Myasthenia gravis in children: analysis of 18 patients.

Myasthenia gravis (MG) in childhood is rare comprising 10 to 20 % of all myasthenic patients. We studied 18 patients with MG whose first symptoms started from 1 to 12 years of age, followed at the Department of Neurology of the UNIFESP-EPM, from January 1983 to August 1997. There were 10 girls and 8 boys (1.2:1). Eleven patients (61%) presented moderate or severe generalized disease and 4 (22%) had at least one myasthenic crisis. EMG with supramaximal repetitive nerve stimulation was diagnostic in 8 (47%) out of 17 patients, and chest CT was normal in 14 patients. Seropositivity to acetylcholine receptor antibodies was found in 81.6% (9 out of 11 tested) and the levels had no relation to clinical severity. Nine out of 16 patients (56%) worsened with pyridostigmine alone and were treated with prednisone. Four out of those nine continued worsening despite steroids and were subjected to thymectomy (all showed thymic lymphoid follicular hyperplasia). Three patients (75%) improved markedly after thymectomy and one (25%) worsened, eventually getting better with intravenous immunoglobulin and oral azathioprine. MG treatment, using all resources available, has to be individualized for each child.

Fatal rhabdomyolysis after acute sodium monensin (Rumensin) toxicity: case report.

Myoglobinuria or rhabdomyolysis occurs when myoglobin escapes into the blood and then into the urine after acute muscle necrosis. It can be a serious medical condition leading to renal failure and death. There are many causes including exertion, crush syndromes, ischaemia, metabolic disorders, exogenous toxins and drugs, heat stroke and hereditary disorders such as malignant hyperthermia. We report the case of a 17 year-old boy who developed myoglobinuria, renal failure and death 11 days after ingesting sodium monensin, possibly with the intention of developing muscles. Sodium monensin, the active principle of Rumensin(R), is a dietary additive used as a growth promoter for confined cattle. There are no previous reports of human intoxication. Accidental or experimental sodium monensin intoxication in animals produces similar findings to those seen in this case.

Wrist and palm indexes in carpal tunnel syndrome.

According to median sensory latency >/= 3.7 ms (wrist-index finger [WIF], 14 cm), median/ulnar sensory latency difference to ring finger >/= 0.5 ms (14 cm) or median midpalm (8 cm) latency >/= 2.3 ms (all peak-measured), 141 Brazilian symptomatic patients (238 hands) have CTS confirmation. Wrist ratio (depth divided by width, WR) and a new wrist/palm ratio (wrist depth divided by the distance between distal wrist crease to the third digit metacarpophalangeal crease, WPR) were measured in all cases. Previous surgery/peripheral neuropathy were excluded; mean age 50.3 years; 90.8% female. Control subjects (486 hands) have mean age 43.0 years; 96.7% female. The mean WR in controls was 0.694 against 0.699, 0.703, 0.707 and 0.721 in CTS groups of progressive WIF severity. The mean WPR in controls was 0.374 against 0.376, 0.382, 0.387 and 0.403 in CTS groups of WIF progressive severity. Both were statistically significant for the last two groups (WIF > 4.4 ms, moderate, and, WIF unrecordable, severe). BMI increases togetherwith CTS severity and WR. It was concluded that both WR/WPR have a progressive correlation with the severity of CTS but with statistically significance only in groups moderate and severe. In these groups both WR and BMI have progressive increase and we believe that the latter could be a risk factor as important as important WR/WPR.

A novel myopathy-associated mitochondrial DNA mutation altering the conserved size of the tRNA(Gln) anticodon loop.

We report a novel mitochondrial DNA alteration in a 12-year-old boy with myopathy. We identified a single nucleotide insertion (an adenine) in the mitochondrial tRNA-glutamine gene. This addition of an additional adenine in a polyadenine stretch (at mitochondrial DNA positions 4366-4369), alters the length of the evolutionary conserved anticodon loop from seven to eight bases. The nt-4370 addition was heteroplasmic and was abundant in the patient's muscle. Lower proportions of mutated mitochondrial DNA were observed in skin fibroblasts, but were below detectable levels in white blood cells. A muscle biopsy of the patient showed ragged red fibers and an unusually high percentage of cytochrome c oxidase-deficient fibers (89%). The pathogenicity of the mutation was also evident by the fact that fibers harboring lower levels of the mutation showed normal cytochrome c oxidase activity. The insertion in the anticodon loop of tRNA(Gln) gene identified in our patient may provide a unique tool to study protein synthesis in human mitochondria.

[Distal renal tubular acidosis presenting with rhabdomyolysis]. / Acidose tubular renal distal manifestando-se com rabdomiólise.

Severe hypokalemia is an uncommon cause of rhabdomyolysis. We describe a patient, 28-year-old woman, with distal renal tubular acidosis (DRTA) who developed severe hypokalemia and rhabdomyolysis. Muscle biopsy shows focal muscular necrosis mainly in type II muscle fibers and mild macrophagic reaction. After correcting the acidosis with oral administration of alkalinizing salts, clinical and laboratory improvement was seen. This clearly establish a causal relationship between the positive acid balance, hypokalemia and the muscular manifestation in DRTA.

Isolated and painless infraspinatus atrophy in top-level volleyball players. Report of two cases and review of the literature.

Isolated and painless infraspinatus atrophy and weakness are described in two top-level volleyball players. EMG revealed isolated denervation of the infraspinatus muscle. One athlete continued playing and his clinical features have not changed. The other recovered her muscle bulk and strength after stopping playing. These findings were attributed to intense activity of the shoulder joint, without any direct trauma. On clinical grounds, we did not consider these cases as true examples of entrapment neuropathy. Pathogenesis was related to traction of the distal branch of the suprascapular nerve during the act of reception of the ball ("Manchete").