Lower motor and primary sensory neuron diseases with peroneal muscular atrophy. II. Neurologic, genetic, and electrophysiologic findings in various neuronal degenerations

Peroneal muscular atrophy. Part 1. Clinical and electrophysiological study

144 patients with the clinical syndrome of peroneal muscular atrophy or Charcot-Marie-Tooth disease were studied. Thirteen were recognized as the spinal form of the disease since all had normal motor nerve conduction velocity and sensory nerve action potential. The remaining patients could be classified according to their values of motor conduction velocity for the median nerve. Two main groups were therefore identified: 55 patients whose nerve conduction was below 30 m/s belonged to group I, which corresponds to the previously reported hypertrophic form or hereditary motor sensory neuropathy (HMSN) type I. Sixty-four patients whose nerve conduction was above 40 m/s belonged to group II which corresponds in the majority of cases to the neuronal form or HMSN type II. Twelve patients could not be classified since the motor nerve conduction velocity for median nerve ranged between 30 and 40 m/s. These could belong to either of the two main groups or might form an intermediate group, the existence of which is discussed. Clinical genetic and electrophysiological features of the two main groups are discussed and compared.

Dominantly inherited motor and sensory neuropathy type I. Genetic, clinical, electrophysiological and pathological features in four families

This report describes the genetic, clinical, electrophysiological and sural nerve biopsy features in 26 affected members and 21 unaffected relatives from 4 families with autosomal dominant inherited motor and sensory neuropathy (HMSN), Type I. In all age categories, the proportion of affected to unaffected individuals at risk did not significantly differ from the expected 50%. The peak age of onset was in the first decade. There was a complete concordance between nerve conduction velocity in the propositi and that in their affected relatives within each family. Marked slowing of conduction velocities was present as early as the age of 2.5 years, while precocious clinical signs and symptoms were quite subtle. Determination of conduction velocity is a valuable aid aid to the early diagnosis of the disease.

Peroneal muscular atrophy. Part 2. Nerve biopsy studies

The present study used the nerve pathology, studied by quantitative light microscopy, as the sole basis for classification of peroneal muscular atrophy (PMA). The findings in biopsies of superficial peroneal nerves of 20 patients were compared with normal values obtained from 8 controls. Three homogeneous groups comprising 17 out of 20 patients were clearly identified. The hypertrophic type (7 cases) was characterized by (1) many multilamellated onion bulb formations; (2) extensive loss of MF with both involvement of the largest and smallest fibers; (3) lack of significant cluster formation. The neuronal sensori-motor type (5 cases) was characterized by (1) absence of any OB; (2) elective loss of large MF; (3) abundance of clusters with significant increase of the small MF population. The neuronal motor type (5 cases) showed a virtually normal sensory nerve except for fairly numerous clusters in some cases. Comparing this classification based on histomorphometric grounds, with the electrophysiological data it appears that 14 patients out of 17 would be correctly classified as hypertrophic or neuronal with respect to the motor nerve conduction velocity of the median nerve alone. Three cases were not classified in the previous groups since they differed notably in one or more parameters from the typical cases. A possible intermediate group is discussed.

Peripheral and central sensory nerve conduction in Charcot-Marie-Tooth disease and comparison with Friedreich's ataxia

Somatosensory evoked potentials were recorded in response to stimulation of the median nerve at the wrist and the elbow in 14 cases of Charcot-Marie-Tooth disease (CMTD). Cervical and cortical latencies were used to derive conduction times and velocities over peripheral and central segments of the pathway. Sensory conduction velocities between the wrist and the elbow were distributed bimodally (12-27 m/s and 36-70 m/s), but did not correspond with the bimodality of motor conduction velocity values in 4 cases. Three patients had severely slowed sensory conduction in one arm but only moderate slowing in the other. In the majority of cases sensory conduction was considerably faster from the elbow to the spinal cord than from the wrist to the elbow. This was most apparent in 2 young patients, suggesting that demyelination secondary to axonal degeneration may gradually progress from distal to proximal segments. Compared with a group of Friedreich's ataxia (FA) patients, almost all CMTD cases could be distinguished by a greater degree of peripheral conduction slowing (not significant in FA). In FA there was a much higher incidence of impaired conduction over central segments of the somatosensory pathway, although evidence of this was also seen in 5 CMTD cases. Three of the latter had presented with atypical symptoms suggestive of CNS involvement, and also had delayed visual evoked potentials.

