Neuropathy under chemotherapy.

Neuropathy is a dose-limiting side effect for a number of effective chemotherapeutic agents. A better understanding of effective mechanisms will lead to novel treatment strategies that will protect neurons without decreasing therapeutic efficacy. The assessment of the efficacy and neurotoxicity of various chemotherapeutic agents is vital, for a determination of the maximum allowable dose. The introduction of chemotherapy in the 50s and 60s of the twentieth century has resulted in the development of curative therapeutic interventions for patients with several types of solid tumours and hemopoietic neoplasms. The important obstacles encountered in the use of chemotherapy have been the toxicity to the normal tissue. During the past 8 years there has come about a new level of understanding of the mechanisms through which chemotherapeutic agents work. This has opened the door to new paradigms of treatment in which molecular, genetic, and biologic therapy can be used together to increase the sensitivity of abnormal cells to treatment, and to protect the normal tissues of the body from therapy-induced side effects. The implementation of new strategies could change the way therapy is delivered over the next few years and improve the outcome especially in patients with neoplasms that are currently resistant to conventional dose therapy.

[Variant of Klippel-Trenaunay syndrome. A case report]. / Variante eines Klippel-Trenaunay-Syndroms--ein Fallbericht.

Klippel-Trenaunay-Syndrome is a rare congenital vascular malformation with cutaneous naevi, varicose veins and limb hypertrophy. We report a patient with a variant of this syndrome presenting with extensive varicose veins and arteriovenous shunts within the left arm, bony hypotrophy of the left hand, mucocutaneous melanin spots in the face and thrombocytopenia. Imaging techniques play a major role in making a diagnosis in angiophakomatoses.

Unmyelinated fibers in human greater auricular and sural nerves: a comparative morphometric study.

Since normal structural details of human greater auricular nerve (GAN) have not as yet been studied with modern techniques, light and electron microscopic findings of seven presumably normal GANs, obtained from five patients during radical neck dissection, were compared with those of normal sural nerves (SNs). In GANs there was a tendency to higher densities per mm2 and a larger number of small-diameter fibers in myelinated fibers (MFs) and unmyelinated fibers (UFs) without obvious signs of de- or regeneration. UF histograms were unimodal in both groups, with mean UF diameters being somewhat smaller in GANS than in SNs. Schwann cell complexes containing several or even numerous UFs were more frequent in GANs than in SNs. In GANs, UF often occurred focally in great numbers within large Schwann cell complexes (polyaxonal complexes), not commonly seen in normal SNs. It is concluded that these structural peculiarities in GANs reflect natural conditions in short sensory nerves irrespective of any specific function.

Chronic multifocal neuropathy with persistent conduction block (Lewis-Sumner syndrome). A clinico-morphologic study of two further cases with review of the literature.

We present data of 2 patients suffering from chronic motor-sensory multifocal neuropathy with persistent conduction block. The first case concerns a 9-year follow-up of a female, aged 24 years at onset with persistent multiple conduction blocks and a tendency towards generalization of clinical deficits. Eight years after onset sural nerve biopsy revealed extreme interfascicular variations of de/remyelination, onion bulb formation, fiber loss, edema, and proliferation of basal lamina of endoneurial capillaries. Serum antibodies against GM1 gangliosides were not detected. The second case, a 29-year-old Yemenitic male with a 5-year history, exhibited conduction blocks in motor and sensory fibers, and a normal sural nerve biopsy. Our results are discussed with respect to those of some 30 cases individually reported in the literature.

Sural nerve biopsy findings in leprosy: a qualitative and quantitative light and electron microscope study in 4 treated cases of the lepromatous spectrum.

