Non-hepatic hyperammonaemia: an important, potentially reversible cause of encephalopathy.

The clinical syndrome of encephalopathy is most often encountered in the context of decompensated liver disease and the diagnosis is usually clear cut. Non-hepatic causes of encephalopathy are rarer and tend to present to a wide range of medical specialties with variable and episodic symptoms. Delay can result in the development of potentially life threatening complications, such as seizures and coma. Early recognition is vital. A history of similar episodes or clinical risk factors and early assessment of blood ammonia levels help establish the diagnosis. In addition to adequate supportive care, investigation of the underlying cause of the hyperammonaemia is essential and its reversal, where possible, will often result in complete recovery. Detection of an unborn error of metabolism should lead to the initiation of appropriate maintenance therapy and genetic counselling.

The effect of intravenous aminophylline on essential tremor.

AIMS: The effects of intravenous aminophylline (375 mg) or placebo (saline) were studied in 10 patients with benign essential tremor. METHODS: This was a single-blind crossover study. Patients received aminophylline by i.v. infusion over 15 min or saline at least 1 week apart. Tremor was measured by a peizoresistive accelerometer at 15 min intervals predose and up to 2 h. Plasma theophylline concentrations were measured by h.p.l.c. RESULTS: Tremor power was significantly greater following aminophylline (5.67-6.2 Hz) than placebo (5.6-5.9 Hz). CONCLUSIONS: We conclude that intravenous aminophylline potentiates benign essential tremor when given acutely by the intravenous route in the doses required to achieve therapeutic benefits in asthma.

Motor neurone disease serum and beta-N-methylamino-L-alanine stimulate thyrotrophin-releasing hormone production by cultured brain cells.

We have investigated the effects of serum from patients with motor neurone disease (MND) and of the plant-derived excitotoxin beta-N-methylamino-L-alanine (L-BMAA) on thyrotrophin-releasing hormone (TRH) and somatostatin (SS) production by fetal rat brainstem cell cultures. Compared to age- and sex-matched normal and neurological disease control sera, MND sera produce a 2- to 3-fold increase in TRH content of the cultures with no change in SS levels. L-BMAA produced similar dose-related and stereospecific effects on the cultures increasing TRH levels to 2-fold with no effect on SS levels. These findings may be relevant to the understanding of the aetiology of MND.

Peripheral neuropathy during longterm high-dose amiodarone therapy.

Three patients developed peripheral neuropathy after taking amiodarone for more than 18 months. All had high serum concentrations of amiodarone and its desethyl metabolite; in one patient concentrations in a sural nerve biopsy were 80 times higher than in serum. Peripheral neuropathy is a complication of large doses of amiodarone taken over long periods.

Brachial plexus injury after median sternotomy.

Five patients are described with brachial plexus injuries complicating median sternotomy for cardiac surgery. The lower roots (medial cord) of the plexus were most affected and in some cases the lesions were bilateral. Pain was a prominent feature and although motor and sensory symptoms both occurred, motor signs were more prominent than objective sensory loss. Recovery was protracted and sometimes incomplete. Traction or compression of the plexus (or both) are the major possible mechanisms of injury; our experience and that of others suggests that traction is the more probable mechanism.

Radioimmunoassay of brain-type creatine kinase-BB isoenzyme in human tissues and in serum of patients with neurological disorders.

A sensitive radioimmunoassay for human brain type creatine kinase-BB isoenzyme has been used to measure the protein in serum as a potential index of central nervous system damage in patients with neurological disorders. The MB form of the enzyme (but not the MM form) partially cross-reacts in the radioimmunoassay but shows non-parallel dilution characteristics which distinguish it from the BB form of the enzyme. A survey of human tissues shows immunoreactive creatine kinase-BB in all human organs, with intestine and prostate approaching 35% of the brain concentration in contrast to the particularly low levels found in skeletal muscle, liver, spleen, and erythrocytes. No serum factors interfering in the assay were detected, and the normal serum level of creatine kinase-BB was found to be approximately 1-3 ng/ml. Serum containing high levels of immunoreactivity showed dilution characteristics paralleling the standard curve in the radioimmunoassay. Measurements of the protein in 47 patients with a variety of neurological disorders showed significantly raised mean levels in patients with dementia and with head injuries, isolated raised levels were also found in other disorders.

Immunoreactive aldolase C in cerebrospinal fluid of patients with neurological disorders.

Nervous-system specific aldolase C has been detected in human cerebrospinal fluid (CSF) by radioimmunoassay. Measurement of 138 samples of CSF showed a mean level of 92 +/- 28 ng/ml. There was no correlation between the level of CSF aldolase C and the CSF total protein, albumin, IgG, or IgA levels. Aldolase C immunoreactivity present in concentrated CSF diluted out in parallel with the standard curve in the assay and showed an elution profile on ion-exchange and gel filtration chromatography similar to that of aldolase present in whole human brain extracts. Addition of known quantities of purified aldolase C4 to CSF gave quantitative recovery on subsequent radioimmunoassay. Measurement of aldolase C in the CSF of 66 patients with neurological disorders showed several patients with levels considerably in excess of 120 ng/ml, but there was no statistically significant difference in the mean levels between groups of patients with different diseases.