Hereditary motor and sensory neuropathies in Swedish children. II. Neuronal-axonal types

Clinical, neurophysiological and laboratory data are given for 32 children (30 kinships) considered to represent hereditary motor and sensory neurophaties (HMSN) of neuronal-axonal types. In 25 families (27 cases) one of the parents was found to be affected. In one both parents were normal. The mode of inheritance in the 27 patients with familial neuronal-axonal HMSN was concluded to be autosomal dominant HMSN II (Lambert type). The disability was mild to moderate and, on an average, less pronounced than in de- and remyelinating types of HMSN. Seven out of 27 were early toe-walkers of the secondary type. Cavus feet were noted in 25, hand atrophies in eight and mild scoliosis in five. Sensory complaints were recorded in 21. The nerve conduction velocities (NCVm and NCVs) of children and parents were slightly subnormal in a few. EMG proved to be the most important parameter for identifying subclinically affected parents.

First report of mosaic trisomy 12 in a liveborn individual

Trisomy 12 mosaicism was found in a 36-year-old woman with minor anomalies, neuromuscular abnormalities, and moderate mental retardation. Trisomy 12 was present in 13% of the lymphocytes but not in skin fibroblasts. Previous reports of dup (12p) and dup(12q) are reviewed. To our knowledge this is the first report of a "complete" trisomy 12 in a liveborn individual.

The nosology of genetic peripheral neuropathies in Swedish children

103 consecutive childhood cases of genetic peripheral neuropathies of heredodegenerative background were collected from Gothenburg from 1973 to 1980. From this series, 63 hereditary motor and sensory neuropathies (HMSN) were distinguished: 31 cases of demyelinating and remyelinating HMSN (HMSN I), 21 (18 families) with an autosomal dominant and 10 with sporadic mode of inheritance and unaffected parents; and 32 cases of neuronal-axonal types (HMSN II), 27 of whom (25 families) had at least one affected, if asymptomatic, parent. In one family, both parents were neurologically and neurophysiologically completely normal. Three cases of uncharacteristic HSN were diagnosed. Among 37 cases with a combined degenerative encephalopathy/myelopathy and a peripheral neuropathy, nine had hereditary spastic paraplegia, six had heredoataxias (three of the Friedreich type), nine had lysosomal storage diseases (five of the Krabbe type), seven had other known inborn metabolic errors and six had biochemically undefined disorders. Progressive neuropathies are important manifestations of a large variety of genetically determined heredodegenerative neurological disorders of infancy and childhood. For classification of HMSN, clinical and neurophysiological examinations are necessary for the index case and for both parents as well.

Hereditary motor sensory neuropathies in childhood

Clinical data on 24 patients with hereditary motor sensory neuropathies, with onset in the paediatric period, and of their relatives, is reported. Electrophysiological studies were done in all patients and in 15 relatives. The patients were divided into two groups (Types I and II) and their hereditary trait was determined. In 11 patients a sural nerve biopsy was performed and revealed different patterns of histological alterations. The nerve biopsy always confirmed the value of conduction velocity in distinguishing between Types I and II. A genetic discordance was observed, both in regard to the phenotype and the conduction velocity, and there was increased slowing of the conduction velocity as individuals grew older. Thus the classification of these disorders in childhood can be particularly difficult. The rôle of sural nerve biopsy is discussed.

A clinico-pathological study of chronic hereditary motor neuropathy

Forty cases of chronic hereditary motor neuropathy (CHMN) were divided into five categories according to the distribution of muscle atrophy; they were proximal, facioscapulohumeral, bulbospinal, distal and scapuloperoneal forms. Their clinical features and laboratory data were analysed, and muscle biopsies from 32 of them were studied by histological, histochemical and electron microscopical methods. An attempt at quantitative assessment of the histological changes was also made. All muscle biopsies showed a mixture of neurogenic and 'myopathic' changes in varying proportions. They showed more 'myopathic' changes than Werdnig-Hoffmann's disease, amyotrophic lateral sclerosis and other neurogenic atrophies except Charcot-Marie-Tooth disease. There was marked variation in the average number of atrophied muscle fibers contained in grouped atrophy. Frequently, deranged internal structure of the muscle fibres was revealed both by histochemical and electron microscopical methods. Based on the evidence of heterogeneity of CHMN in respect of genetics, clinical features and histological changes, it was speculated that CHMN represents a group of diseases which involves primarily different parts of the motor units.

