a humoral autoimmune pathogenesis of NMT, probably by K(+) channel involvement, affecting acetylcholine quantal release and postsynaptic membrane. Clinicians should be aware of this association of immune-mediated conditions in NMT patients and marked improvement with plasma exchange.

Toxoplasmic polymyositis revisited: case report and review of literature.

Toxoplasmosis can cause polymyositis either by reactivation or by recent infection. Inconsistent response to antiprotozoal therapy has been the strongest argument against toxoplasmic polymyositis as a separate entity. We report a biopsy-proven case of toxoplasmic polymyositis in a cardiac transplant patient presenting with a severe proximal weakness, myopathic, electromyographic changes and ten-fold increase of anti-Toxoplasma antibodies. An early antiprotozoal therapy and plasmapheresis led to recovery. A review of previously reported cases of toxoplasmic polymyositis suggests that an early antiprotozoal therapy is the most important variable affecting the outcome of this disease. We propose that toxoplasmic polymyositis has two phases: acute, responsive to antiprotozoal therapy, and chronic, manifested by altered immune response requiring steroids. We suggest that all patients presenting with polymyositis should have serological tests for toxoplasmosis as a part of their initial evaluation and an early trial of antiprotozoal therapy in case of positive findings.

Unexpected recovery in a newborn with severe hypomyelinating neuropathy.

We report the case of a severely hypotonic and weak term newborn who required ventilatory support from the time of birth. Serial neurophysiologic studies were consistent with severe demyelinating polyneuropathy. The infant's condition deteriorated over several weeks despite treatment with corticosteroids and intravenous immunoglobulin (IVIG) for presumed inflammatory demyelinating polyneuropathy. Histopathologic findings in a sural nerve biopsy, however, were similar to those previously reported in congenital hypomyelinating neuropathies. After 12 weeks of hospitalization and after discontinuation of corticosteroids, the patient began to recover and required no further ventilatory support. Remarkable improvement has continued for 18 months. This patient raises questions about the underlying mechanisms of hypomyelinating neuropathies in early infancy.