Biomedical subjects
S Chokroverty
Publications and source records attributed to S Chokroverty.
The exercise test distinguishes proximal myotonic myopathy from myotonic dystrophy.
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Median-ulnar anastomosis to thenar, hypothenar, and first dorsal interosseous muscles: collision technique confirmation.
Median-ulnar anastomosis (Martin-Gruber anastomosis; MGA) is traditionally diagnosed based upon changes in compound muscle action potential (CMAP) amplitude following proximal stimulation. We describe a rare patient with a MGA innervating thenar, hypothenar, and first dorsal interosseous muscles. Proximal stimulation, however, evoked CMAPs with striking changes in morphology and area but only minimal amplitude changes, due to concomitant diagnoses of carpal tunnel syndrome and polyneuropathy. Collision studies were therefore required for diagnostic confirmation of the MGA.
Needle cervical root stimulation may be complicated by pneumothorax.
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Carpet carrier's palsy: musculocutaneous neuropathy.
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AAEM case report #13: diabetic amyotrophy.
A case fulfilling the criteria for the diagnosis of diabetic amyotrophy is reported. Based on the clinical and electrodiagnostic features, it is concluded that diabetic amyotrophy is a recognizable clinical entity that can be differentiated from other diabetic neuropathies. The site of the lesion and the pathogenesis in diabetic amyotrophy remain controversial. The course of the illness is variable with gradual, but often incomplete, improvement.
Sleep and degenerative neurologic disorders.
This article summarizes sleep disturbances in a variety of neuro-degenerative diseases, including Parkinson's disease, multiple system atrophy, and amyotrophic lateral sclerosis. Sleep complaints in these conditions include insomnia, hypersomnia, abnormal motor activity and behavior during sleep, sleep-related breathing problems, and circadian rhythm sleep disturbances. Clinical examination followed in selected cases by polysomnographic, multiple sleep latency, and other laboratory tests is essential for correct diagnosis and treatment of these sleep disturbances.
Diabetic amyotrophy: current concepts.
Diabetic amyotrophy is a disabling illness that is distinct from other forms of diabetic neuropathy. It is characterized by weakness followed by wasting of pelvifemoral muscles, either unilaterally or bilaterally, with associated pain. Sensory impairment is minimal in the cutaneous distribution sharing the same root or peripheral nerve as affected musculature. Most commonly, the onset is in middle age or later, although it may occur in youth. A concomitant distal predominantly sensory neuropathy may be present. Electrodiagnostic studies are most often consistent with a neurogenic lesion attributable to a lumbosacral radiculopathy, plexopathy, or proximal crural neuropathy. The natural course of the illness is variable with gradual but often incomplete improvement. The site of the lesion and the pathogenesis of diabetic amyotrophy remain controversial. Recent studies suggest a role for immunomodulating agents in certain types of diabetic neuropathy, including diabetic amyotrophy.
Randomized, Double-Blind, Placebo-Controlled Study of Clonidine in Restless Legs Syndrome.
Ten patients with idiopathic restless leg syndrome (RLS) were asked to rate their symptoms at baseline during 2 weeks of placebo and 2 weeks of clonidine treatment by using a four-point scale. On two consecutive nights of each treatment period, polysomnography (PSG) and actigraphic studies were performed. Patients subjectively reported improvement in leg sensations (p = 0.02) and motor restlessness (p = 0.001) while receiving clonidine (mean = 0.5 mg/day). On PSG testing, sleep onset occurred faster with clonidine (12 minutes) compared with placebo (30 minutes) and baseline (47 minutes) (p = 0.006). Adverse findings associated with clonidine treatment included decreased percent REM sleep in the clonidine group (4%) compared with placebo (16%) and baseline (16%) (p = 0.001) and increased REM latency in the clonidine group (195 minutes) compared to the placebo (70 minutes) and baseline groups (89 minutes) (p = 0.028). There were no significant changes in total sleep time, stage 1 and 2 sleep, sleep efficiency, awakenings, arousals or periodic limb movements in sleep. There was a nonstatistical trend toward and increase in stage 3 and 4 sleep and a decrease in motor activity as measured by actigraphic recordings. Globally, seven out of 10 patients felt clonidine was more effective than placebo. Four patients chose to continue clonidine after the study. Clonidine may be an effective treatment for RLS patients who don't have large numbers of sleep-disrupting periodic limb movements but have delayed sleep onset due to leg sensations and subsequent motor restlessness.
A questionnaire study of 138 patients with restless legs syndrome: the 'Night-Walkers' survey.
