Activation of renin-angiotensin system does not cause skeletal muscle cramps during hemodialysis

Activation of the renin-angiotensin system usually occurs during hemodialysis and in hemodialyzed normal dogs parallels reductions in blood flow to a tissue group that is largely composed of skeletal muscle. To determine if excessive activation of this system might cause dialysis-associated skeletal muscle cramps in some patients, we conducted a double-blind, randomized and balanced trial in which 5 patients with frequent dialysis-associated cramps were each given either a 25 mg oral dose of captopril or placebo 1 h before 8 consecutive dialyses. Captopril increased the frequency of dialyses complicated by skeletal muscle cramps in 1 patient and did not affect cramp frequency in the other 4 patients. Predialysis plasma renin activity (PRA) averaged 3.9 ng/ml/h (+/- SD) and was the same as in unselected hemodialysis patients. Following captopril, PRA increased by an average of 2.2 +/- 0.7 times, similar to the 2.6-fold increase that was reported when this drug was used to prevent dialysis-associated hypertensive crises. However, hemodialysis by itself did not activate the renin-angiotensin system as consistently in patients with frequent dialysis-associated skeletal muscle cramps as in unselected hemodialysis patients and the ratio of post- to predialysis PRA averaged 1.0 +/- 0.6. We conclude that the renin-angiotensin system does not mediate, and that its activation during hemodialysis may actually help prevent, dialysis-associated skeletal muscle cramps.

Writer's cramp

Writer's cramp has been recognized for over a century, and originally was construed as a physical motor disorder. However, an unfortunate use of the descriptive term 'professional neuroses' to describe this and other similar task-specific conditions, coupled subsequently with fashions in psychiatry, led to the mistaken belief that writer's cramp was due to psychic rather than motor pathology. Evidence has accumulated in recent years showing that writer's cramp is a real focal motor disorder, with a close relation to dystonia. This article summarizes what is known about the aetiology, clinical features, pathophysiology and treatment of writer's cramp and analogous occupational cramps, with the aim of drawing the attention of neuroscientists to this common, bizarre and poorly understood condition.

Syndrome of continuous muscle fibre activity confined to the legs

We report a 35-year-old woman with painful muscle cramps in both legs, this being the only symptom of the syndrome of continuous muscle fibre activity. Diagnosis was confirmed by electromyography during sleep.

The syndrome of continuous muscle fibre activity: light and electron microscopic studies in muscle and nerve biopsies

Histological and ultrastructural studies were performed on nerve and muscle biopsy specimens from two patients with the syndrome of continuous muscle fibre activity. The characteristics of muscle biopsies were as follows. By light microscopy, internal nuclei were present in many of the fibres. By electron microscopy many fibres contained filamentous bodies and subsarcolemmal aggregates of mitochondria embedded in the peripheral zone of cytoplasm, and occasional mitochondria with disorganized or branched cristae were larger than normal. Biopsies of sural nerves revealed a decreased number of myelinated fibres, clusters of small myelinated fibres, and evidence of active axonal degeneration such as disintegrated myelin segments and degenerated axon components, as well as loss of axonal contents. With the present biopsy findings, it is suggested that the pathological process of this syndrome affects peripheral nerves as well as muscles.

Evidence of neuromuscular hyperexcitability features in patients with primary fibromyalgia

The presence of clinical and electromyographic (EMG) features of neuromuscular hyperexcitability (NMHE) and of the commonly associated neurovegetative disturbances (NVD) were investigated in 49 patients with primary fibromyalgia (PF) and in a control group of 33 patients with rheumatoid arthritis (RA). At least two clinical features of NMHE were present in 39%, and at least three NVD in 63% of PF patients. In contrast, only 1 RA control had two NMHE features (p greater than 0.005) and three NVD (p less than 0.001). Moreover, a significant post-ischemic spontaneous EMG hyperactivity was observed in 11 PF patients, and in only 1 control with RA (p less than 0.05). Finally, in patients with PF the number of tender points were correlated with psychological tests for depression (p less than 0.02), and the number of NVD. The present study shows that in patients with PF there is a large prevalence of NMHE complaints and NVD. The potential underlying pathogenetic mechanisms are also discussed.

