Distal spinal muscular atrophy as a major feature in adult-onset ataxia telangiectasia.

The authors report four adult-onset ataxia telangiectasia (AT) patients belonging to two families lacking pronounced cerebellar ataxia but displaying distal spinal muscular atrophy. AT was proven by genetic studies showing ATM mutations and a reduced level of ATM. ATM activity, as measured by phosphorylation of p53, was close to normal, indicating that the p53 response is not the only factor in preventing neural damage in anterior horn cells in AT.

Treatment for severe palatoclonus by occlusion of the eustachian tube.

PURPOSE: Surgical blocking of the eustachian tube is presented as an ultimate treatment option in a 11-year-old suicidal boy with a therapy-resistant, persistent clicking tinnitus caused by myoclonus of the levator veli palatini. PATIENT: An 11-year-old boy decompensated psychologically as a result of loud and objective tinnitus. The tinnitus could be heard easily by an examiner by bringing his own ear at a distance of approximately 20 to 30 cm to the left ear of the patient. No neurologic etiology for the tinnitus could be traced. Pediatric psychiatric evaluation resulted in a recommendation to perform, as a last resort, an experimental surgical option like blockage of the eustachian tube. INTERVENTION: Treatment with Tegretol (Novartis, The Netherlands) had no effect. Treatment with Dysport (Ipsen) botulin toxin with 30 to 60 U was temporarily effective. Finally, 60 U were not effective anymore. As last refugium, a surgical blockage of the eustachian tube has been performed, first with bone cement and later by a more conventional surgical blockage of that bony tube. OUTCOME: After surgical blockage of the bony part of the eustachian tube, the objective tinnitus disappeared. Blockage of the protympanum by bone cement resulted in only 1 year of successful blocking. After recurrence of the tinnitus combined with aeration of the middle ear, a second surgical transcanal approach was successful in blocking the eustachian tube. With a grommet, the hearing level remained within 10 dB for 0.5 to 8.0 kHz.

Mild axonal neuropathy of children during treatment for acute lymphoblastic leukaemia.

Neurophysiological functioning was studied prospectively in children treated for acute lymphoblastic leukaemia with a low dose vincristine regime (8 x 1.5 mg/m2/dose), to obtain more insight into vincristine neuropathy. A WHO neurotoxicity score was estimated and vibration sense and electrophysiological measurements were taken at standardized times during vincristine treatment. The WHO neurotoxicity score showed decreased or disappearance of Achilles tendon reflexes, and mild sensory disturbances, but a grade 3-4 neurotoxicity was not demonstrated by any of the children. Vibration perception thresholds increased progressively during treatment and amplitudes of action potentials of peroneal and sensory ulnar and median nerves decreased, whereas nerve conduction velocities stayed unchanged. Both vibration perception thresholds and the electrophysiological findings hardly exceeded the limits of normality. We conclude that children treated for acute lymphoblastic leukaemia with a low dose vincristine regimen have mild axonal neuropathy which may be responsible for the motor problems in these children.

Motor unit potential contribution to surface electromyography.

The background of the bioelectric activity of muscle recorded from the surface of the skin (surface electromyography) in terms of the representation of single motor units of the underlying muscle(s) is not very well documented or understood. An insight into the composition of an electromyogram is essential for the proper interpretation of one of the most widely applied electrophysiological techniques. In the present paper, a study of the contribution of single motor unit potentials to the surface electromyogram is presented. To this end, the decline of different components of the motor unit potential with depth of the motor unit is quantified. Experimentally, the action potentials from motor units at several positions in the muscle were recorded by 30 skin surface electrodes. Simultaneous use of scanning electromyography provided information about the actual position and size of the motor unit. Observed linear log-log relationships between motor unit potential magnitudes and distance indicated the usefulness of a power function to describe the motor unit potential's dependence on recording distance. It is shown that different specific surface motor unit potential characteristics fall off differently with depth. The magnitude-distance relationship is shown to be dependent on the recording configuration (unipolar vs. bipolar recording, including the inter-electrode distance) and the chosen motor unit potential parameter (negative peak amplitude, positive peak amplitude and area).

The motor unit potential distribution over the skin surface and its use in estimating the motor unit location.

