[Clinical picture of spinocerebellar ataxia type I (SCA1)]

Spinocerebellar ataxia is a group of diseases with autosomal dominant inheritance heterogenous both clinically and genetically. So called dynamic mutations underlie most these nosological units. The clinical patterns of various SCA types have not yet been defined completely. The purpose of the present report was description of the typical symptoms and signs of type 1 SCA. Seventeen patients from 13 families (M-2, F-15) were studied clinically in detail. The diagnosis was confirmed by DNA analysis. The assessment included neurological status, cognitive functions, the results of EEG, EMG, SEP, VEP, BAER and MRI examinations. The pedigrees indicated autosomal dominant inheritance pattern. The mean age at onset was 35.5 +/- 6.8 years (range 23-45 years) and it suggested negative correlation with the number of CAG repetitions. Cerebellar syndrome limb and truncal, ataxia and dysarthria was present in all cases. Six patients had nystagmus, 3 had slow saccades, 2 had gaze limitation upward, and lateral and 6 had dysphagia. Signs of pyramidal system involvement were found in 10 cases, one had athetotic movements, one had orthostatic hypotension. Two patients had dementia features, 9 had some decline of intellectual functions, mainly with difficulties of memorization, learning and concentration. In 16 cases MRI demonstrated vermis atrophy and atrophy of cerebellar hemispheres, 14 had fourth ventricle dilatation, 8 had flattening of pons base, 8 had narrowing of cervical spinal cord, 8 had dilated CSF spaces over frontal lobes and in 6 cases lateral ventricles were dilated. Electrophysiological peripheral nervous system investigations showed in 16 cases long-standing damage to the motor and sensory peripheral neurons at the level of nerve trunks, more pronounced in sensory nerves. In 13 cases peripheral neuron damage was subclinical. SEP showed in all patients disturbed function of ascending sensory pathways at peripheral and spinocortical levels.

Motor evoked potential studies in Creutzfeldt-Jakob disease

OBJECTIVES

Motor evoked potentials (MEPs) were recorded in 7 cases of Creutzfeldt-Jakob disease (CJD) to asses the involvement of pyramidal motor pathways in these cases. The diagnosis of CJD was confirmed by autopsy in 5 cases and based on clinical data in two cases.

METHODS

Transcranial (MEP-cortex), root magnetic (MEP-root) and electrical stimulation of peripheral nerves (F-wave, direct M-response) were performed. The cortical excitability threshold, F-wave frequency, MEP amplitudes, peripheral motor conduction velocity, standardized distal latencies and central, root, and F-wave conduction times were evaluated.

RESULTS

The results of MEP testing were markedly abnormal. Cortical excitability thresholds were elevated, MEP amplitudes were reduced while the conduction function was rather preserved. The features of functional disturbances and/or loss of upper and lower motor neurons were revealed. They correlated with the advancement of key clinical CJD symptoms (progressive dementia, extrapyramidal and cerebellar signs, myoclonic jerks, mutism and typical periodic EEG changes), while motor lesion signs might only be slight or absent.

CONCLUSIONS

Conduction slowing, if present, seemed to be secondary to axonal lesion.

Peculiarity of soleus motor potentials evoked by transcranial magnetic stimulation and electrical stimulation of tibial nerve

OBJECTIVE

To reveal and discuss the peculiarities of soleus muscle in comparison with electrophysiological features of other leg muscles.

METHODS

Vastus lateralis (L3), tibialis anterior (L4), extensor digitorum brevis (L5) and soleus (S1) muscles were tested at rest. Transcranial magnetic stimulation (TMS) combined which electrical stimulation of relevant peripheral nerves were applied. Cortically evoked motor potentials (C-MEP), peripheral compound muscle action potential (CMAP) and F-wave were recorded. Estimating F-wave conduction time allowed to calculated the central conduction time (CCT-F) within the cortex-spinal motoneurones segment for each muscle.

RESULTS

One could expect that the lower spinal metameric representation of the muscle the longer a corresponding CCT-F. However, a study of 30 healthy subject (60 right and left muscles) reveals a relatively short CCT-F for the soleus muscle. Moreover, the mean amplitude of soleus C-MEP is the lowest, CMAP and F-wave amplitude are the highest and standardised distal motor latency is the longest compared to the analogous parameters for the other muscles.