Friedreich's ataxia: electrophysiological and histological findings

Electromyography was performed, and motor and sensory nerve conduction velocities were measured in 19 patients definitely affected by Friedreich's ataxia. Biopsy of the sural nerve was also performed in 9 patients. Most patients presented a moderate to severe loss of motor units, a significant increase in mean duration of motor unit potentials, and in the incidence of polyphasic potentials. Short-lasting spontaneous activity was rarely seen. Conduction velocity along the motor and sensory fibres of the median and tibial nerves was moderately slowed, while distal conduction time to muscle was significantly increased and the sensory orthodromically-evoked response markedly reduced. Intraoperative electrophysiological recordings obtained during biopsy of the sural nerve in 4 patients were consistent with the changes conventionally observed in the median, tibial and sural (6 patients) nerves. Quantitative histology revealed a reduced number of total myelinated fibres with a severe loss of large fibres, and a moderate loss of fibres of less than 7 microns in diameter. In teased nerve fibre preparations, the most evident abnormality consisted of fibres with uniformly short internodal length, while signs of remyelination were less prominent. Signs of active axonal degeneration were rarely observed in electron microscopy. Electrophysiological and histological findings were uniformly distributed, and the changes were neither related to the duration nor to the severity of the clinical condition.

Quantitative electromyography in babies and young children with primary muscle disease and neurogenic lesions

The technique of quantitative electromyography suitable for babies and young children is reviewed. The findings in 22 children with myopathic disease and 21 with neurogenic disease have been compared with the results from 25 children with no evidence of neuromuscular disease (the Apparent control group). Children with primary muscle disease had low Mean Ratios of mean amplitude/turns per second whereas those with neurogenic lesions had high Mean Ratios. The most abnormal results were found in children with muscular dystrophies and anterior horn cell disease.

Linkage of autosomal dominant type I hereditary motor and sensory neuropathy to the Duffy locus on chromosome 1

Data from English families confirms the probable linkage of the loci for autosomal dominant type I hereditary motor and sensory neuropathy (HMSN) and the Duffy blood group. The locus for autosomal dominant type I HMSN is in chromosome 1 near the centromere, about 15 centimorgans from the Duffy locus. The linkage between type I HMSN and the Duffy locus and the two recombinants found between Duffy and type II HMSN support the hypothesis that there are at least two genetic variants of autosomal dominant HMSN.

Electrophysiological investigation of the auditory system in Friedreich's ataxia

Auditory brainstem responses (ABRs) and cortical auditory evoked responses (AERs) were studied in a series of 16 Friedreich's ataxia patients who varied in age, degree of clinical involvement and duration of the disorder. The ABRs were markedly abnormal in all but the youngest patient, and the abnormalities reflected the severity and duration of the disease. The latencies of the AERs were significantly longer in the Friedreich's ataxia patients compared to normal controls, suggesting cortical as well as peripheral involvement of the auditory system. These data are discussed in terms of the neuropathology of the disorder and the similarities with the other sensory systems in Friedreich's ataxia patients.

A case of Charcot-Marie-Tooth disease mimicking Friedreich's ataxia: is there any association between friedreich's ataxia and Charcot-Marie-Tooth disease?

The authors report a case of Charcot-Marie-Tooth disease that mimicked Friedreich's ataxia and featured impaired tendon reflexes in the limbs, incoordination mimicking cerebellar disease in the extremities, extensor plantar responses on both sides, bilateral foot deformity, imparied position sense in the toes, absent vibratory sense in the distal parts of the legs and minimal distal weakness with wasting. Motor conduction velocity in the upper limbs was substantially reduced. Other cases similar in nature reported in the literature resemble spino-cerebellar degeneration in general, and Friedreich's ataxia, in particular. It is emphasized that the natural history, EMG, motor conduction velocity studies and examination of other affected members of the family permit the correct diagnosis to be made in such cases. It is also emphasized that patients similar to the one reported here may also resemble, and should be differentiated from, cases of familial dorsal column ataxia (Biemond type). Stress is put upon the fact that when Charcot-Marie-Tooth disease mimicks spino-cerebellar degeneration, substantial slowing of motor conduction in the upper limbs is generally sufficient to establish the diagnosis. The relation between Friedreich's ataxia an Charcot-Marie-Tooth disease is reviewed and it is concluded that these two disorders are distinct clinical and pathological entities.

