Recurrent Guillain-Barré syndrome: lightning does strike twice.

Recurrent Guillain-Barré syndrome following a long asymptomatic interval is very rare. Forty-nine cases are reviewed from the literature, their common features are noted and conclusions are drawn. Thus it can be seen that, with Guillain-Barré syndrome, lightning can indeed strike twice.

Magnetic resonance imaging of the brain in phenylketonuria.

Abnormalities of magnetic resonance imaging (MRI) of the brain occur in some patients with phenylketonuria but the clinical importance of this finding is not clear. In order to determine the frequency and functional significance of changes on MRI we investigated 77 adolescent and adult patients with phenylketonuria. Patients aged 14-49 years and taking a restricted diet of 1 g/kg protein underwent clinical examination, IQ testing, neurophysiological investigation, and MRI of the brain. Patients aged between 10-14 years taking a low phenylalanine diet with amino acid supplements had MRI of the brain only. Biochemical control was assessed from: the lifetime blood phenylalanine determined from the mean blood concentration throughout life; the accumulated time for each patient that phenylalanine was < 120 mumol/L; the accumulated time for each patient that phenylalanine was > 1200 mumol/L); mean blood concentration in the first 4 years of life; and the mean blood phe concentration in the 5 years prior to imaging. MRI changes, compatible with a disturbance in the water content of white matter, were present in all but 1 patient. The severity of abnormality was most strongly associated with the blood phenylalanine concentration at the time of imaging. Clinical and neurophysiological abnormalities were less common and usually mild. 3 patients had prolonged central motor conduction time, 7 had prolonged visual evoked potentials, and 5 had impaired peripheral sensory nerve conduction. There was no significant association between the extent of MRI abnormalities and IQ, and the presence of neurophysiological, or clinical abnormalities. An abnormal brain scan in PKU may reflect present biochemical control rather than indicate significant neurological damage. As yet there is little evidence that in most patients with PKU these MRI changes are of clinical importance.

Paraspinal muscle fibrosis: a specific pathological component in ankylosing spondylitis.

The histological appearance of percutaneous superficial paraspinal muscle biopsy specimens from eight patients with ankylosing spondylitis was compared with that of biopsy specimens from 13 control patients with similar degrees of disability and spinal immobility due to severe, chronic mechanical back pain. In both groups marked type II muscle fibre atrophy was shown. Additionally, in patients with ankylosing spondylitis there were obvious increases in perifibre connective tissue in association with central migration of cell nuclei but without evidence of inflammation. Qualitative electromyography failed to show denervation changes in either group. Paraspinal muscle fibrosis, occurring over and above atrophic changes due to disuse, seems to be a specific pathological component of ankylosing spondylitis which may be of particular importance in early disease as it may contribute towards back stiffness and weakness.

No sensory neuropathy during pyridoxine treatment in homocystinuria.

Seventeen patients with cystathionine synthase deficiency homocystinuria were examined clinically and neurophysiologically for evidence of sensory neuropathy. All had received high dose pyridoxine (vitamin B-6) for many years. Absence of neurological disturbance in all cases suggests long term treatment with pyridoxine in the dosages used in homocystinuric patients is not harmful.

Effect of aldose reductase inhibition on resistance to ischemic conduction block in diabetic subjects.

OBJECTIVE: To study the effect of aldose reductase inhibition with ponalrestat on resistance to ischemic conduction block (RICB) in diabetic subjects. RESEARCH DESIGN AND METHODS: Twenty-one healthy diabetic subjects without neuropathy were studied. Subjects were randomized to take either a double-blind trial of 600 mg ponalrestat or placebo once daily for 6 wk. The median nerve action potential (MNAP) and conduction velocity (NCV), before and after 20 min of forearm ischemia, were measured at the start and finish of the study. RESULTS: RICB (MNAP remaining after ischemia) decreased from 39.5 to 29.4% in the ponalrestat-treated group (P less than 0.05) and increased from 48.1 +/- 10.2 to 49.5 +/- 6.5% in the placebo-treated group. MNAP and NCV were unchanged in both groups. CONCLUSIONS: Aldose reductase inhibition with ponalrestat partly reverses RICB in diabetes, perhaps by improving nerve hypoxia or reducing nerve energy substrates.

Carpal tunnel syndrome in the mucopolysaccharidoses and related disorders.