The amplitude of a surface electromyogram is dependent on the number of active motor units, their size and the relative position of the recording electrode. It is not possible to interpret the surface electromyogram quantitatively without disentangling these different aspects. In this study the decline of different components of the motor unit potential with increasing radial distance from the motor unit is quantified. Fifty-two motor units in the biceps brachii muscle were studied using 36-channel surface electromyography combined with intramuscular scanning electromyography. Scanning electromyography was used to locate precisely the motor unit. The dependence of the surface motor unit potential magnitude on the radial distance between the motor unit and the recording electrodes can be described fairly well by an inverse power function. The steepness of this function depends on the chosen motor unit potential parameter and the interelectrode distance, but also varies between motor units. The change of the negative peak amplitude of the motor unit potential over the skin surface can be used to give a fairly accurate estimate of the location of the motor unit under the skin surface. We found that for all practical purposes the depth of a motor unit in the biceps brachii muscle can be estimated as 20% of the distance over the skin surface where motor unit potentials can be recorded with higher amplitudes than 50% of the maximal amplitude recorded at the skin surface caused by activity of the same motor unit.

Automatic decomposition electromyography in idiopathic inflammatory myopathies.

Automatic decomposition electromyography (ADEMG) is a commercially available software package with installed reference values that enables the objective measurement of motor unit action potentials (MUAPs). To assess the diagnostic yield of this package in idiopathic inflammatory myopathies (IIM) we performed bicepts brachii ADEMG in 17 patients with polymyositis, dermatomyositis and inclusion body myositis. Results were compared with those in 12 controls, and with the results of conventional EMG of the biceps and other muscles. Decreased mean values for MUAP duration occurred significantly more frequently in IIM patients than in controls; other MUAP characteristics did not differ. In IIM patients, decreased mean amplitude and increased mean number of turns occurred significantly less frequently on ADEMG than did corresponding abnormalities on conventional biceps EMG. Decreased mean values for duration and amplitude, and increased mean values for number of turns were seen significantly less often on ADEMG than corresponding abnormalities on conventional EMG of four different, individually chosen muscles. Overall evaluation of ADEMG resulted in a diagnosis of "possible myopathy" in 1 and "probable myopathy" in 8 patients, whereas overall evaluation of conventional EMG led to a diagnosis "suggestive of IIM" in 13 patients. We conclude that, although measurement of mean MUAP duration might be valuable in IIM diagnosis, our results do not favour the use of biceps brachii ADEMG and the installed reference values for the diagnosis of IIM. We suggest modifications to improve ADEMG's applicability.

Hereditary neuropathy with liability to pressure palsies: a clinical, electroneurophysiological and morphological study.

Clinical, electroneurographic and myographic studies were performed on 99 patients of 13 families having hereditary neuropathy with liability to pressure palsies (HNPP) and on 116 relatives. Diagnosis was confirmed in all families by a nerve biopsy of the index case. Large focal myelin thickenings (tomacula) were found in nerve biopsies of affected persons, whether or not pressure palsies had occurred. By using three electroneurographical parameters it was possible to discriminate between asymptomatic patients and unaffected relatives. Complaints sometimes mentioned in literature as being associated with HNPP such as low back pain, brachialgia and short lasting paraesthesia are not related to HNPP. The hereditary transmission is autosomal dominant with total penetration but variable expression.

Chronic inflammatory demyelinating polyneuropathy or hereditary motor and sensory neuropathy? Diagnostic value of morphological criteria.

The pathological changes generally considered to distinguish chronic inflammatory demyelinating polyneuropathy (CIDP) from hereditary motor and sensory neuropathy (HMSN) are: mononuclear cell infiltrates, prominent endoneurial oedema, and marked fascicle-to-fascicle variability. We evaluated the diagnostic significance of these pathological features which are suggestive of CIDP. Nerve biopsies from 42 dominant HMSN type I cases with a normal disease course were investigated for the occurrence of inflammatory features. A small cluster of mononuclear cells was found in 12% of the cases and marked endoneurial oedema in 21%. Variability in pathology between the fascicles was not observed. The histogram configuration yielded additional information for differential diagnosis. Subsequently, we reviewed the clinical, electrophysiological and morphological features of 18 sporadic cases of chronic progressive demyelinating motor and sensory neuropathy with mainly classic onion bulbs in their nerve biopsies and a disease onset in the first decade. In all these patients DNA investigation for the 17p11.2 duplication was performed. According to the results of the DNA investigation, autosomal dominant HMSN type Ia was diagnosed in eight patients, although in six slight 'CIDP-positive' features were present. A diagnosis was definite or most probable CIDP in eight patients. In two patients no definite diagnosis could be made. Testing for the presence of the 17p11.2 duplication is, therefore, helpful in distinguishing between CIDP and HMSN type I. The diagnosis of CIDP requires careful evaluation of the clinical, electrophysiological and morphological data to avoid false-positive diagnoses of inflammatory disorders.