A family study of Charcot-Marie-Tooth disease

Forty-seven cases of Charcot-Marie-Tooth peripheral neuropathy were seen in 18 families within a defined area, with a disease prevalence of 1 in 16 400. Maximum motor nerve conduction velocity (MNCV) measurement divided off two types of neuropathy (MNCV less than 30 ms-1 and greater than 40 ms-1), but did not distinguish clinically affected from normal in families whose probands had median nerve MNCV greater than 40 ms-1. In the neuronal type of neuropathy ((MNCV greater than 40 ms-1) two genotypes were seen, autosomal dominant (ADN) and autosomal recessive (ARN). Most cases with the demyelinating type (MNCV less than 30 ms-1) had an autosomal dominant genotype (ADD) but one family had possible X linked recessive inheritance (XRD). In one autosomal dominant family a father and son had different electrophysiological types of neuropathy. Peroneal muscle weakness was progressive with age in the ADD genotype and certain patterns of phenotypic features were associated with the major genotypes. Age of onset was not found to be reliable in distinguishing genotypes. Care is needed when counselling isolated male cases because of asymptomatic affected females in the autosomal dominant genotypes, and the possibility of ill defined X linked forms.

H-reflex studies in a family with possibly X-linked neuronal Charcot-Marie-Tooth disease

The neuronal type of Charcot-Marie-Tooth disease (hereditary motor and sensory neuropathy, type II) was found to be present in ten of thirty-two members of one family. Motor nerve conduction velocities in this type of the disease may be normal in persons who are only mildly affected. Hoffmann-reflex investigation was effective in discriminating between affected and non-affected subjects. The mode of inheritance seemed to be X-linked, but this remained doubtful, because the outcome of the Hoffmann-reflex investigations was abnormal in one clinically non-affected boy. Xg(a)-typing gave no information as to linkage with the gene-locus of CMT. Close linkage between the loci for deutan anomaly and for CMT appeared to be very unlikely.

Hereditary "pure" spastic paraplegia: a clinical and genetic study of 22 families

In 22 families with the "pure" form of hereditary spastic paraplegia inheritance was autosomal dominant in 19 and autosomal recessive in three. Examination of intrafamilial correlation of age of onset in the dominant cases suggested that the disorder is genetically heterogeneous. Two forms of dominant hereditary spastic paraplegia were identified: one with an age of onset mostly below 35 years (type I), and the other onset usually over 35 years (type II). In the type I cases, delay in walking was not infrequent and spasticity of the lower limbs was more marked than weakness. The disorder was very slowly progressive and was extremely variable in terms of severity. Sixteen per cent of the patients aged over 20 years were asymptomatic but clinically affected. In the type II group muscle weakness, urinary symptoms and sensory loss were more marked. This form of the disease evolved more rapidly. In the three families demonstrating autosomal recessive inheritance the clinical features were very similar to those of the dominant cases. Biological fitness of patients from both the dominant groups was not impaired and no definite evidence of new mutation was observed. A cumulative frequency curve of age of onset in the type I group was constructed with suggested that an asymptomatic child of an affected parent has a 20% chance of developing the disease at the age of 25 years; the risk is probably even less if the child is clinically normal.

Intensive evaluation of referred unclassified neuropathies yields improved diagnosis

Intensive evaluation of 205 cases of undiagnosed neuropathy in a center with special approaches and facilities permitted classification of 76% of the patients. Inherited disorders accounted for 42% of the series, 21% of the patients were shown to have inflammatory-demyelinating polyradiculoneuropathy, and 13% had neuropathies associated with other disorders. A considerable improvement in diagnosis was possible from evaluation of the kin of the patients with undiagnosed neuropathy. Analysis of the frequency and type of various sensory symptoms also was helpful in distinguishing between acquired and inherited neuropathies.

