Persistent unilateral tibialis anterior muscle hypertrophy with complex repetitive discharges and myalgia

Unilateral enlargement of the tibialis anterior muscle associated with complex repetitive discharges occurred over several months in two patients and was preceded by pain and numbness in the lower leg. Neuroradiologic investigations excluded a compressive radiculopathy, but pharmacologic and neurophysiologic studies suggested a neurogenic basis for the muscle hypertrophy. Botulinum toxin A injection into the hypertrophied muscles led to a decreased muscle volume and cessation of muscle pain.

Capillaries within human skeletal muscle fibers.

Internalized capillaries, i.e. capillaries within muscle fibers, represent a rare myopathological feature. This was systematically studied in 923 muscle biopsy specimens and found in 24, chiefly in the gastrocnemius muscle, more rarely in the biceps and quadriceps muscles affecting males more often than females and most frequently associated with juvenile spinal muscular atrophy or Becker's muscular dystrophy. Internalized capillaries, often multiple, ran along the long axis of the muscle fiber within an "internalized" extracellular space and were almost exclusively seen in type I myofibers. Internalization seems to start at the site of fiber splitting while penetration through the intact s…

Facial myokymia and contraction persisting 20 years: a case of pontine glioma.

Diabetic 3rd nerve palsy: evidence for a mesencephalic lesion.

Eleven consecutive adult chronic diabetic patients presented with an isolated 3rd nerve palsy (8 with pupillary sparing) of which 10 had abnormal ipsilateral or bilateral masseter reflexes (MassR). Three patients had an MRI lesion in the ipsilateral oculomotor fasciculus and 3 had subsequent mild brainstem signs. An additional 13 patients with Weber's syndrome had similar ipsilateral or bilateral MassR abnormalities, while 7 patients with 3rd nerve palsies on a known extra-axial basis had none. The findings suggest that an isolated diabetic 3rd nerve palsy, with or without pupillary sparing, is much more likely on the basis of a focal mesencephalic infarct than a peripheral nerve lesion.

Midbrain vs. pontine medial longitudinal fasciculus lesions: The utilization of masseter and blink reflexes

Masseter (MR) and blink reflexes (BL) were investigated in 51 patients with internuclear ophthalmoplegia (INO) due to multiple sclerosis (28) and lacunar infarction (23). The MR was abnormal in 20 of 23 cases with bilateral INO and in 21 of 28 with unilateral INO. The R1 component of the BL (BL-R1) was abnormal in 7 of 23 patients with bilateral INO and 10 of 28 with unilateral INO. Combined MR and BL-R1 changes occurred in 8 of 28 cases with unilateral INO and 7 of 23 with bilateral INO. The findings provide evidence for a rostral/caudal localization of lesions within the medial longitudinal fasciculus causing INO on the basis of MR and BL-R1 abnormalities. An abnormality limited to MR sug…

Ultrastructural pathology in emetine-induced myopathy

Progressive myopathy developed in two women who consumed ipecac syrup containing emetine hydrochloride to induce vomiting as part of their anorexia nervosa. Muscle biopsy specimens were characterized by severe disruption of the sarcomeres. The ultrastructural spectrum extended from "Z-band streaming" to the formation of cytoplasmic bodies and also comprised abnormalities of the sarcotubular system, thus suggesting that muscle weakness may be related to both sarcomeric and sarcotubular lesions in this self-inflicted myopathy. It is tempting to suggest that muscle weakness may be correlated with or based on the pathology in sarcomeres and the sarcotubular system. As the myopathy is clinically…

Impaired neuromuscular transmission during partial inhibition of acetycholinest-erase: The of stimulus-induced antiromic backfiring in the generation of the decrement-increment phenomenon

Neuromuscular transmission was studied in the rat phrenic nerve-hemidiaphragm preparation with acetylcholinesterase (AChE) partially inactivated. Enzyme inhibition resulted in (1) increased single-twitch tension of the diaphragm; (2) compound muscle action potential (CMAP) containing repetitive discharges; (3) stimulus-induced antidromic backfiring (SIAB) seen in the phrenic nerve; and (4) repetitive nerve stimulation (RNS) eliciting a decrement-increment (D-I) phenomenon (i.e., amplitude reduction maximal with the second CMAP). Using a high-calcium and low-magnesium solution, SIAB and the decrement of the second CMAP during RNS were intensified, whereas closely spaced trains and (+)-tubocu…

Efficacy of obidoxime in human organophosphorus poisoning: determination by neuromuscular transmission studies.