Reports on biopsy findings in multifascicular nerves in lepromatous leprosy (LL) are rare and detailed morphometrical data are not available. In a case of early LL with normal electrodiagnostic findings in sural nerve, the present study revealed marked segmental de- and remyelination concomitant with the sequelae of considerable Wallerian degeneration of preferentially small myelinated fibers (MF) in spite of a normal number/nerve and density/mm2. Segmental de- and remyelination of several consecutive internodes in teased fibers suggests continuous bacterial spread via Schwann cells. In 2 more advanced LL-cases, nervous parenchyme was severely reduced, in a borderline lepromatous (BL) case obviously in part caused by cell infiltrates and granulomata. Distinct fascicle differences in MF-involvement were demonstrated by coefficients of variation of MF/mm2 and teased fiber preparations in LL, consistent with the hypothesis of initial focal spread of bacteria. Numbers and densities of endoneurial vessels were increased only in the later stages of LL. Enlargement of endoneurial area, due to different factors, was encountered except for the most severe LL-case with extensive endoneurial collagenization. Morphometric results were compared with those of other neuropathies. Intact and degenerating bacteria mostly in phagosomes of Schwann cells associated with unmyelinated axons and in macrophages were seen only in the early LL- and the BL-case. Sparse mononuclear cell infiltrates and small focal necrosis, present even in LL-cases, underline the complex pathogenesis of nerve fiber involvement.

Schmidt-Lanterman clefts: a morphometric study in human sural nerve.

In the human sural nerve, large myelinated fibers contained 35 Schmidt-Lanterman (SL) clefts per mm, and small myelinated fibers contained only eight SL clefts per mm. The incidence of SL clefts is linearly related to myelin thickness. The SL clefts extended over 13 micron in large and over 9 micron in small fibers, the total extent of the SL region amounting to nearly 50% of internodal length in large and to 6% in small fibers. In the SL region, the fiber diameter was 6% larger than outside this region, and the axon was 17% smaller in large and 28% smaller in small fibers. The paranodal-nodal region occupied less than 2% of internodal length in large fibers and 6.5% in small fibers; in the nodal region the axon diameter was reduced by 40-50%.

Three dimensional analysis of Schwann cells associated with unmyelinated nerve fibres in human sural nerve.

In a cross section the profile of one or several unmyelinated axons is embraced by profiles of one or several Schwann cells, all surrounded by a basal lamina. Reconstructions demonstrate that this complex structure is the result of overlap and regrouping of contiguous Schwann cells and only to a lesser extent to branching of Schwann cells. More than half the 36 Schwann cells reconstructed did not branch within the 200 micrometer analysed, and one fourth had two branches. Notwithstanding the regrouping of Schwann cells and axons at different levels of the nerve, the number of Schwann cell subunits in a single cross section is a suitable gauge for the number of Schwann cells. The single nucleus is situated midway between the ends of the Schwann cell. The length of the Schwann cells ranges from 220 to somewhat more than 400 micrometer; the thickness is 0x2-0x5 and in the region 2-5 micrometer. Collagen pockets are outpouchings of the Schwann cell which rarely extend over more than 6 micrometer along the Schwann cell; they are spaced at average intervals of 20 micrometer. Outpounchings devoid of collagen pockets have a similar length but occur more rarely. Abnormally dense cytoplasm, when present, is seen throughout the entire length of the Schwann cell.

Sensory action potentials and biopsy of the sural nerve in neuropathy.

In 167 consecutive patients with various types of neuropathy, the amplitude of the sensory potential and the maximum conduction velocity along the sural nerve were compared with conduction in other sensory nerves, and were related to structural changes revealed by nerve biopsy. Electrophysiological findings in the sural nerve were similar to those in the superficial peroneal and the median nerve, though the distal segment of the median nerve was normal in 20 per cent of the patients when it was abnormal in the sural nerve. Quantitation of histological findings was a more sensitive method than the electrophysiological study in that two-thirds of 33 patients with normal electrophysiology in the sural nerve showed mild loss of fibres or signs of remyelination in teased fibres. The amplitude of the sensory potential was grossly related to the number of large myelinated fibres (more than 7 micrometer in diameter). Considering the 95 nerves from which teased fibres were obtained, maximum conduction velocity was abnormal in half. In 18 of these nerves, slowing in conduction was due to axonal degeneration: the velocity was as to be expected from the diameter of the largest fibres in the biopsy ("proportionate slowing"). In 9 nerves slowing was severe and more marked than to be expected from loss of the largest fibres ("disproportionate slowing"); these nerves showed paranodal or segmental demyelination in more than 30 per cent of the fibres. In 16 nerves from patients with neuropathy of different aetiology neither loss of fibres nor demyelination could explain the moderate slowing. The cause of slowing in these nerves is unknown; other conditions are referred to in which slowing in conduction cannot be attributed to morphological changes. Finally, electrophysiological and histological findings are reported in some patients with neuropathy associated with malignant neoplasm, with rheumatoid arthritis, with polyarteritis nodosa, with acute intermittent porphyria and with cirrhosis of the liver.