Hereditary motor and sensory neuropathy of neuronal type with onset in early childhood

Eleven cases of a severe neuropathy with onset in early childhood are described. The condition commences with distal weakness and wasting of the lower limbs and subsequently involves the hands, causing severe paralysis of the hands and feet towards the end of the second decade. Sensory changes are common but are usually only mild. The peripheral nerves are not enlarged. Claw hand, scoliosis and other orthopaedic deformities are seen in the later stages. CSF protein is not elevated and there is only mild slowing of motor conduction velocities. The pathological changes in sural nerve biopsies are those of axonal degeneration affecting myelinated and unmyelinated fibres. Family studies suggested autosomal recessive inheritance in two kindreds and dominant inheritance in another. Five cases were sporadic. The condition is clinically more severe and of earlier onset than hereditary motor and sensory neuropathy (HMSN) type II and differs electrophysiologically and pathologically from Déjerine-Sottas disease.

[Peroneal atrophy in Tunisia. Study of 70 cases, pure or associated with other heredodegenerative diseases]

Seventy cases of hereditary peripheral neuropathy of Charcot-Marie-Tooth type have been studied. One group of 40 cases from 30 families had a pure peripheral neuropathy, the other 30 from 20 families having other associated inherited nervous defects. The classification of Dyck and Lambert (1968) modified by Dyck (1975) was used, but it proved difficult to distinguish pure types and transitional forms were common. Histological criteria appeared more reliable than clinical features and were the most constant finding within a given family. In forms associated with other abnormalities a hypertrophic and a neuronal form could be distinguished but similar difficulties in classification were encountered as the mode of genetic transmission, age of onset, clinical features and nerve conduction velocity were comparable in the two groups. Discrepancies between electrophysiological and histological findings may result from examining motor nerves with the former technique and sensory with the latter. Despite subdivision there is still a sharp distinction between the various forms of Charcot-Marie-Tooth disease and the hypertrophic neuropathy of Déjerine-Sottas. The genetic pattern is complicated by the frequent association with other inherited abnormalities.

Early onset cerebellar ataxia with retained tendon reflexes: a clinical and genetic study of a disorder distinct from Friedreich's ataxia

Twenty patients are described with a distinctive clinical syndrome characterised by progressive cerebellar ataxia developing within the first two decades. This is associated with dysarthria, pyramidal signs in the limbs, normal or increased knee jerks and upper limb reflexes and in some instances sensory loss. Inheritance is probably autosomal recessive in the majority, if not all, of the cases. The preservation of tendon reflexes distinguishes this disorder from Friedreich's ataxia. Other important differences from Friedreich's ataxia are absence of optic atrophy, cardiomyopathy, diabetes mellitus and severe skeletal deformity. The prognosis was better in the present series than in cases of Friedreich's ataxia; patients remained ambulant, on average, for more than 10 years longer.

Peripheral neuropathy in spinocerebellar degenerations

Nerve conduction studies have been performed in 19 subject with hereditary spinocerebellar degenerations other than Friedreich ataxia. Clinically, they may be classified as olivopontocerebellar atrophy or cerebello-olivary degeneration. In 9 patients, sensory conduction was abnormal, and in the whole group there was a significant impairment of sensory conduction and mild slowing of motor conduction in the lateral popliteal nerve. Sural nerve biopsies were performed on 5 patients. In 3 cases there was a mild to moderate reduction of myelinated fibers of all diameters; unmyelinated fibers were normal. In 1 patient from a kindred with a spinocerebellar degeneration in which the inheritance was autosomal dominant, neuropathological findings at autopsy confirmed the clinical diagnosis of the Menzel type of olivopontocerebellar atrophy; there was a degeneration of dorsal root ganglion and anterior horn cells as well as of myelinated fibers of all diameters in the sural nerve.

Dominantly inherited peroneal muscular atrophy (hereditary motor and sensory neuropathy type I) in infancy and childhood

A detailed clinical and electrodiagnostic study has been undertaken of demyelinating polyneuropathy in 14 children (9 male, 5 female) from 11 sibships and their parents. The onset of symptoms was before the age of 2 years in 12 of the 14 children, and the condition in all cases was nonprogressive or very slowly progressive. In each case one of the parents had a slow motor nerve conduction velocity. Five of the 11 affected parents were completely asymptomatic. Electrodiagnostic studies in both parents of all children with demyelinating peripheral neuropathy are thus important to identify the dominantly inherited form of the disease.