CONCLUSIONS

The reason for these special features can be attributed probably to a different structure and innervation of the soleus (mainly red, slow, tonic muscle) in contrast to the tibialis anterior and extensor digitorum brevis (mainly white, fast, phasic muscle).

Cortical excitability threshold for distal limb muscles in transcranial magnetic stimulation. Method--normative values

Transcranial magnetic stimulation was carried out in 30 healthy subjects, aged 20 to 55 and 156 to 180 cm tall, in whom cortical excitability threshold was determined for musculus (m.) abductor digiti minimi (ADM) and m. extensor digitorum brevis (EDB). The lowest stimulus intensity causing in the muscle a reproducible potential of an amplitude of 0.1 mV was adopted as the threshold value. The intensity of the stimulus was noted as a percentage of maximum stimulator output, defined as 100% (Magstim 200). In the stimulation of cortical areas for ADM, a circular coil (2.0T-530 V/m) was used while the in case of EBD, a double-cone coil (1.4T-660 V/m) was used. The threshold was noted while the muscle was relaxed and during weak voluntary contraction. The application of the double-cone coil allowed us to obtain for foot muscles similar threshold values as for hand muscles with a circular coil. It was confirmed that the threshold declines with voluntary contraction of the muscles under investigation. Normative values were prepared, with the norm, limits of the norm, outlier values and pathological markers being distinguished.

[Motor segmental conduction times for extensor digitorum brevis muscle: method and normative values]

Electrical stimulation of the peroneal nerves (60 nerves) and magnetic stimulation of the roots (L5) and motor cortex were performed on 30 normal controls. The muscle responses and F wave (peripheral stimulation) were recorded from extensor digitorum brevis muscle (60 muscles). The parameters of examined potentials were measured and the central, root, peripheral motor conduction times, were estimated. The normative values were established as well as formulae of linear regression within the observed correlations with height. The method may be used for electrophysiological diagnosis of patients with motor pathway impairment on the different levels.

[Segmental motor conduction time for abductor of the fifth finger muscle: methods and normative values]

Electrical stimulation of the ulnar nerves (60 nerves) and magnetic stimulation of the roots (C7) and motor cortex were performed on 30 normal controls. The muscle responses and F wave (peripheral stimulation) were recorded from abductor digiti minimi muscle (60 muscles). The parameters of examined potentials were measured and the central, root, peripheral motor conduction times were estimated. The normative values were established as well as formulae of linear regression within the observed correlations with height. The method may be used for electrophysiological diagnosis of patients with motor pathway impairment at the different levels.

Segmental conduction times in the motor nervous system

The study was performed in 30 normal subjects (24 females and 6 males) with an age range between 18 and 55 years and a height range between 154 and 188 cm. Electrical stimulation was applied to the peroneal nerve with simultaneous recording of the orthodromic response (MEP-M) and F-wave (MEP-F) from the tibialis anterior (TA) and extensor digitorum brevis muscles (EDB). Magnetic stimulation of the L5 level and cerebral cortex was applied using different coils with simultaneous recording of responses from the right and left TA and EDB muscles. Mean normative values and formulae of linear regression were established within the observed correlations with height for the parameters measured (latencies) and derived parameters (segmental conduction times). A software system was developed which allows the readout of the selected parameter values from the Mystro device, calculation of the derived parameters, and classification of the results according to 95% confidence intervals for the parameters obtained in the group of normal subjects included in the study. This fast and painless investigation, which carries no risk to the patient, should prove useful in the electrophysiological diagnosis of motor pathway function including the entire length.

[Segmental conduction times in motor pathways for the soleus muscle--methodology and normal values]

The study performed in 30 normal subjects (24F, 6M) with age range 18-55 years and height range 154-188 cm. Electrical stimulation was applied to the tibial nerves and direct response M and F-wave was recorded from right and left SOLEUS (60 examinations). Transcranial and paravertebral (S1 level) magnetic stimulation was applied with simultaneous recording of responses from both SOL. A software system was developed which permitted the redout of parameters (latencies and amplitudes) from Mystro device, calculation of the derived parameters (segmental motor conduction times) and classification of results according to 95% confidence intervals for the parameters obtained in the group of normal subjects included in the study. Report form was prepared which on line gave the results of individuals examinations. The fast and painless investigation should prove useful in electrophysiological diagnosis of motor pathway function including the entire length.