Reciprocal inhibition between forearm muscles in patients with writer's cramp and other occupational cramps, symptomatic hemidystonia and hemiparesis due to stroke

Reciprocal inhibition of H reflexes in the forearm flexor muscles was examined in a group of 16 patients with writer's and other occupational cramps. The early disynaptic phase of reciprocal inhibition was normal. However, there was a reduction in the amount of later, presynaptic inhibition, when compared with age-matched normal subjects. Similar findings were seen in 2 patients with symptomatic hemidystonia in whom structural brain lesions were present. However, this reduction in presynaptic inhibition was not specific to patients with dystonia. In a further group of 13 patients with hemiparesis or hemiplegia due to stroke, abnormalities of both early and later phases of reciprocal inhibition were found. The patients with spasticity exhibited less disynaptic inhibition than those with normal tone or flaccid limbs. The changes in the presynaptic phase of reciprocal inhibition did not correlate with the clinical signs of spasticity and increased muscle tone. These results provide objective evidence of a physiological basis for the action or task-specific focal dystonias such as writer's cramp.

[The state of muscle cramp disease]

A 65-year-old man presented with daily, almost continuous muscle cramps and painless muscle contractions eight years after being diagnosed as having rheumatoid arthritis. Both cramps and contractions were present at rest, were accentuated by stress and disappeared during sleep. By night-fall the patient was plunged into an extremely disabling condition due to the continuous cramps present in the orofacial, trunk, neck and limb musculature. He even had difficulty speaking. EMG studies demonstrated that both cramps and painless contractions appeared synchronously in muscles innervated by different peripheral nerves. A state of central hyperexcitability is the probable cause of this clinical picture which has remained unchanged over the last six years.

Reciprocal inhibition in patients with hand cramps

We studied inhibition of median nerve H-reflex produced by radial nerve stimulation in both arms of 14 patients with hand cramps and 15 normal volunteers. Median nerve stimulation was delivered 1 and 0.5 msec before and 0, 0.5, 1, 2, 10, 20, 30, 50, 75, 100, 200, 500, and 1,000 msec after radial nerve stimulation. Recordings were from surface electrodes positioned over flexor carpi radialis. We identified three periods of attenuation of median nerve H-reflex amplitude in the control group. When radial nerve conditioning stimuli were delivered simultaneously, 10 and 75 msec before median nerve test stimuli, H-reflex amplitude diminished to 47%, 61%, and 69%. In the patient group we also found three periods of attenuation at the same delays, but the amount of attenuation was significantly less than in controls. Dividing the patients into two groups, dystonic hand cramp and simple hand cramp, both showed less inhibition than the control group, but the abnormality was greater in the dystonic cramp group. This test is the first to demonstrate physiologic disturbance in patients with hand cramps.

Hand cramps: clinical features and electromyographic patterns in a focal dystonia

We studied 19 patients with hand cramps, including writer's cramp, typist's cramp, piano, and guitar player's cramp. EMGs were recorded while patients performed the task triggering the cramps. Ten patients with dystonic cramps had EMGs with generalized muscle spasms with co-contraction of agonist and antagonist muscles. In three patients with simple cramps that involved one to three fingers, specific muscle groups showed co-contracting bursts that lasted longer than normal. The physiological abnormalities support the interpretation that hand cramp is a focal dystonia, characterized by both excessive muscle activity and defective fine motor control.

Degenerative cerebellar ataxia and focal dystonia

Eight patients with a variety of degenerative cerebellar ataxias are described in whom focal dystonia was a prominent presenting feature.

The cause of leg cramps and knee pains: an hypothesis and effective treatment

Cramps and pains of the lower extremities along with stiffness and pains in the knees are common complaints in the general population. Because the etiology and development of these disorders are poorly understood, treatment has been haphazard, for the most part unsuccessful, and occasionally dangerous. The diagnosis of "arthritis" is often incorrect; when osteoarthritis is present it is frequently not the cause of the pain. We name these maladies the "stiff leg syndrome" and hypothesise that they are caused by muscle and tendon shortening which came about as a direct result of modern civilization; the popular practice of squatting close to the ground to defecate, cook and eat was replaced by a more "civilized" practice of sitting high on toilets and chairs. We discuss several simple stretching exercises which mimic the effects of squatting and frequently result in immediate and dramatic relief of symptoms.