Friedreich's ataxia in northern Italy: I. Clinical, neurophysiological and in vivo biochemical studies

Eighteen patients with the presumptive diagnosis of Friedreich's ataxia were studied. Clinical, neurophysiological and biochemical data were concordant in 14 patients and led to the diagnosis of typical Friedreich's ataxia in this group of patients. The remaining 4 patients differed from the typical patients in several respects, but mainly in the cardiological findings. It is concluded that no single clinical or laboratory finding is typical of F.A. Multidisciplinary approaches are essential to the diagnosis of Friedreich's ataxia.

Friedreich's ataxia. I. Clinical, neurophysiological and in vivo biochemical studies

Eighteen patients with the presumptive diagnosis of Friedreich's ataxia were studied. Clinical, neurophysiological and biochemical data were concordant in 14 patients and led to the diagnosis of typical Friedreich's ataxia in this group of patients: the remaining 4 patients differed from the typical patients in several respects but mainly in the cardiological findings. It is concluded that so far no single clinical or laboratory finding is typical of F.A.. Multidisciplinary approaches are essential to the diagnosis of Friedreich's ataxia.

Genetic aspects of hereditary motor and sensory neuropathy (types I and II)

The genetic features of a series of 227 patients with hereditary motor and sensory neuropathy (HMSN) have been analysed. The series comprised 119 index cases from 110 families in which 108 affected relatives were identified. The cases were classified as having type I or type II HMSN on the basis of nerve conduction studies. Inheritance in the type I cases was autosomal dominant in 139 (45 families) and autosomal recessive in eight (four families) with 26 single cases. For the type II cases, 35 (17 families) were autosomal dominant and three (two families) autosomal recessive with 16 single cases. A significant excess of males was present in the combined single and recessive type I cases and in the type I index cases. No X linked pedigrees were identified.

The correlation coefficients for motor nerve conduction velocity between the index cases and their relatives suggested further genetic heterogeneity in the type I cases. Parent-offspring and sib-sib correlation coefficients for age of onset in the dominantly inherited type I cases were less than 0·5. There was therefore no strong suggestion of genetic heterogeneity in terms of age of onset.

The severity of muscle weakness did not differ between the dominantly inherited type I and type II cases. In both types males had higher weakness scores than females, but there was no difference for either type in relation to the sex of the affected parent.

Segration analysis suggested that approximately 70% of the single generation type I cases were of autosomal recessive inheritance, whereas only about 25% of the single generation type II cases were recessive. Biological fitness was reduced in type II HMSN, which would support a higher proportion of new dominant mutations among the single cases of this type than in type I. Despite the excess of males in the type I single case/recessive category, a contribution of cases with X linked recessive inheritance is improbable. Single cases of HMSN, especially the type II form in view of its later onset, are likely to be unrecognised clinically and will be classified as `cryptogenic' neuropathy. As in many affected subjects the degree of disability is minimal, a careful scrutiny of the relatives is merited in such instances.

Pattern shift visual evoked potentials in Charcot-Marie-Tooth disease, HMSN type I

Pattern shift visual evoked potentials were investigated in 9 subjects with Charcot-Marie-Tooth disease, who were classified as HMSN I on clinical, genetic and electromyographic criteria. The latency of the second positive peak was increased in 7 eyes of 5 subjects. These results suggest that patients with HMSN I the optic nerves may be affected more frequently than suspected on clinical examinations.

Sex-linked recessive inheritance in Charcot-Marie-tooth disease with partial clinical manifestations in female carriers

A large kindred with sex-linked recessive inheritance of Charcot-Marie-Tooth disease is presented. Partial clinical manifestations without functional disability and decreased nerve conduction velocity was demonstrated in the female heterozygotes.

Distal and scapuloperoneal distributions of muscle involvement occurring within a family with type I hereditary motor and sensory neuropathy

Davidenokow's syndrome has been defined as a hereditary disorder characterized by proximal muscle weakness and wasting in the uper limbs with distal weakness in the lower, and associated with distal sensory loss in all four limbs. It has been assumed to be genetically distinct. A family is described in which the index case displayed these features. Motor nerve conduction velocity was substantially reduced. Another member displayed distal motor and sensory involvement in both upper and lower limbs and thus conformed to the clinical pattern of the hypertrophic form of Charcot-Marie-Tooth disease (hereditary motor and sensory neuropathy type I). A third member was somewhat intermediate, with generalized upper limb and distal lower limb weakness. It is concluded that Davidenkow's syndrome is not genetically distinct and that it may occur as a phenotypic manifestation of type I hereditary motor and sensory neuropathy.