Histology and ultrastructure of alterations in neuropathy.

Histologic findings are described in nerves from men exposed to lead, from patients with discrete clinical signs of peripheral neuropathy, and from controls. Every nerve from control subjects showed an abnormality (paranodal remyelination, segmental remyelination, or regeneration) in teased fibers. The only histologic alteration in eight lead-exposed males without signs or symptoms of neuropathy was a slightly increased incidence of paranodal remyelination. Sixteen patients with discrete neurologic symptoms and signs had a loss of large myelinated fibers and an increased incidence of regenerated fibers among teased fibers. Electron microscopy of unmyelinated fibers showed an increased occurrence of Schwann-cell processes, of fibers undergoing degeneration, and of Schwann-cell subunits with many profiles as the earliest signs of abnormality. Clinically mild neuropathies may exhibit advanced regeneration in the case of unmyelinated fibers. The earliest sign of degeneration in myelinated fibers was a diminution in the number of axonal organelles.

Polyneuropathy. Facts and fancies.

Some conclusions are drawn from findings in 167 consecutive patients with the ordinary "garden variety" of polyneuropathy; the aetiology was unknown in 15%. Histological findings in sural nerves were related to clinical and electrophysiological abnormalities. In some patients with discrete clinical abnormalities, sensory and motor conduction and amplitudes of evoked sensory and muscle action potentials were normal, whereas the nerve biopsy showed slight but definite abnormalities. The reverse, abnormal nerve conduction and normal histological findings, did not occur. Histological findings were rarely, and electrophysiological findings were not, specific for the aetiology or type of a neuropathy. Thus, neither conduction studies nor conventional or single fibre electromyography can identify the underlying pathology: loss of large myelinated fibres (greater than 7 micrometers) was equally prominent in nerves with de- and re-myelination as in those without them. Paranodal and segmental demyelination in less than 20% of the teased fibres occurred as often in nerves with as in those without disproportionate slowing in conduction. When the recorded conduction velocity was equal to that to be expected from the fibres with the largest diameter, slowing in conduction could be explained by axonal degeneration ("proportionate" slowing, 79% of the nerves). When the recorded velocity was disproportionately slower than that expected from fibre diameter (21% of the nerves), causes other than loss of the largest fibres must be assumed to explain the slowing in conduction. Myelin abnormalities in more than 50% of the teased fibres were found only in nerves from patients with the hypertrophic type of peroneal muscular atrophy and in postgastrectomy neuropathy and can probably explain the marked disproportionate slowing in conduction. The material contained, however, only one patient with acute idiopathic polyradiculoneuropahy. In diabetic neuropathy, segmental demyelination was present in only 8 of 502 teased fibres (9 nerves), remyelination was present in 135 fibres, and could not explain the disproportionate slowing in conduction. The mechanism of disproportionate slowing, when it is not due to demyelination, is still obscure.

Nerve biopsy and conduction studies in diabetic neuropathy.