Painful muscle cramps. A symptom of liver cirrhosis?

We found an 88% incidence of painful muscle cramps in 33 patients with cirrhosis, as compared to 21% in a matched population without liver disease. The cramps were characterized by severe pain, occurred in calf muscles several times a week (mainly at rest or during sleep), and lasted for a few minutes. No definite etiological factor could be found and the underlying pathophysiology remains obscure, as in most other types of muscle cramps. However, the strikingly high incidence and uniformity of the phenomenon may justify the inclusion of painful muscle cramps among the recognized symptoms of cirrhosis.

The ischemic exercise test in normal adults and in patients with weakness and cramps

Data from 23 normal men and women were used to derive 95% confidence limits for maximum changes in ammonia and lactate values following ischemic forearm exercise. Most normal subjects raised serum lactate and ammonia concentrations more than 20 mg/dl and 100 micrograms/dl, respectively, over baseline values. No significant correlations were found among age, sex, duration of exercise, or estimate of work performed and the maximum ammonia and lactate values achieved. When 70 patients with complaints of weakness, fatigue, or cramps were evaluated, the ischemic exercise test identified 5 patients who proved to have defects in glycolysis or purine metabolism. The test also distinguished those patients with type III glycogen storage disease who lacked debrancher enzyme activity in muscle.

Kennedy disease in an Italian kindred

An X-linked adult-onset neurogenic muscular atrophy, chiefly proximal, with late involvement of the distal musculature and medulla oblongata was present in 4 members of a single kindred. Associated in all patients were gynecomastia, impotence and essential tremor. Frederickson type IV hyperlipemia was present in 1 patient. Hormonal stimulation tests in 2 patients elicited a borderline low testicular response in the younger of the 2 and a pathological response in the older patient. On the evidence of these and previously reported cases, Kennedy disease would appear to be characterized by an X-linked proximal neurogenic amyotrophy of adult onset and by a testicular endocrine deficit.

Physiotherapy and electromyography in muscle cramp

Four cases of muscle cramps, at a sports institute, are presented. Electric activity was increased in cramp due to overload. The influence of stretching, electro- and compression therapies on these increased Electromyographic (EMG) activities was studied. The registration was performed with an EMG-analyser combined with a recorder, using surface electrodes.

The endogenous opioid system in neurological disorders of the basal ganglia

The endogenous opioid peptides have for some time been implicated in the regulation of motor behavior in animals. Recently, however, there is increased evidence to suggest a role for these peptides in the control of human motor functions as well as in the pathophysiology of abnormal movement disorders. Degeneration of opioid peptide-containing neurons in the basal ganglia has been demonstrated in Parkinson's disease and Huntington's chorea, but the clinical significance of these findings is largely unknown. On the other hand, there is evidence that excessive opioid activity may be important in the pathophysiology of some movement disorders such as tardive dyskinesia, progressive supra-nuclear palsy, and a subgroup of Tourette's patients. These findings indicate that diseases of the basal ganglia are possibly associated with alterations in opioid peptide activity, and that these alterations may be useful in designing experimental therapeutic strategies in these conditions.

Primary writing tremor and myoclonic writer's cramp

Four patients with primary writing tremor had a focal, task-specific tremor that responded to anticholinergic drugs. Physiologic features included EMG activity alternating in antagonist muscles, 5- to 20-microV cerebral potentials evoked by stretch of pronator teres, and no C-reflexes. Another patient had myoclonic jerks of the forearm on attempts to write ("myoclonic writer's cramp") that also responded to anticholinergic drugs; EMG activity appeared synchronously or alternating in antagonist muscles. These disorders have features of dystonia and enlarge the spectrum of writer's cramp.

Increased co-activation of the upper limb muscles in writer's cramp

Eleven patients with writer's cramp were studied during the performance of a series of writing and non-writing tasks. Their performance in the tasks and the intensity of contraction in the flexor and extensor muscles of the fingers and elbow (recorded electromyographically) were compared with the results from a group of matched normal controls. The patients showed highly significant increases in muscle activation especially in the triceps muscle which was overactive in all but one of the tasks undertaken. Psychometric testing showed no difference between patients and controls. The results support the view that writer's cramp is a form of focal dystonia in which the disorder of motor control is not confined to writing activities.