Autosomal recessive forms of hereditary motor and sensory neuropathy

Six families are described with hereditary motor and sensory neuropathy (HMSN) of probable autosomal recessive inheritance. Four of these were classified as HMSN type I and two as type II. The consanguinity rate in this series was high, suggesting that these recessive genes are rare. In comparison with the dominantly inherited forms of these disorders, the mean age of onset was significantly earlier for the type II cases but did not differ for the type I patients. Motor nerve conduction velocity was significantly less for the type I cases but did not differ for the type II form. The recessive type I cases tended to show a greater incidence of weakness, ataxia, tendon areflexia and scoliosis than in the dominant form. The importance of differentiating such cases from Friedreich's ataxia is emphasised.

[Investigations of peripheral and central somatosensory pathways in peroneal muscular atrophy and Friedreich's heredoataxia (author's transl)]

Twenty-eight patients with peroneal muscular atrophy (PMA) have been investigated. Eighteen of them were affected by the Charcot-Marie-Tooth disease and three by Dejerine-Sottas disease. In these 21 cases the nerve conduction velocity (NCV) was decreased. Four patients presented the neuronal type of PMA, two cases showed sensory neuropathy of the neuronal type with ophthalmoplegia, and one case, PMA with ataxia, i.e., a myatrophic ataxia. In the neuronal type of PMA, including both cases with ophthalmophegia, the amplitudes of the sensory nerve action potentials were decreased, and the NCV was normal to slightly subnormal. In myatrophic ataxia NCV was decreased. In all cases with reduced NCV, the latencies of the spinal-evoked potentials (spinEP) and somatosensory-evoked potentials (ssEP) were prolonged. In the neuronal type of PMA, these latencies were normal. The central latencies (from thoracic and cervical level) were normal in all 28 patients with PMA of different types. Seventeen patients with Friedreich's heredoatazia have been investigated. In all except two cases, NCV was normal. The sensory nerve-action potentials markedly decreased or disappeared in all cases. The peripheral neurographic picture, accordingly, corresponds to that of patients with the neuronal type of PMA. The latencies of spinEP were normal. All patients with Friedreich's heredoatazia, however, showed prolonged latencies of ssEP. Calculating the central latencies as the difference between ssEP and spinEP latencies (cervical and thoracic) confirms that this is due to a slowing of the conduction velocity via the spinobulbar tracts.

Hereditary distal spinal muscular atrophy with vocal cord paralysis

A large kindred is described in which an unusual form of spinal muscular atrophy is segregating in an autosomal dominant manner. The disease presents most commonly in the teens with small muscle wasting in the hands, particularly involving median nerve musculature. Subsequently distal muscle wasting and weakness occur in the lower limbs. Vocal cord paralysis is a characteristic and potentially hazardous feature. No previous report of this condition has been found.

Classification of spinal muscular atrophies

Clinical heterogeneity within the spinal muscular atrophies (SMA) has long been a source of confusion for questions of prognosis and genetic counselling. Comprehensive clinical and genetic analyses of 240 consecutive index cases from two English centres (The English SMA Study) have enabled some nosological questions to be resolved. The different SMA syndromes can be discriminated by (a) age at the first clinical signs of the disease, (b) pattern of muscle involvement, (c) age at death of other patients within an affected kindred, and (d) genetic evidence. Seven different SMA syndromes can be defined clinically and genetically; thirteen mutant genes are incriminated. Prevalence and incidence figures are presented. SMA type I (Werdnig-Hoffman disease) and chronic childhood SMA together comprise 74% of all SMA cases. The classification of the spinal muscular atrophies presented also provides the differential diagnosis for newly presenting cases.

Abnormal vascular reflexes in Charcot-Marie-Tooth disease

Vascular reflexes were assessed in 17 adult patients with Charcot-Marie-Tooth disease using the Valsalva manoeuvre, and the pulse rate and systolic blood pressure responses to standing. Six patients showed abnormalities consistent with an autonomic neuropathy. One patient had giant nerve fibre bundles in the myenteric plexus of bowel resected for co-existent Crohn's disease, indicating histological involvement of these autonomic neurones. Other evidence of an autonomic component to the peripheral neuropathy of Charcot-Marie-Tooth disease is reviewed.