Eighteen patients with various mucopolysaccharidoses or mucolipidosis III were studied electrophysiologically to determine the presence or absence of carpal tunnel syndrome. In 17 patients this was clearly demonstrated, the only exception being a boy with mucopolysaccharidosis II, age 6 months at testing. All patients had a remarkable lack of symptoms. Carpal tunnel syndrome is a very common complication of the mucopolysaccharidoses and mucolipidosis III and should be actively looked for in affected patients. Early diagnosis and treatment offer the best chance of a good response to surgery.

Resistance to ischaemic conduction failure in chronic hypoxaemia and diabetes.

Median nerve function was studied in twelve diabetic subjects, six subjects with chronic hypoxaemia and ten control subjects. Resistance to ischaemic conduction failure (RICF), a characteristic electrophysiological feature of diabetic neuropathy, was assessed by measuring the decline in median nerve action potential amplitude at minute intervals for up to 20 minutes while the arm was rendered ischaemic. Initial nerve conduction velocity and action potential amplitude was similar in all three groups. Following the onset of ischaemia the time to a 50% reduction in action potential amplitude was prolonged in both diabetic subjects and hypoxaemic subjects compared with controls. After 20 minutes of ischaemia no control subject had persisting nerve function, while function remained in 5 (80%) of hypoxaemic subjects and 10 (83%) of diabetic subjects. The time to a 50% reduction in action potential amplitude during ischaemia correlated with the blood oxygen saturation among the hypoxic subjects and haemoglobin Alc among diabetic subjects. These results are consistent with the hypothesis that hypoxia has a role in the pathogenesis of resistance to ischaemic conduction failure in diabetes.

Effect of aldose reductase inhibition on nerve conduction velocity and resistance to ischemic conduction block in experimental diabetes.

The relationships between nerve polyol levels and both nerve conduction velocity (NCV) and resistance to ischemic conduction block (RICB) in streptozocin-induced diabetic rats were examined in two studies. In the first study, sciatic NCV and RICB of the tail nerve, assessed by measuring the time to disappearance of the nerve action potential after the tail was rendered ischemic, were measured in nondiabetic rats, untreated diabetic rats, and diabetic rats given Statil, an aldose reductase inhibitor (ARI). Sciatic NCV was lower in the untreated diabetic animals than in control animals (P less than .05), and RICB of the tail nerve was greater (P less than .001). Treatment with the ARI completely prevented the slowing of NCV but had no significant effect on the increase in RICB. In the second study, similar groups of rats were treated with either ARI, insulin, or myo-inositol. Sciatic NCV was lower in the untreated diabetic rats than in the nondiabetic rats (P less than .001). In diabetic rats treated with the ARI and in those treated with insulin, NCV was greater than in the untreated diabetic rats (P less than .05 and P less than .001, respectively) and was not significantly different from the nondiabetic rats. NCV in the myo-inositol-treated rats was not significantly different from that in the untreated diabetic rats. RICB was assessed by measuring the decline in sciatic nerve action potential amplitude at minute intervals after death.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between peripheral nerve resistance to ischaemia and diabetic control.

The cause of the abnormal resistance to ischaemia of peripheral nerve function in diabetes is unknown. Median nerve function was more resistant to ischaemia in diabetic patients than in control subjects. In diabetic patients the degree of resistance to ischaemia correlated closely with HbAlc but not with the coincident blood glucose level, the duration of diabetes, the vibration perception threshold at the thumb or the initial median nerve action potential amplitude. Thus in diabetes the resistance of peripheral nerve function to ischaemia is dependent on medium term metabolic control and is not directly related to the presence or absence of neuropathy.

Pattern-reversal visual evoked potentials in patients with hydrocephalus.

Pattern-reversal visual evoked potentials (VEP's) in response to whole- and half-field stimulation were studied in 10 patients with hydrocephalus. Abnormalities consistent with optic nerve dysfunction were recorded in four patients. Two patients had response asymmetry to half-field stimulation, which suggested dysfunction of the visual pathway in the right hemisphere. The remaining four patients had normal responses. Measurement of VEP's was repeated after the surgical treatment of hydrocephalus in four patients, and showed marked improvement in two of the three patients with preoperative abnormalities. This study suggests that, in patients with hydrocephalus, VEP's are more sensitive than clinical methods in detecting visual pathway dysfunction and that they can be useful in the follow-up monitoring of surgically treated hydrocephalic patients.

Denervation in wasted hand muscles in a case of primary cerebellar ectopia without syringomyelia.

Wasting of hand muscles and electromyographic changes of denervation in a case of primary cerebellar ectopia without evidence of syringomyelia is described. It is suggested that the wasting is due to anterior horn cell damage secondary to grey matter venous obstruction at high cervical cord levels.