[Increased muscular irritability syndrome: treatment with nifedipine. Report of a case]

In 1980 Alberca et al. described a patient with a syndrome of increased muscle irritability, who presented ondulating muscle rolling movements and electrically silent cramps, myoedema and muscle reactions to mechanical stimulation similar to myotonic response, suggesting a disfunction at myofibrillar level. We saw a similar case, of a male patient, 21 years of age, who complained of cramps of severe intensity for the past four years. These cramps were painful in the upper and lower limbs and impaired his locomotion; they were electrically silent. At percussion the patient showed severe idiomuscular contraction, with a period of increased relaxation, similar to a myotonic reaction and also, prolonged myoedema and rolling muscle contractions. Electromyography was normal, as were histochemical and electron microscopy studies. We carried out a therapeutic trial with niphedipine (a calcium antagonist), on the assumption that the patient showed a disturbance of the myofibrillar function--even though physiopathogenesis of the hyperirritability muscle syndrome was not yet clearly defined--and with a basis on the importance of the intracytoplasmatic level of Ca++ free in the muscle contraction mechanism, not only as the initiating factor of the contractile process, but also as a quantitative controller of the mechanic tension development through regulation of the amount of ATP metabolized during muscle activity. Administration of the drug in a dose of 40 mg daily, per os, brought a remission of the symptoms after two weeks, and the patient could walk normally again. On the introduction of a placebo, on two different opportunities, there occurred a recrudescence of the symptoms after about one week's time.(ABSTRACT TRUNCATED AT 250 WORDS)

Hand difficulties among musicians

We describe our experience with 100 musicians in whom occupation-related difficulties developed. The majority, pianists, experienced hand difficulties in midcareer (average age, 31 years). These were described as "pain, tightening, or weakness" of the right hand or arm or drooping of the fourth or fifth fingers. These difficulties led to loss of control (34%) or diminished facility (18%), endurance (18%), or speed (18%) while playing trills, arpeggios, or octaves requiring fast, forte finger movements. Most commonly found were inflammatory disorders of tendon or joint (45%) or disorders of motor control (24%). Less likely were entrapment of peripheral nerves and noninflammatory tendon or joint disorders.

Writers' cramp-a focal dystonia

We have examined 29 subjects with writers' cramp (and 4 with typists' and one with pianists' cramp) and have noted two major groupings, simple and dystonic. We have observed spread from one to the other. We have seen repeatedly, in patients with isolated simple writers' cramp certain subtle physical signs which are found also in other basal ganglia diseases. We have noted also the frequent association of other features of segmental and generalized dystonia in patients with dystonic writers' cramp. We have demonstrated that patients with isolated writers' cramp have no higher an incidence of psychiatric disturbance, as judged by formal Present State Examination, than the normal population. We conclude that isolated writers' cramp is a physical illness rather than a psychological disturbance, and that it is a focal dystonia.

Familial myoadenylate deaminase deficiency and exertional myalgia

In 14 members of four families with a hereditary syndrome of exertional myalgia, five of eight muscle biopsies from symptomatic individuals showed histochemical and biochemical absence of myoadenylate deaminase (MADA). In the others, MADA biochemical activity was normal in two and reduced but not absent (intermediate level) in one. Asymptomatic relatives had normal histochemical MADA activity, but three had intermediate biochemical levels. In a survey of 302 routine muscle biopsies, 3 of 36 patient with myalgia had absence of MADA. Three of 266 biopsied for other conditions were MADA-deficient. Despite some inconsistencies, MADA deficiency seems to be relevant to this clinical syndrome.

Familial cramps and muscle pain

A family with a disorder characterized by muscle cramps that cause painful posturing of the hands and feet was studied. Three generations are affected and the trait is transmitted by autosomal dominant inheritance. The disorder begins in childhood and does not seem to be progressive. A primary abnormality in the motor neuron is suspected on the basis of electrophysiological studies.