Hereditary neuropathy with liability to pressure palsies in childhood.

Four children, index cases of families in which autosomal dominant neuropathy with liability to pressure palsies (HNPP) was diagnosed, are presented. Only one child was admitted for evaluation of an acute peroneal palsy, three presented with other symptoms. Polyneuropathy was diagnosed in all four children, in one of their parents and in some sibs. On inquiry, one child and several members of the four families had experienced transient palsies before. Morphological studies of the sural nerves showed frequently large tomacula and a neuropathic process of segmental de- and remyelination, and axonal degeneration. Attention is drawn to the atypical presentation without pressure palsies of HNPP.

Muscle cramp as a feature of neuromuscular disease. Five neuromuscular disorders, accompanied by frequent muscle cramps.

Five case reports of neuromuscular disorders, presenting with frequent muscle cramps are discussed. Clinical diagnosis and pathophysiologic concepts are highlighted.

Clinical diagnosis of muscle cramp and muscular cramp syndromes.

The diagnosis of muscle cramp is based on clinical features. Algorithms are presented for the diagnosis of muscle cramp and cramp syndromes.

Persistent periodic hiccups following brain abscess: a case report.

A case is reported of a patient with periodic persistent hiccups and secondary generalised epilepsy lasting for a period of five years following a right temporal brain abscess. The recurring episodes of hiccups had a ten day rhythmicity and unlike epileptic convulsions were unresponsive to treatment.

Muscle cramp: main theories as to aetiology.

Historically relevant hypotheses on the pathophysiology of muscle cramp are reviewed. Psychosomatic, static, vascular, myogenic and neural theories are highlighted from a clinician's point of view. Modern neurophysiological research leaves little doubt that true muscle cramp is caused by explosive hyperactivity of motor nerves. Several mechanisms may be involved including spinal disinhibition, abnormal excitability of motor nerve terminals and spreading of muscle contraction by ephaptic transmission or axon reflexes.

Bilateral neuralgic amyotrophy induced by interferon treatment.

Neurologic side effects of interferon therapy usually consist of diffuse involvement of the central and peripheral nervous systems. We describe a patient with hairy cell leukemia who developed bilateral neuralgic amyotrophy, sacral radicular irritation, and worsening of a preexistent polyneuropathy during treatment with recombinant interferon. A sample of the patient's cerebrospinal fluid showed an increased protein content and oligoclonal banding. Several weeks after discontinuation of interferon therapy, Mees-Beau lines became evident on the patient's fingernails. The findings in this patients, as well as those recently reported by others, show that focal neurologic disturbances may be induced by interferon therapy. The clinical picture of neuralgic amyotrophy is briefly reviewed.

A rapidly progressive autosomal dominant scapulohumeral form of spinal muscular atrophy.

Three patients from a large pedigree are described who had autosomal dominant spinal muscular atrophy that became manifest between the end of the fourth and the sixth decade. The disease progressed rapidly without evidence of corticospinal tract dysfunction, and within 3 years the patients died from respiratory failure.

Our experience with Freilinger's method for dynamic correction of facial paralysis.

Eight patients with unilateral facial paralysis of differing aetiology and duration were treated according to Freilinger's method, which includes cross-face nerve grafting and six to eight months later, transposition of a denervated (temporal) muscle flap to the nasolabial area. The end of the cross-face nerve graft is inserted into the muscle flap. Our experience and results with this technique are discussed. It is clear that the combination of cross-face nerve grafting and transposition of a denervated muscle flap is a valid principle. However, a muscle with a greater excursion and one that is easier to denervate is to be preferred to the temporal muscle.

Off-response: its clinical incidence in very young children.

Off-responses to repetitive photic stimulation may be of various shapes. In particular, very young children with respiratory distress showed a typical off-response. This reaction is rather peculiar; it consists of a triphasic, very sharp wave followed by a depolarization of longer duration. The latency is about 200 msec. This off-response seems to be the reaction of an immature brain.