Obstetric brachial plexus palsy.

In a retrospective survey of 46 conservatively treated patients with obstetric brachial plexus palsy (OBPP) the following conclusions were reached. An immediate examination of the neurological status of the neonate root by root is essential for proper analysis of the course of the recovery. Mild cases with C5-C6 root injury (Erb's palsy) have a good outcome and may be treated conservatively. Intermediate cases with C5-C7 root injury with additional drop hand require close observation as early as age 3 weeks when the first electromyographic (EMG) examination is indicated. The second EMG should be performed at age 11-12 weeks. If the function of the brachial biceps muscle is lacking at age approximately 12 weeks (3 months), microsurgical intervention should be considered; such intervention definitely is required at age 5 months if the paresis in the brachial biceps muscle has not recovered. Severe cases with C5-C8 or C5-Th1 root injuries with flaccid abducted arm, wrist drop, claw hand, and possibly head tilt to the contralateral side and Horner's sign should be operated on primarily at age 1-2 months.

Effects of taltrimide, an experimental taurine derivative, on photoconvulsive response in epileptic patients.

Taltrimide is a lipophilic taurine derivative with definitive anticonvulsive effects in experimental epilepsy models. In this study, taltrimide was administered for 6 days, and the effects of the treatment on photoconvulsive response in EEG in eight epileptic patients were evaluated. Discharges provoked by intermittent photic stimulation (IPS) were increased by greater than 50% in four patients after taltrimide treatment. Only one patient had reduction of sensitivity. There was only a slight change in discharges after hyperventilation and no change in spontaneous paroxysms. The effects of taltrimide on photosensitivity appear to be rather specific. The study does not reveal anticonvulsive effects of taltrimide in humans.

Neurophysiological findings in the hereditary presenile dementia characterised by polycystic lipomembranous osteodysplasia and sclerosing leukoencephalopathy.

17 patients suffering from the presenile dementia characterised by polycystic lipomenbranous osteodysplasia and sclerosing leukoencephalopathy were studied neurophysiologically. Noteworthy findings were diffuse slowing, the accentuation of 6-8 Hz parasagittal activity, slowing of the dominant occipital rhythm and, in the late phase when 13 of patients got epileptic seizures, there was paroxysmal activity in the EEG.

Electromyographic and nerve conduction findings in a patient with neuromyotonia, normocalcemic tetany and small-cell lung cancer.

A 57-year-old man with neuromyotonia and normocalcemic tetany as probable paraneoplastic symptoms of small-cell lung cancer was examined neurophysiologically. In EMG, spontaneous action potential generation was demonstrated in peripheral motor axons. There were also time-locked high-frequency discharges after some voluntarily activated motor unit potentials. After electrical stimulation of motor axons, the M-response as well as spinal F-response or H-reflex was often followed by a sequence of oscillating potentials which could last several hundred msec. There was no evident peripheral polyneuropathy. Tetany subsided when carbamazepine therapy was started. The only striking abnormality in extensive laboratory studies was an increase in the plasma noradrenaline value.

Lack of correlation between spontaneous fasciculations and double discharges of voluntarily activated motor units.

We have studied the possible correlation between spontaneous fasciculations and double discharges or voluntarily activated motor units in myelopathies and other proximal neuropathies. Though both these phenomena are common in these diseases, they seem to have no correlation in individual muscles. It is concluded that spontaneous fasciculations and doubling of voluntarily activated motor unit potentials have different sites of origin or different mechanism. For example, if doubling reflects a disturbance of firing in the axon hillock, spontaneous fasciculations may originate in a more peripheral part of the motor axon.

Electromyography in the estimation of nerve lesions after surgical and radiation therapy for breast cancer.

EMG was performed on the upper extremity of the affected side in 55 breast cancer patients who had undergone mastectomy and postoperative radiotherapy. Radical mastectomy caused six latissimus pareses out of 26 patients and seven deltoideus pareses out of 49 patients. Simple mastectomy caused no pareses. As an early complication of radiotherapy five out of 16 patients developed slight EMG changes, most often in the biceps brachii muscle, but no clinical pareses were observed. In the follow-up group (at least 5 years after primary treatment) 18 out of 25 patients had varying EMG alterations. The relative frequency of EMG findings indicates an increasing number of neural changes caused by radiotherapy in the follow-up group. Severe pareses were infrequent as complications of radiotherapy. In neurography of the cutaneous branch of n. radialis a diminution of the amplitude of the sensory response was found one or two months after radiotherapy in the affected side. EMG proved to be useful in estimating both the early and late neural complications of primary treatment of breast cancer and in evaluating patients' capacity for work.

An analysis of double discharges in the human electromyogram.

Different characteristics of double discharges (doublets) of motor units in m. biceps brachii and tibialis anterior were examined. Doublets may occur physiologically at the beginning and termination of muscular effort and at the minimum rhythmic firing frequency, but doublets arising within a regular sequence of motor unit potentials can be regarded as abnormal. In neuromuscular diseases about 3% of motor units showed this firing pattern, but it was never found in intact limb muscles. Most of the abnormal doublets have the following characteristics: the interval between the first and the second component is 9 msec or less (longer intervals up to 22 msec occur very rarely); both components have nearly the same form; the amplitude of the second component is slightly smaller than that of the first; a stepwise or continuous jitter between doublet components is common; doublets recur randomly during a sequence of motor unit potentials; the interval between the doublet and the next MUP is usually about 50% longer than the mean MUP interval. A number of doublets differ, however, in one way or another from the above. The second component of the doublet may differ completely in amplitude and even in form from the first component; or they may fuse. It is thus hardly possible to define the lower limit of the interval between doublet components. Sometimes the post-doublet interval increase is absent. When applying all the criteria there is seldom any uncertainty about the identification of doublets.

Double discharges in neuromuscular diseases.

Double discharges (doublets) of motor units were examined in routine EMG. The material consisted of 132 patients suffering from different neuromuscular diseases and 34 controls in whom the examined muscles were intact. Only m. tibialis anterior and biceps brachii were examined. Activity from at least 10 different motor units per muscle were recorded and analyzed off-line. Modified criteria were used in determining doubling units. Applying the modified criteria no doubling units were found in controls. In myopathies doublets occurred only in myotonic dystrophy and in one case of polymyositis in remission. In neuropathies, the occurrence of doublets was most common in proximal neuropathies. In polyneuropathies and root syndromes doubling units were relatively common, but none were found in exclusively distal neuropathies. It is concluded that doublets have a definite diagnostic value in routine EMG examination.

"Satellite potentials" and the duration of motor unit potentials in normal, neuropathic and myopathic muscles.

Time-locked activity in the EMG was studied in normal, neuropathic and myopathic muscles, using the averaging technique. Normal and neuropathic muscles seemed in most cases not to differ with regard to the frequency nor the quality of "satellite signals", i.e. small and short potentials joining the main component of the MUP with a constant interval, up to 26 ms in duration. In normal muscles 10% of the MUPs and in neuropathic muscles 12% had a satellite, which, when studied, showed no signs of blocking. However, in 2 patients with an apparent old spinal affection both an increased number and an increased latency of satellite signals were found. In the different myopathies studied 45% of the MUPs recorded consecutively were preceded or followed by an often increased number of tiny satellites. Sometimes the satellites joining the myopathic MUP formed a long (up to 60 ms) "tail" after the triggering component. On the basis of our results we conclude that in myopathies the total duration of MUPs is in certain cases pathologically incrased rather than decreased.