After verifying the diagnosis of restless legs syndrome (RLS) in 105 patients who are part of a nationwide support group, we undertook a telephone survey of their symptomatology. We then compared the answers with those of 33 of our own RLS patients who had undergone a neurologic examination and had a periodic limb movement in sleep (PLMS) index of > 5 (number per hours of sleep). Although RLS has generally been considered to be a condition of middle to older age, the results for the support group, and for our patients, are similar in that more than a third of the patients in each group experienced their first symptoms before the age of 10. Initial lack of diagnosis or misdiagnosis by a physician were common and the symptoms were commonly thought to be psychogenic whatever the age of onset. In some cases, young age-onset RLS was severe from the start. For younger age-onset patients whose symptoms were severe enough to seek immediate medical attention, confounding or misdiagnosis included "growing pains" and attention deficit hyperactivity disorder. However, medical attention was generally not sought until the fourth decade. Most respondents stated that this was because their symptoms were mild at onset and then progressed. In the older age-onset patients, misdiagnoses also included skin irritation, arthritis, and malingering. A total remission of symptoms of a month or more was present in at least 15% of the individuals in all groups surveyed. More than 50% of the respondents know of one or more first-degree relatives affected by RLS. Five of our 33 patients had RLS initially triggered either by diabetic peripheral neuropathy or lumbosacral radiculopathy.
Heat-sensitive myotonia in proximal myotonic myopathy.
Two siblings with proximal myotonic myopathy (PROMM), a hereditary disorder, had predominantly proximal weakness, pain, and gait impairment aggravated by warm temperatures. EMG of the deltoid showed sparse abnormal spontaneous activity at room temperature and with cooling. Warming induced frequent myotonic discharges and fibrillations. Profuse myotonia recorded at room temperature in the first dorsal interosseous abated following cooling. Repetitive stimulation did not reveal a decrement recording from distal muscles, but recording from the deltoid, in the one patient tested, revealed a significant decrement that did not improve with edrophonium. Myopathic motor units were recorded only in distal musculature. The myotonia of PROMM is provoked by heat and diminished by cold and may have a different physiologic basis than traditional myotonic syndromes.
Thoracic spinal nerve and root conduction: a magnetic stimulation study.
We describe a technique of magnetic coil (MC) stimulation of the thoracic spinal nerves and roots in 12 normal subjects and a patient with diabetes mellitus. We kept the MC flat against the vertebral column in the midline over T-7, T-8, and T-9 spinous processes and obtained compound muscle action potentials from the upper rectus abdominis, external oblique, and intercostal muscles. We obtained mean latencies to these muscles after stimulation in the posterior axillary line. We noted that the onset latencies remained fixed despite increasing the intensity of stimulation from 30% to 100% and on moving the coil up to 3 cm lateral to the spinous processes suggesting that the stimulation of the fastest conducting fibers was occurring at a fixed site, most likely at the intervertebral foramina. Prolonged latencies in the diabetic patient confirmed the diagnosis of radiculoneuropathy.
Magnetic brain stimulation: safety studies.
We describe short-term and long-term safety studies after low repetition rate magnetic brain stimulation in 10 normal subjects. We obtained quantitative EEG data, psychometric test results, serum prolactin and cortisol levels before and after brain stimulation. EEG and psychometric data were also obtained in 5 of these subjects 16-24 months after the initial experiment. Short- and long-term studies did not show any deleterious effects. Randt delayed recalls, however, showed a transient reduction in the score immediately after stimulation which resolved on retesting in 2 weeks. To address the question of fatigue we repeated Randt tests in 4 subjects before and after magnetic brain stimulation but without the other extensive psychometric, EEG and blood tests. Pre- and post-stimulation scores on this occasion showed no significant difference in these 4 subjects suggesting that the transient changes in the previous Randt score were related to fatigue. We conclude that single-pulse magnetic brain stimulation has no deleterious effects after magnetic brain stimulation.
Painless legs and moving toes: a syndrome related to painful legs and moving toes?
The syndrome of painful legs and moving toes consists of continuous or semicontinuous involuntary writhing movements of the toes associated with pain in the affected extremity. We report a 57-year-old man with a 33-year history of painless and semicontinuous involuntary movements of the toes of the left foot similar to those seen in painful legs and moving toes. There was no family history of movement disorder. The history and physical examination were negative for significant trauma, radiculopathy, or peripheral neuropathy. There were no other neurological findings or involuntary movements. It is unlikely that the involuntary movements were precipitated by neuroleptics or psychosis. CT scan of the head; EEG, CT, and MRI scans of the lumbosacral spine; and EMG and nerve conduction studies of the legs showed no significant abnormalities except for a predominant cocontraction of the left foot flexors and extensors at 0.6-1.2 Hz in a pattern sometimes seen in painful legs and moving toes. We conclude that there is a condition clinically and electrophysiologically similar to painful legs and moving toes that we call painless legs and moving toes, the etiology of which remains undetermined.
