Acute motor axonal polyneuropathy after a cisatracurium infusion and concomitant corticosteroid therapy.

A 40-yr-old male was admitted to the intensive care unit following blunt chest trauma. He had multiple rib fractures, bilateral pneumothoraces, and acute respiratory failure requiring mechanical ventilation. Sedation was achieved with midazolam and morphine, and later with propofol. The patient was paralysed with a continuous infusion of cisatracurium 1.42-5.75 micro g kg(-1) min(-1). Methylprednisolone 125 mg i.v. every 12 h was also started. After discontinuation of the cisatracurium infusion 7 days later, the patient manifested a flaccid quadriplegia with absence of deep-tendon reflexes. No sensory deficits were observed. Electromyography (EMG), repetitive nerve stimulation testing, and single fibre EMG (SFEMG) were performed at regular intervals after stopping cisatracurium. Clinical symptoms and electrophysiological examinations supported the diagnosis of acute motor axonal polyneuropathy related to concomitant administration of cisatracurium and corticosteroid therapy.

Fetus-like dystrophin expression and other cytoskeletal protein abnormalities in centronuclear myopathies.

We have investigated supposed maturational arrest of muscle in centronuclear myopathies (CNMs) by characterizing the expression of dystrophin, other cytoskeletal proteins, and fetal myosin in the muscle fibers of 9 CNM patients (4 sporadic, 3 familial, 2 adult sporadic). Dystrophin and beta-spectrin localized intracytoplasmically in centrally nucleated fibers. Talin and vinculin were normally expressed. Desmin was radially organized in several fibers in all patients. Scattered vimentinpositive fibers were found in 3 cases. Six myotonic dystrophy cases and 4 inflammatory myopathy cases with regenerating fibers were also studied: dystrophin and the membrane cytoskeletal proteins were normally expressed in the former; and dystrophin, spectrin, and vinculin were reduced in the latter. Intracytoplasmic dystrophin is further evidence of maturational arrest in CNMs. Spectrin and dystrophin codistribute in these pathological conditions as in normal muscle. We conclude that the altered cytoskeletal network found in CNMs likely plays a pathogenetic role in these conditions.

Expression of cytoskeleton proteins in central core disease.

Despite advances in genetics the pathogenesis of central core disease (CCD) is still unknown. We studied muscles from 5 CCD patients by immunocytochemistry using monoclonal antibodies against various cytoskeletal proteins (dystrophin, spectrin, vinculin, desmin, vimentin, myosin heavy chain (MHC) of developmental, neonatal, adult slow and fast types). Dystrophin, spectrin and vinculin immunoreactivity was localized only at sarcolemma as in normal muscle. Vimentin was not present in myofibers. Only sporadic fibers were positive for developmental and neonatal MHC isoforms in adult CCD muscles. A 4-month-old patient had 5% of neonatal MHC-immunoreactive fibers, a finding similar to that of age-matched normal muscle. Desmin intermediate filaments were overexpressed in many core-fibers in extra-core regions, reduced or absent at cores, and greatly increased at the periphery of some cores. Moreover, irregular desmin-positive spots were seen within some cores. On the contrary, in neurogenic muscle atrophy patients, target lesions had increased desmin. These features indicate a possible role of desmin in the pathogenesis of cores, although we do not know if primary or secondary. In addition, they suggest that: (i) cores and targets may be manifestations of different processes; (ii) it is likely that core-fibers are not denervated fibers.

Muscle phosphoglycerate mutase (PGAM) deficiency in the first Caucasian patient: biochemistry, muscle culture and 31P-MR spectroscopy.

Muscle phosphoglycerate mutase (PGAM) deficiency has been so far identified in only six patients, five of these being African Americans. We report the results of clinical, morphological, biochemical, muscle culture and 31P-MR spectroscopy studies in the first Caucasian patient with muscle PGAM deficiency. A 23-year-old man had a 10-year history of cramps after physical exertion with one episode of pigmenturia. Neurological examination and EMG study were normal. ECG and echocardiography revealed hypertrophy of the interventricular septum and slight dilation of the left chambers of the heart. Muscle biopsy revealed increased glycogen content and some accumulation of mitochondria. Muscle PGAM activity was markedly decreased (6.5% and 9.7% of control value in two different biopsies). Citrate synthase and other mitochondrial respiratory chain enzyme activities were much higher than normal. In contrast to the marked decrease of PGAM activity observed in muscle biopsy, total enzyme activity in the patient's aneural muscle culture was normal, being represented exclusively by BB isoenzyme. The deficiency of PGAM-MM isoenzyme was reproduced in the patient's innervated muscle culture. Muscle 31P-MR spectroscopy showed accumulation of phosphomonoesters only on fast "glycolytic" exercise. On "aerobic" exercise, Vmax, calculated from the work-energy cost transfer function, showed an increase consistent with the morphological and biochemical evidence of mitochondrial proliferation. This might represent a sort of compensatory aerobic effort in an attempt to restore muscle power.