Hereditary distal spinal muscular atrophy. A report on 34 cases and a review of the literature

A description is given of 34 patients with the distal form of hereditary spinal muscular atrophy. This disorder constitutes one form of "peroneal muscular atrophy". It resembles types I and II hereditary motor and sensory neuropathy but differs from them in displaying less upper limb weakness, relative preservation of the tendon reflexes and an entirely normal clinical sensory examination. Motor nerve conduction velocity and sensory nerve action potentials are normal. Previous reports of this disorder are reviewed and compared with the present series.

Distal spinal muscular atrophy. A clinical and genetic study of 8 kindreds

Twelve patients (8 kindreds) with distal SMA are described, and an analysis presented of their clinical and genetic features. Distal SMA accounted for 10% of all patients with SMA in a total population survey of this disease in North-East England. The parental consanguinity rate is high, occurring in 3 of the 8 kindreds reported; the sex ratio was 1.0; the segregation ratio of sibs did not differ from 0.25. Intrafamilial concordance for clinical features of the disease is high. This current data is consistent with a suggested aetiology of two separate autosomal recessive genes. Clinical features are discussed and a review of the literature presented. The disease is only slowly progressive, but one of the genetic types may present with infantile or early juvenile onset; there is no evidence that it shortens life. 50% of cases did not have a normal gait after 4 years of age; 50% could not run after 17 years of age; and 50% could not walk unaided after 28 years of age. Details of prognosis, and principles of genetic counselling in this disease are discussed.

[Familial spastic paraplegia with amyotrophy. Clinical, electromyographic, histochemical study and microdissection]

Four cases of familial spastic paraplegia with amyotrophy in siblings from a consanguineous married are reported. The routine laboratory examination were normal. The electromiography and muscle biopsy processed by histochemistry showed signs of denervation with reinervation. The motor nerve conduction velocity was decreased in the peroneal nerve in 3 cases. The teased fiber preparation of sural nerves was abnormal in four cases. It was found increased of C, D and G fibers suggesting demyelination with secondary remyelination. The authors believe the abnormalities found could be due the distal axonal degeneration, with secondary regeneration and suggest the hypothesis that the fact is an axoplasmic flow defect in the central and peripheral nervous system.

Bilateral abductor vocal cord paralysis in Charcot-Marie-Tooth disease

This report descirbes the unusual association of bilateral abductor vocal cord paralysis (BAbVCP) and Charcot-Marie-Tooth disease in a boy and his natural mother who have been followed for eight years. The boy initially presented with life-threatening respiratory distress at age ten years; BAbVCP was documented by direct laryngoscopy. Mirror laryngoscopy confirmed BAbVCP in the mother. Neurological diagnosis was made by history, physical examination, electromyography, and nerve conduction velocity studies. The BAbVCP may represent an additional genetic marker within the spectrum of heredodegenerative disorders. Of clinical importance is examination of voice and respiratory symptomatology of patients with heredodegenerative diseases and neurological work-up of patients with familial vocal cord paralysis. Further genetic and clinical studies of X cranial nerve involvement in heredodegenerative disorders are warranted.

Autosomal dominant spinal muscular atrophy: a clinical and genetic study

A clinical and genetic study of 6 kindreds (13 patients) with autosomal dominant spinal muscular atrophy is presented. Evidence is presented to indicate that two separate autosomal dominant genes are involved. One of these causes clinical disease with onset in early childhood (birth--8 years), which is relatively benign and in which proximal selectively of muscle involvement is not marked. A separate autosomal dominant gene causes a disease with onset in adult life (median age 37 years), showing marked initial proximal selectively; this disease may be more rapid in its clinical progression. Penetrance of both genes approaches 100%. Incidence figures are presented; less than 2% of all cases of childhood onset spinal muscular atrophy, but 30% of adult onset cases, are due to an autosomal dominant gene transmitted from an affected parent. Implications for prognosis, diagnosis and genetic counselling are discussed. A review of 11 kindreds of dominant spinal muscular atrophy in the literature is presented.

Distal chronic spinal muscular atrophy involving the hands

Six patients are described with a history of slowly progressive wasting of the muscle of the hands and forearms extending over periods of up to 20 years. The clinical, radiological, and electrophysiological findings were consistent with a diagnosis of chronic anterior horn cell degeneration. It is suggested that the patients are affected by a form of distal chronic spinal muscular atrophy affecting the hands.