[Cutaneous and muscular unmyelinated afferent fibres. Clinical, histological and experimental study. Possible explanation of muscular cramps (author's transl)]

Unmyelinated afferent fibres are the most numerous of the whole afferent component. Their function in nociception is now well established. However some recent data allow to think that their function is much more complex. Cutaneous unmyelinated afferences are evaluated in controls and in 3 groups of patients (painful neuropathies, painless neuropathies with hypesthesia, diabetic neuropathies). Amyelinic myelinic ratio is not in accordance with the gate control theory. Muscular afferent fibres are studied, especially the lateral gastrocnemius soleus nerve of cat. Their predominance is obvious. Our study was conducted by recording single unit activity from a micro electrod inserted in dorsal root ganglia. But 45% of unmyelinated fibres are not activated by various algesic stimuli. It is suggested that they have a function in cardio-pulmonary adaptation to effort and possibly segmental vascular control as homonymous reflex effect on moto-neuron. Their several properties are a possible explanation of muscular cramps.

Colonic motility in proctalgia fugax

Intraluminal pressure recordings were obtained from the rectum and sigmoid colon in two patients experiencing attacks of proctalgia fugax. In each patient the pain appeared to result from contractions of the sigmoid colon, and not from spasm of the levator ani, rectal wall muscle, or anal sphincters, all of which have previously been suggested as the source of such pain. Proctalgia fugax therefore appears, at least in some patients, to be an unusual variant of the irritable bowel syndrome, in which pain is referred from the sigmoid colon to the rectum.

Analysis of tonic muscle activity and muscle cramps during hemodialysis

A problem associated with some patients undergoing hemodialysis is the presence of muscle cramps. As the etiology of these cramps is still unknown, the purpose of this study was to evaluate tonic muscle activity and muscle cramps during hemodialysis. Forty-six complete dialysis treatment sessions were studied. Electromyographic (EMG) activity was recorded from a leg muscle in patients who cramped and control patients who did not cramp. EMG was analyzed via a minicomputer for each minute of recording time. Results indicated the mean muscle cramp latency from start of dialysis was 248 minutes. Average muscle cramp was 10 minutes in duration and took three minutes to develop and seven minutes to fully dissipate. Tonic EMG activity in patients with muscle cramps showed a continued increase throughout the latter part of dialysis whereas the control patients showed a continual decline. The results suggest that the latent increase in EMG activity may be causally related to muscle cramps and may be a useful predictor as to the onset of muscle cramps during hemodialysis.

Post-tetanic mechanical tension and evoked action potentials in McArdle's disease

The tension produced by the cramp evoked in the adductor pollicis muscle by repetitive stimuli to the nerve (20/s for 50 s) and by full voluntary effort in the brachial biceps was measured in a patient with McArdle's disease. The contracture was 17% of the peaktetanic tension, and was not associated with action potentials. Twitches superimposed on the contracture were at most diminished to half, as were their action potentials. Both slow and fast muscle fibres participated in the contracture. The contraction time of the twitches elicited after the tetanus was prolonged more in the patient than in a normal subject of the same age. There was evidence of delayed firing, first observed 90 seconds after the peak of the contracture. The patient had electromyographic and histological signs of myopathy.

Neuromyotonia. Report of a case

The authors report the case of a 67-year-old man, affected by diffuse spasms evoked by ischemia and voluntary and reflex movements electromyographically characterized by an intense repetitive activity. There was also a modest and diffuse muscle wasting with lower limbs areflexia; no myokymia. The EMG showed severe neurogenic changes and a considerable reduction of the MMCV in the lateral popliteal nerve area.

Hypothenar Dimpling. A peripheral equivalent of Hemifacial Spasm?

In two patients, the skin over both hypothenar eminences underwent intermittent, spontaneous, irregular, dimpling contractions. The dimpling was benign, and was the result of spontaneous discharge of motor units in the palmaris brevis muscle. Electrophysiological investigations localized the site of origin of the discharge to the ulnar nerve, possibly at the wrist, but there was no clinical or physiological evidence of neuropathy or of nerve compression. In many respects, the clinical and electrophysiological features of hypothenar dimpling resemble hemifacial spasm.

Myotonia congenita with painful muscle contractions

We present a family with dominantly inherited myotonia congenita and painful, electrically silent muscle contractions after exertion. In two family members, painful muscle contractions occurred coincident with hypothyroidism, and improved after thyroid replacement therapy. It is probable that this family represents a disease that is similar to but distinct from the dominant form of myotonia congenita.