Six patients with organophosphorus compound intoxications developed an intermediate syndrome (weakness and fasciculations) and obidoxime was given on eight occasions. The efficacy of the acetylcholinesterase (AChE) reactivator was monitored electrophysiologically by neuromuscular transmission studies using single and repetitive nerve stimulation (20 and 50 Hz) and the activity of the serum (butyryl) cholinesterase (ChE). Dramatic electrophysiologic improvement was seen when obidoxime was given early within 12 h in 3 patients, although evidence of AChE inhibition did not subside completely. When administration of obidoxime was delayed 26 h or more after intoxication on five occasions, electr…

A quantitative study of the pancuronium antagonism at the motor endplate in human organophosphorus intoxication

Nine patients with organophosphorus (OP) intoxication developing neuromuscular transmission defects were given pancuronium 1, 2, or 4 mg intravenously (IV). Thirteen patient controls with hypoxic encephalopathy received similar dosages. The responses were monitored electrophysiologically using single and repetitive nerve stimulation (20 and 50 Hz). In OP patients, pancuronium did not alter the amplitude of the single CMAP, whereas its repetitive discharges were reduced. Severe neuromuscular blocks were reversed only partially by pancuronium 4 mg. In less severe blocks, 1 and 2 mg resulted in marked improvement. In the patient controls, pancuronium 4 mg induced a severe neuromuscular block b…

End-plate dysfunction in acute organophosphate intoxication.

Acute organophosphate intoxication resulting from suicide attempts in 14 patients produced a series of electrophysiologic abnormalities that correlated with the clinical course. Spontaneous repetitive firing of single evoked compound muscle action potentials (CMAP) was the earliest and most sensitive indicator of the acetylcholinesterase inhibition. A decrement of evoked CMAP following repetitive nerve stimulation was the most severe abnormality. At the height of the intoxication no CMAP was evoked after the first few stimuli. The decrement-increment phenomenon occurred only at milder stages of intoxication and its features are characteristic of acetylcholinesterase inhibition. These electr…

Internalized myofiber capillaries: Observations on their origin and clinical features

Internalized capillaries limited to type 1 muscle fibers were noted in seven patients. They occurred in each case in association with a similar admixture of neurogenic and myopathic features that included atrophic and hypertrophic fibers, internal nuclei, fiber splitting, and endomyseal and perimyseal fibrosis. Internalized capillaries in enlarged type 1 fibers arose from fiber splits on step section study of four patients. They occurred in the gastrocnemius, quadriceps, and soleus muscles from patients with a variety of disorders that included Becker dystrophy, diabetes mellitus and strenuous leg activities, Achilles tendon rupture, and myotonic dystrophy. Exercise-induced myalgias were no…

Pancuronium improves the neuromuscular transmission defect of human organophosphate intoxication.

Two patients with acute severe organophosphate intoxication showed (1) single evoked compound muscle action potentials (CMAP) with repetitive discharges and (2) prominent decremental responses of CMAP with 20 and 50 Hz supramaximal nerve stimulation. Following the intravenous injection of single small doses of pancuronium, marked improvement in these abnormalities occurred and persisted for several hours. We postulate that the physiologic improvement following low-dose pancuronium results from blockade of acetylcholine receptors, especially those located on the terminal axon responsible for antidromic backfiring.

Protective effect of serotonin on migraine attacks

Ultrastructure of the Retina in Adult Neuronal Ceroid Lipofuscinosis

A 33-year-old woman died of biopsy-proven adult neuronal ceroid lipofuscinosis (NCL) or Kufs’ disease marked by fingerprint and curvilinear lipopigments in neural and nonneural cell types. She had never experienced visual impairment or shown electroretinographic abnormalities. At autopsy, her retina appeared intact without degeneration at the light-microscopic level, but nerve cells in different layers were loaded with lipopigments of the granular type. This appears to be the third ultrastructural study of the retina in a patient with adult NCL, a former one showing preservation of the retina, another retinal degeneration. Thus, only further molecular genetic data will clarify the nosology …

Cerebrovascular Brainstem Diseases with Isolated Cranial Nerve Palsies

There is a significant number of individual patients with cranial nerve palsies as the sole manifestation of MRI- and, less frequently, CT-documented small brainstem infarctions or hemorrhages. The 3rd and 6th nerves are most commonly involved and, less frequently, the 4th, 5th, 7th, and 8th nerves. An intra-axial basis for such lesions may be underestimated if the diagnosis is based solely on MRI. The electrophysiologic abnormalities indicating brainstem lesions may be independent of MRI-documented morphological lesions. This paper reviews the literature on cerebrovascular brainstem diseases manifesting as isolated cranial nerve palsies. It supports the concept that small pontine and mesen…

High pancuronium sensitivity of axonal nicotinic-acetylcholine receptors in humans during organophosphate intoxication.

The effect of low-dose pancuronium on neuromuscular transmission was studied in 2 patients during the early and late stages of severe organophosphate intoxication. Single evoked compound muscle action potentials (CMAP) were followed by repetitive discharges and a decrement-increment (D-I) phenomenon with 10-, 20-, and 50-Hz supramaximal nerve stimulation. Intravenous pancuronium, 1 mg, abolished the D-I phenomenon, while the repetitive discharges of the CMAP were only partially reduced. It is postulated, that the disappearance of the D-I phenomenon with persistence of the CMAP repetitive discharges results from blockade of nicotinic-acetylcholine receptors located on the terminal axon respo…