Muscle mitochondria investigation in myotonic dystrophy.

Mitochondrial abnormalities have been previously reported in some patients with myotonic dystrophy (DM). The aim of the present paper was to study muscle mitochondria in 32 DM patients by morphological, biochemical (when suggested by morphology) and genetic analysis. A single ragged red fiber, but no cytochrome c oxidase-negative fibers were found in the muscle specimen of 1 patient. However, mitochondrial enzyme activities resulted within the normal range. An electron microscopy study showed no significant mitochondrial changes. Southern blot analysis did not reveal any mitochondrial DNA heteroplasmy in all 32 patients. An explanation for the discordant results between this study and some previous reports of mitochondrial alterations in DM might be that their occasional presence is not related to the disease but to ageing. Another possibility is that among patients with a myotonic dystrophy phenotype, a small subgroup of subjects with a mitochondrial disease may exist and be differentiated.

Muscle rearrangement in patients with hemiparesis after stroke: an electrophysiological and morphological study.

Skeletal muscle changes were evaluated in patients suffering from hemiparesis after stroke. Concentric needle EMG and single fiber EMG of the paretic gastrocnemius medialis muscle were performed. Maximal amplitude of H, T and M responses in calf muscles of both the affected and the unaffected sides were determined by usual electrophysiological techniques. Muscle biopsy of the lateral gastrocnemius muscle of the affected side was performed to determine the distribution of fiber types and fiber sizes. Fibrillation activity and positive sharp waves occurred in paretic muscles in patients with more recent hemiparesis while the duration of motor unit potentials was prolonged in patients with long-lasting disease. The H/M ratio was increased on the paretic side. The percentage of type 1 fibers was augmented in most patients with normal mean diameter and low atrophy factor. The percentage of type 2 fibers was reduced with decreased mean diameters and with a high atrophy factor. Such changes may be related to inactivity or transsynaptic degeneration of type 2 motoneurons as a consequence of the interruption of the corticospinal tract. Increased percentage of type 1 fibers may be due to a collateral reinnervation process or a motor unit type transformation.

Peripheral neuropathy in amyotrophic chorea-acanthocytosis.

We investigated involvement of the peripheral nervous system in 6 patients with amyotrophic chorea-acanthocytosis. Electromyographic and neurographic findings, and pathological changes as demonstrated by examination of biopsy specimens of muscle and sural nerve indicate that most patients had an axonal sensorimotor polyneuropathy with more pronounced involvement of the distal portion of the nerves. Results obtained in one patient raised the question of an anterior horn cell disorder.

Adult-onset centronuclear myopathy: evidence against a neurogenic pathology.

A case of sporadic adult-onset centronuclear myopathy is presented. EMG was myopathic and nerve conduction study entirely normal. Single-fiber electromyography showed a normal percentage of potential pairs with abnormal jitter, slightly increased mean jitter value, no blocking and normal fiber density. Somatosensory and motor evoked potentials were within the normal limits. While it is still a subject of debate whether centronuclear myopathy is neuropathic or myopathic in origin, our findings are against peripheral nerve and CNS involvement.

Effect of ACTH4-10 on nerve fiber regeneration after sciatic nerve crush in rabbits: an electrophysiological and morphological study.

Crush of sciatic nerve in rabbits supported by morphologic and electrophysiologic data was used to evaluate the effects of ACTH4-10 on nerve fiber regeneration. Treated animals showed a statistically significant higher regeneration rate than did control rabbits. Fiber density and mean diameters of myelinated nerve fibers were measured in semithin nerve sections at 1 and 3 cm distal from the crushed point at three different time points. Nerve fiber density results were higher in ACTH4-10-than in vehicle-treated rabbits. This difference showed an unequivocal trend and attained a statistically significant level in the sections 3 cm distal from the crush. ACTH4-10 seemed therefore to have a beneficial effect on nerve fiber regeneration.