The F-wave in the vastus lateralis M. and the segmental motor conduction times for L2/L4 motoneurons

The study was performed in 30 normal subjects. Electrical stimulation was applied to the femoral nerves and the muscle evoked potential (CMAP) together with their late components were recorded from the vastus lateralis muscle bilaterally (60 nerves). Features of the late component demonstrating its antidromic nature (F-wave) were proved. Additionally, in each subject transcranial cortical (C) magnetic stimulation and root (Rx) magnetic stimulation at the level of the L3-L4 was applied. The measured latencies of respective motor evoked potentials C-MEP (relaxed muscles), CA-MEP (activated), Rx-MEP as well as the latencies of peripheral CMAP and F-wave allowed the calculation of the derived parameters, i.e. segmental times of motor conduction: central, root and peripheral. The normative values were established. The F-wave measurement also allowed for the calculation of the so-called real central conduction time, which proved to be significantly shorter than the corresponding times previously established for the lower situated L4/S1 motoneurons. This finding suggests usefulness of the method in the precise diagnosis of the lumbosacral spinal enlargement.

[Dermatomal somatosensory evoked potentials from L3, L4, L5 and S1 spinal roots in healthy subjects]

Dermatomal somatosensory evoked potentials (DSEPs) were recorded in 62 healthy volunteers aged from 15 to 65 years (mean 36.8 +/- 12.9 years) with height from 1.5 to 1.92m (mean 1.69 +/- 0.10m). The aim of the study was to establish normal values for L3, L4, L5 and S1 dermatomes and to introduce this method for the neurophysiological diagnosis of chronic lumbosacral pain and disc disease. The signature areas of dermatomes in both legs separately were stimulated according to the method described by Sedgwick and Katifi (1985). DSEPs were recorded from the scalp electrodes placed at Cz', referred to Fpz. The latencies and amplitudes of consecutive components of DSEPs: N33, P40, N50, P60, N75 and side to side differences were measured and evaluated. Statistical analysis of the results revealed significant positive correlation of DSEPs latencies as a function of height. The correlation of amplitudes with height was less significant. Age, on other hand, showed only negative correlation with amplitudes of later DSEP components. On the basis of the performed analysis the latency of P40 and amplitude of P40-N50 seem to be the best parameters for the evaluation of pathological DSEPs. The range of normal value of latencies for stimulated roots should be calculated from regression equation with the subject's height. As regards amplitude, side to side mean value difference above two standard deviation appears to be more useful.

[Routine study of somatosensory evoked potentials in healthy persons. II. Tibial nerve]

60 healthy volunteers ranging in age from 15 to 75 years participated in the study. Tibial nerve was stimulated unilaterally or bilaterally at the ankle and SEPs were recorded along the somatosensory pathway. Determination and readability of the potentials were evaluated according to the stimulating and recording method. After unilateral stimulation, the following derivation system was regarded as most useful in routine testing: L4 - Ic (iliac crest), Th12 - Ic, Cz' - Fz, Fz - Shoulder (and, if possible C7 - Fz). When more detailed spinal cord diagnosis is indicated, bilateral stimulation and recording in montage: Th6 - Shoulder, C7 - Shoulder, C7 - Fz, Fz - Shoulder may be helpful. In the study normal values of parameters of the potentials from certain derivations were presented: latencies, amplitudes, peripheral conduction velocities and central conduction times were taken into account. According to our own results (correlative analysis of SEP parameters) and the results of other authors, interpretation of the potentials on various levels of the ascending somatosensory pathway was discussed.

[Routine study of somatosensory evoked potentials in healthy persons. I. Median nerve]

The study was performed on 62 healthy volunteers (123 nerves) using standard technical parameters. In every case the median nerve was stimulated at the level of II + III fingers and at the wrist. This enabled us to compare potentials evoked by sensory versus mixed nerve stimulation. It has been shown that a reliable evaluation of the somatosensory system is provided by stimulation of mixed nerve. The following montage seems to be the most useful in routine diagnosis. Erb's point - Erb's point, C VII - Fz, Fz - Shoulder, C3,4 - Fz. Additionally, according to clinical situation. C VII - Shoulder and C II - Fz derivations may be used. The Fz - Shoulder derivation enables to record far-field potentials and to control the effect of Fz reference on the waveform of potentials in order derivations. In the study normal values of the main median nerve SEP parameters are presented.

