Pseudohypertrophic myopathy in cysticerosis.

A patient with diffuse involvement of the central nervous system and pseudohypertrophic muscular changes induced by cysticerci is described. Electromyographic and pathologic changes are reported for the first time. Electromyographic examination demonstrated numerous short-duration, low-amplitude motor unit potentials in proximal muscles. Biopsy showed swelling of muscle fibers, fiber atrophy with fibrosis, and cellular infiltration separate from inflammatory exudate surrounding numerous cysts.

Pathology and time relationship of peripheral nerve changes in experimental diabetes.

Structural changes have been studied in peripheral nerves in streptozotocin-induced diabetic monkeys. Teased single nerve fibre preparations were most informative. Abnormalities were present in 32 of 58 nerves examined from 15 diabetic monkeys with varying degree of hyperglycaemia. The earliest change was an increase in the gap at nodes of Ranvier, seen 12 weeks after the diabetic state had been established. Well marked segmental demyelination was seen in distal nerves at 14-16 weeks. Later similar changes were seen in proximal, larger nerves. Evidence of remyelination was present at a later date. Wallerian degneration was seen in only 4 nerves. Changes in the myelin sheath were more prominant than axonal abnormalities at all times. There was no abnormality in the vasa nervorum and only a mild increase in endoneurial and perineurial fibrous tissue. A direct correlation was present between the extent and degree of pathology and both severity as well as duration of hyperglycaemia.

Role of porta systemic shunt and hepatocellular damage in the genesis of hepatic neuropathy.

A study was undertaken to evaluate the relative role of porta-systemic shunts and hepatocellular damage in the genesis of neuropathy in chronic liver disease. Two of the 14 patients with non-alcoholic cirrhosis showed clinical evidence of neuropathy, whereas none of the patients with idiopathic portal fibrosis had evidence of neuropathy clinically. Decreased motor conduction velocities were present in some cases of idiopathic portal fibrosis as well as non-alcoholic cirrhosis. Subclinical evidence of histopathological neuropathy in the form of segmental demyelination and remyelination as well as myelin fiber loss was seen in 10 out of 11 sural nerves studied in idiopathic portal fibrosis group and in all the 10 patients in the non-alcoholic cirrhosis group. No correlation was found between histological features and various parameters studied. It is postulated that the development of clinical or subclinical neuropathy in chronic liver disease depends on two factors, being collateral shunting and hepatocellular damage or both and probably related to abnormalities of nitrogen metabolism.

Pseudorandom binary sequence stimulation applied to the visual evoked response. Normative data and a comparative study with pattern and flash stimulation.

The investigation of patients who are unable to fixate the pattern visual stimulus generally requires the use of diffuse flash stimulation to elicit the visual evoked response. However, by comparison with pattern, flash stimulation has proved relatively insensitive in identifying lesions of the visual pathway. We investigated a more complex method of flash stimulation. A pseudorandom binary sequence has been used to generate the diffuse visual evoked response stimulus. The pseudorandom binary sequence, rather than producing a single flash, switches in a pseudorandom fashion between two levels of illumination. The result is a diffuse visual stimulus approximating band-limited white noise. The series is periodic, enabling signal averaging to be performed. By applying the methods of random signal analysis, the impulse or transient response of the visual pathway can be determined. Our normal pseudo-random binary sequence visual evoked response impulse function, derived from 29 normal subjects, had the morphologic characteristics of the conventional flash visual evoked response and a major positive component (P100), whose latency mean and standard deviation closely matched that of our normative pattern visual evoked response. However, the P100 amplitude standard deviation was significantly greater than that produced by conventional pattern and flash stimulation. We investigated 140 patients by means of pattern, flash and pseudorandom binary sequence stimulation. The pseudorandom binary sequence visual evoked response proved to be almost 12 times more effective than flash visual evoked response in detecting lesions of the visual system.