Morphological findings in sural nerves were related to nerve conduction in 12 patients with diabetic neuropathy, five with mainly sensory involvement, four with severe, symmetrical sensory-motor polyneuropathy, and three with multiple mononeuropathy. All had loss of large and small myelinated and of unmyelinated fibres, even early in the disease; segmental remyelination was the most prominent myelin alteration in teased fibres, segmental demyelination was found in only a few fibres. Axonal degeneration and Schwann cell damage seem to proceed independently of each other. The relation between recorded conduction velocity and that expected from the diameter of the largest fibres indicated that slowing of 20 to 30% was due to causes other than fibre loss; a grossly diminished conduction velocity was caused mainly by fibre loss. Electrophysiological findings in the sural nerve were largely representative of findings in other nerves, though abnormalities were less marked in the median nerve. In half the endoneurial vessels from diabetic neuropathy the perivascular space was thickened or contained more layers of basal laminae than normal. The same abnormalities were found in one-quarter of the endoneurial vessels from other acquired neuropathies.

Peroneal muscular atrophy (PMA) and related disorders. II. Histological findings in sural nerves.

Biopsy of the sural nerves distinguished two groups of patients with peroneal muscular atrophy (Charcot-Marie-Tooth): a hypertrophic type and a neuronal type. In patients with the hypertrophic type (10 nerves), 30-100 per cent of teased fibres of the sural nerve had demyelinated segments, numerous onion-bulb formations and often an increase in endoneurial space. Large and small fibres, with a diameter of more than 7 micron and less than 5 micron were diminished in number. Regeneration was scarce. There were more fibres with 60-120 myelin lamellae than in normal nerve, suggesting an atrophy of the axon. Biopsy of 19 sural nerves of patients with the neuronal type of PMA showed loss of large fibres (more than 7 micron in diameter). The number of small fibres was normal, presumably due to regeneration, since there were many "clusters" of small myelinated fibres. Fibres with demyelinated segments and onion-bulb formations were absent or rare and the endoneurial space was normal or slightly increased. Neither in the hypertrophic nor in the neuronal type did fibre loss occur selectively among the very largest fibres. Nine nerves from patients with hereditary spastic paraplegia and from a family with tremor and spasticity in addition to PMA showed changes similar in type but often milder in degree than nerves of the neuronal type of PMA. The number of unmyelinated fibres was normal in 12 of 21 nerves from patients with PMA; it was increased in 5 and diminished in 3 nerves.

Unmyelinated fibres and Schwann cells of sural nerve in neuropathy.

Electron micrographs of 45 sural nerves from patients with acquired (22) or heredodegenerative neuropathy (23) were analysed with respect to the number of unmyelinated nerve fibres, 37 nerves with respect to the number of Schwann cell sub-units and of structures connected with Schwann cells. Findings were compared with those in 6 nerves from control subjects and referred to the total number rather than to the number per mm2 to eliminate error due to increase in the transverse endoneurial area, present in more than half the diseased nerves. Ninety-one per cent of the diseased nerves showed one or several abnormalities in unmyelinated fibres of their Schwann cells. The best indicator of fibre loss was an increase in the number of Schwann cell sub-units devoid of axons, found in more than half the nerves. This was the only abnormality related with decrease in number of myelinated fibres. The increase in number of empty Schwann cell sub-units was due both to loss of unmyelinated nerve fibres and to proliferation of Schwann cells. Proliferation was indicated by the higher incidence of Schwann cell nuclei in cross-sections of diseased nerves than in controls. The earliest sign of involvement was an increase in number of profiles and of small isolated Schwann cell projections, observed in 33 of 37 diseased nerves, as the only abnormality in 7 nerves. The number of unmyelinated nerve fibres by itself was of little value to indicate loss of fibres, since regeneration often replaced or more than replaced degenerated fibres. Regeneration was indicated by an increase in number or incidence of small unmyelinated fibres, present in nearly half of 45 diseased nerves; and by an increased in the total number, present in a third of the nerves. An increase in the number of collagen pockets and of fibres undergoing degeneration (loss of organelles) and a decrease in the number of unmyelinated fibres per Schwann cell sub-units was present in only a quarter to a third of diseased nerves and was not related to other criteria of loss of fibres or of regneration.