Magnetic coil stimulation of the human lumbosacral vertebral column: site of stimulation and clinical application.
We describe the technique of magnetic coil (MC) stimulation of the lumbosacral roots and the possible site of stimulation in 22 control subjects, and the clinical usefulness of MC stimulation in 5 patients with low back pain. We observed 2 components in the compound muscle action potential of the soleus muscle following MC stimulation over the lumbosacral region. The second component had the physiological properties of the H reflex. The conduction time from the anterior horn cells of the lumbosacral spinal cord to the site of nerve root stimulation over the lumbosacral vertebral column was indirectly calculated as between 3.9 and 4.1 msec. Assuming a conduction velocity of 50 m/sec this would represent a distance of approximately 20 cm from the spinal motor neurons. Based on our control and patient data we conclude that the MC stimulation may be an useful technique for the diagnosis of lumbosacral radiculoplexopathy.
Successful treatment of the idiopathic restless legs syndrome in a randomized double-blind trial of oxycodone versus placebo.
In a double-blind randomized crossover trial, oxycodone or placebo was given in divided night-time doses to 11 patients with idiopathic restless legs syndrome (RLS) for 2 weeks prior to appropriate polysomnographic studies. Under double-blinded conditions, patients were asked to do daily ratings of their leg sensations, motor restlessness and daytime alertness on a 1-4 scale for the 2 weeks prior to the polysomnographic studies and for the nights of the polysomnographic studies as well. Leg sensations (p < 0.009), motor restlessness (p < 0.006) and daytime alertness (p < 0.03) were significantly improved on oxycodone as compared to baseline or placebo. Patients were studied polysomnographically under double-blinded conditions for 2 nights in each phase of the protocol. On an average dose of 15.9 mg oxycodone (equivalent to approximately three 5-mg tablets of commercial preparation), there was a statistically significant reduction in the number of periodic limb movements in sleep [(PLMS)/hour sleep (p < 0.004)] and in the number of arousals/hour sleep (p < 0.009) on drugs as compared to baseline or placebo. A statistically significant improvement was also noted in sleep efficiency (p < 0.006) and 10 of the 11 patients preferred oxycodone over placebo. We conclude that oxycodone is an effective treatment for RLS and PLMS.
Human startle reflex: technique and criteria for abnormal response.
Because quantitative norms for the normal audiogenic startle response to repeated stimuli have not been previously reported, we now describe a technique for eliciting the startle response and analysing its habituation with repeated stimuli. We used binaural 105 dB tones delivered in 5 blocks of 4 tones. Successive blocks were separated by a 5 min period without tones stimuli and had progressively shorter inter-stimulus intervals (ISIs) beginning with 5 min in the first block and reducing to 1 min in the final, fifth block. We contrast the response and its habituation in a group of 8 normal subjects with that in a patient with clinically exaggerated startle. Based on the differences observed, we propose that the following criteria may be used to ascertain an abnormally increased startle response: (1) excessive duration of the myogenic response; (2) persistence of extracranial responses after the initial two blocks of stimuli; and (3) reduced habituation of the response (as measured by decreases in response duration and in the area under the curve of rectified EMG for the orbicularis oculi myogenic response). Our patient was abnormal on each of these measures. This result is consistent with past qualitative reports which have indicated that abnormal startle is associated both with excessive startle and with subnormal habituation. Study of further patients with hyperekplexia will be necessary to either confirm our data or modify our proposed criteria.
Propriospinal myoclonus: a neurophysiologic analysis.
We are reporting a neurophysiologic analysis of two patients presenting with thoracoabdominal spontaneous muscle jerks. Polymyographic recordings showed myoclonic bursts with onset in the upper rectus abdominis or lower intercostal muscles followed by rostral propagation to the upper intercostal and caudal propagation to the abdominal muscles by slowly conducting pathways. Jerk-locked back-averaging did not show time-locked cortical or premovement potentials. Peroneal somatosensory evoked response, C-reflex, and intercostal nerve conduction were normal. These findings suggest a generator for the myoclonus in the midthoracic region of the spinal cord with up and down propagation by slowly conducting pathways, such as propriospinal fibers. This type of spinal myoclonus may thus be termed "propriospinal myoclonus," as suggested by Brown et al.