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The peripheral neuropathy in Machado-Joseph disease.

Peripheral nerve biopsies were taken from 11 patients with Machado-Joseph disease (MJD), a heredo-degenerative disease within the group of autosomal dominant ataxias. On the basis of the clinical symptoms, 2 patients were found to suffer from type I, 4 from type II and 5 from type III. All cases shared the same pathological features, which consisted of a reduction in density of myelinated and unmyelinated fibres and an increase in endoneurial collagen. It was also observed that some Schwann cells were not related to axons, whilst others showed numerous budding processes. The intensity of the changes varied considerably: it was mild in type I and II and severe in type III. Peripheral nerve changes in MJD are compared with those previously described in other forms of heredo-ataxias. It is concluded that involvement of peripheral nerves is a significant feature in this group of diseases and that peripheral nerve biopsy could be useful in the identification of the subtypes of MJD.

Adult↗

Thrombin and its precursor in human cerebrospinal fluid.

The blood coagulation cascade proteolytic enzyme, thrombin, affects many cell types, including neurons and astrocytes, in which it prevents process outgrowth and induces significant morphological degeneration and even cell death. Since thrombin may contribute significantly to pathological conditions in the central nervous system (CNS), where it is synthesized locally, we measured the levels of thrombin and its precursor, prothrombin, in the cerebrospinal fluid (CSF) of 67 individuals from 6 groups: non-neurologic controls (NNC); spinal degenerative disease (SDD); peripheral nerve disease (PND); cerebrovascular, neuroimmune and seizure disorders and tumor (CNSD); traumatic brain injury (TBI) and neurodegenerative disorders (NDD). We employed a sensitive chromogenic assay utilizing the thrombin specific tripeptide substrate, S-2238, to evaluate CSF levels of thrombin and prothrombin. The latter estimated after its conversion to active enzyme by the snake venom prothrombinase, ecarin. No measurable active thrombin was detected in these CSF samples. However, activatable prothrombin was measured in all groups. The mean activatable prothrombin concentrations (in nM) were 7.26 +/- 3.39 (NNC); 8.85 +/- 3.09 (SDD); 6.78 +/- 2.58 (PND); 6.33 +/- 3.87 (CNSD); 5.10 +/- 1.86 (TBI), and 7.80 +/- 3.27 (NDD). Duncan's multiple comparison test showed significant reduction (p <0.05) in prothrombin levels of the TBI group. Our data suggests that the prothrombin zymogen gains access to the CSF, likely across either an intact or compromised blood-brain barrier (BBB), in increased amounts with age. Reduced levels in TBI patients may have diagnostic and/or prognostic value.

Adult↗

Imaging of peripheral nerve lesions.

PURPOSE OF REVIEW: Clinical investigations of peripheral nerve lesions routinely involve nerve conduction studies and electromyography. Imaging studies are often used to exclude focal mass lesions or external compression and to visualize muscle atrophy. More recently, it has been recognized that magnetic resonance imaging can identify changes in peripheral nerves and secondary neurogenic alterations in skeletal muscle, which may significantly enhance its use in the differential diagnosis of peripheral nerve disease. RECENT FINDINGS: Acute axonal nerve lesions cause a hyperintense signal on T2-weighted images at and distal to the lesion site, which correlates with Wallerian degeneration and nerve oedema. Superparamagnetic iron oxide particles provide an exciting new tool to detect the invasion of macrophages into the degenerating nerve distal to an axonal lesion. Prolongation of the T2 relaxation time and gadolinium enhancement of denervated muscle develop in parallel to the development of spontaneous activity on electromyography, and are probably the consequence of capillary enlargement and increased muscular blood volume. SUMMARY: Magnetic resonance imaging supplements the differential diagnosis of peripheral nerve disease. An advantage over clinical neurophysiological investigations is that it is operator independent and painless. It can identify axonal damage and may thus help to identify a lesion site precisely, where fractionated nerve conduction studies are not applicable. Novel contrast media may potentially be used to detect pathophysiologically relevant mechanisms such as infiltration of the nerve by macrophages. Magnetic resonance imaging also has the advantage of providing a lasting detailed topographical picture of regional variations and avoids localization errors of muscles in electromyography.

Humans↗

[Relationship between thermal threshold and population of peripheral nerve fibers].

The relationship skin thermal threshold (TT) and density of both myelinated and unmyelinated fibers were investigated in 12 patients with various peripheral nerve diseases including Crow-Fukase syndrome, carcinomatous neuropathy and Charcot-Marie-Tooth disease. The TT was measured at a site above the medial tibial condyle using a thermal threshold tester. The TT was defined as the threshold at which a slight rise or fall in temperature could be detected. The size of the skin stimulation area was 13.5 cm2, the temperature change rate was 1 degrees C/sec, and the basal temperature was set at 34 degrees C. A sural nerve biopsy was performed and an image processor (IBAS) was used to measure the nerve fiber density. The TT in the patients with peripheral nerve disease was found to be elevated when compared with that of the 74 healthy controls (mean age of 38.1 +/- 13.3 years). Elevation of the TT has an intimate relation to damage of the small myelinated nerve fibers. In conclusion, unmyelinated fibers may play a relatively minor role in conveying thermal sensation.

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Clinical, electrophysiological, and immunopathological study of peripheral nerves in Hansen's disease.

Hansen's disease is a disease of peripheral nerves. Some patients develop peripheral neuropathy before the diagnosis of the disease, and others develop these complications after starting therapy. Electrophysiological (EP) studies were carried out in Hansen's disease patients. This work studied the neural deficits, electromyography (EMG) and motor nerve conduction (MNC) variables in different types of leprosy and the immunopathology of sural nerve tissue in patients with severe neural deficits. Forty leprosy patients had neurological examinations and EP study. Histopathological and immunopathological study of sural nerve biopsy specimens was performed for 10 patients with severe neural deficits. The results of the neurological study showed that there was involvement of cranial nerves, muscular system, motor reflexes and sensory system and trophic and vasomotor changes. EP study showed significant changes in EMG of abductor digiti minimi in patients as compared to controls. MNC variables of common peroneal nerve were abnormal in 80% of all patients, MNC of median nerve was abnormal in 72.5%, while MNC of ulnar nerve was abnormal in 70% and SNC of ulnar nerve was abnormal in 77.5% of the total. In conclusion, electrophysiological investigations have an important role in the detection of muscle denervation and neuropathic changes in leprosy patients. These investigations are safe, rapid and non-invasive techniques. On the other hand immunopathological study revealed that the degree of immune positivity correlated with the degree of nerve fibrosis.

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