[Computer-assisted evaluation of the status of the peripheral nervous system in alcoholics]

The authors present the principles of work of a computer system destined for evaluation of the results of routine electrophysiological examination of two muscles and four sensory nerves in alcohol-dependent subjects. The range of examinations and the programme based on discrimination analysis make possible, as shown in own investigations, an objective and complete evaluation of the state of the peripheral nervous system in these subjects. The programme is owned by the EMG laboratory of the Institute of Psychiatry and Neurology in Warsaw where it was introduced for clinical diagnosis, but it may be made available to other persons interested in these problems. An electromyograph with a stimulator with current exit averager and minicomputer, e.g. Commodore 64 with a printer are necessary.

[Comparison of electrophysiologic changes in persons with alcoholic polyneuropathy and polyneuropathy caused by carbon disulfide]

A group of 39 patients with alcoholic polyneuropathy (Alc) and another group of 33 patients with carbon disulphide polyneuropathy were studied by electrophysiological methods using an identical programme, and the results were compared. In both groups evidence was found of damage to the peripheral neuron of the type of axonal neuropathy with signs of axonal loss, with moderate slowing down of conduction velocity and with associated signs of regeneration. The dynamics of changes in the Alc group was greater. The cause of a slower rate of changes in the CS2 group seems to be related to a more gradual exposure to the damaging agent, while in alcohol-dependence the toxic agent has a more acute action, with remissions during abstinence and exacerbations during increased alcohol consumption.

[Process of retrograde axonal degeneration in amyotrophic lateral sclerosis in the light of clinical electrophysiological studies]

Correlation analysis was performed comparing the parameters of 30 electrophysiological records obtained in a group of 28 SLA patients. The obtained results suggest that in this primary neuronal disease there is evidence of retrograde degeneration of axons (dying back). Differences in the degree of progression of this pathological process at different levels of spinal innervation enable the recognition of the sequence of electrophysiological changes taking place in the peripheral parts of the axons.

[Neurologic disorders in acute intermittent porphyria]

In a material of 28 patients with acute intermittent porphyria and 2 with mixed porphyria neurological disturbances occurring in acute attach and the degree of their persistence during remission were analysed. The obtained results indicate that the symptoms of acute attach are neurogenic. In the acute phase of the disease a reversible disturbance of function develops in the first place in the nerve fibres with acetylcholine-type of impulse transmission. Clinically detectable permanent signs of polyneuropathy were observed only in some cases with most severe and prolonged acute attack.

Porphyric polyneuropathy and its pathogenesis in the light of electrophysiological investigations

Twenty-four patients with acute intermittent porphyria were examined by means of routine electromyographic (EMG) tests, measurements of motor and sensory conduction in peripheral nerves and stimulation fatigue tests. The EMG results gave evidence of an initial, reversible disorder of function of the peripheral neuron, only sometimes followed by evidence of axonal degeneration of the "dying back" type. In stimulation fatigue tests there was some evidence of potentiation but none of fatigue. Attention is drawn to some analogies between the electrophysiological changes in porphyric polyneuropathy and in botulism. It seems that the pathogenesis of porphyric polyneuropathy may be dependent upon a block of cholinergic endings.

[Neuromuscular excitability and conduction in cases of hypoparathyroidism]

The patients with hypoparathyroidism were studied carrying out: a) tetanic test (PT) for assessment of the degree of neuromuscular excitability and b) double stimulus test (PBP) for assessment of the efficiency of neuromuscular conduction. In six patients low values of calcium, high values of phosphorus and normal values of magnesium were found. In the remaining patients calcium level was decreased also but the phosphorus level was normal, while that of magnesium was low. In all patients the PT was normal while the PBP showed in the first group reduced efficiency of conduction and in the remaining cases increased neuromuscular conductivility. The possible interpretation of obtained results is discussed.