1/6. 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.- - - - - - - - - - ranking = 1keywords = myokymia (Clic here for more details about this article) |
2/6. Isaacs' syndrome with muscle hypertrophy reversed by phenytoin therapy.A 16-year-old boy was seen for severe episodic muscle cramps and generalized myokymia, consistent with Isaacs's syndrome. Bilateral calf hypertrophy (46-cm calf circumference) and ankle areflexia were noted. He was treated with phenytoin sodium, 300 mg/day. Within three months there was marked decrease in myokymia, total relief of cramps, return of ankle reflexes, and 6-cm reduction in calf circumference. We suggest that the excess muscle activity in Isaacs's syndrome may be responsible for the associated phenomena of muscle hypertrophy and areflexia.- - - - - - - - - - ranking = 2keywords = myokymia (Clic here for more details about this article) |
3/6. Motor neuron 'bistability'. A pathogenetic mechanism for cramps and myokymia.In three patients suffering from chronic muscle cramps, spasms and myokymia, these involuntary contractions were triggered in the triceps surae, quadriceps, flexor carpi radialis or flexor digitorum by means of single or short-train stimulation of homonymous Ia afferents, elicited by electrical means or tendon taps. In some cases cramp was induced by the first afferent volleys; more often, however, continued stimulation produced stepwise recruitment of motor units (whose rhythmic firing was visible as myokymia in the muscle) until cramp developed. Cramps and myokymic discharges could usually be terminated by a single maximal stimulus to the motor axons (producing antidromic invasion and Renshaw inhibition of the motor neurons), or by short trains of volleys in inhibitory pathways from the skin. The fact that it was possible to induce myokymia and cramps by brief synaptic excitation and terminate them by antidromic invasion or synaptic inhibition, suggests that the mechanism generating these disturbances is intrinsic to alpha-motor neuron somata. Similar on-off switching of self-sustained motor discharges has been observed in the decerebrate cat and is known to depend on 'bistability' of the motor neuron membrane. We propose that a similar mechanism is responsible for discharges that produce cramp.- - - - - - - - - - ranking = 7keywords = myokymia (Clic here for more details about this article) |
4/6. Idiopathic generalized myokymia.Idiopathic generalized myokymia (IGM) is a rare, heterogeneous, and poorly understood syndrome. We present analysis of 75 reported cases in the world literature. IGM affects men and women equally, with a mean age of onset 29 /- 19 years. patients' common presenting complaints are stiffness (60%), cramps (12%), weakness (12%), and muscle twitching (4%). family history is positive in 30%. In addition to generalized clinical myokymia (92%), abnormal neurologic findings include: hyporeflexia (70%), weakness (45%), grip myotonia (39%), and calf hypertrophy (16%). Electrical activity consisting of spontaneous continuous motor unit activity and/or electrical myokymia was documented in all patients. When electrical myokymia was observed (66%), the grouped discharges where irregular and had an interburst frequency of 2-300 Hz. Both phenytoin and carbamazepine are effective treatments. We conclude that IGM has a wide spectrum of symptoms and severity and should be considered in all patients that present with stiffness, cramps, or muscle twitching. EMG greatly aids in diagnosis.- - - - - - - - - - ranking = 8keywords = myokymia (Clic here for more details about this article) |
5/6. Localized myokymia caused by peripheral nerve injury.One year after a gunshot wound in the popliteal fossa, a 30-year-old man began to experience cramps and myokymia in the left gastrocnemius muscle. myokymia was characterized by vermicular fibrillary movements localized to the gastrocnemius muscle and accompanied by plantarflexion and dorsiflexion of the toes. neurologic examination, nerve conduction velocities, electromyograms, and muscle biopsy findings showed affection of left common peroneal and posterior tibial nerves. The myokymia disappeared during sleep, spinal anesthesia, and treatment with carbamazepine.- - - - - - - - - - ranking = 6keywords = myokymia (Clic here for more details about this article) |
6/6. A case of myokymia-cramp syndrome successfully treated with gabapentin.We report a case of "myokymia-cramp syndrome", a rare and benign disease consisting of muscular cramps in the upper and lower limbs associated with generalized myokymias. In our patient, cramps had been present since adolescence and had increased in frequency and duration during the last 3 years, occurring about 8 or 9 times a day. Cramps were mainly nocturnal and also precipitated by walking; a previous treatment with carbamazepine did not improve the symptoms. Gabapentin therapy proved to be very satisfactory in relieving muscular cramps with a relatively low dosage (600 mg/day) and without any remarkable side effects. The possible interpretation of the mechanism involved in gabapentin induced relief of cramps is discussed. Gabapentin should be considered as a safe alternative treatment for muscular cramps.- - - - - - - - - - ranking = 6keywords = myokymia (Clic here for more details about this article) |