Multiple neuromuscular abnormalities in a paranoid schizophrenic

Myotoxicity and neurotoxicity during clozapine treatment

Some recent studies have shown that clozapine (CLZ) has myopathic side effects and causes alterations in motor force control. The aim of this study was to evaluate the neurologic and electrophysiologic characteristics of patients with schizophrenia who are undergoing long-term CLZ treatment. Ninety-four patients with schizophrenia treated with CLZ for 18.2 +/- 15.5 months were studied retrospectively and prospectively (40% and 60%, respectively) for serum creatine kinase (CK) levels before and after initiation of CLZ treatment. An electrodiagnostic study was performed on patients with CK elevation above normal limits, complained of general weakness or muscle pains, and/or had abnormal clinically significant findings. In 13 patients (13.8%), abnormal CK levels were found. Six patients complained of some muscular weakness. In two patients, clinical assessment revealed mild general muscular weakness; one revealed decreased tendon reflexes and, in both, CK levels were above 1,750 IU/L. On electrophysiologic examinations performed in the six patients with abnormal neurologic findings, the motor and sensory nerve conduction velocity were within normal range in all but one patient, who exhibited some prolongation of distal latency in the lower limbs. In two patients, the electromyography demonstrated a myopathic pattern. In 2.1% of medically healthy patients with schizophrenia treated with clozapine on a long-term basis, signs of myotoxicity were found. It seems warranted to discontinue CLZ therapy in patients who exhibit abnormal CK levels and myopathic features during treatment. Further studies are needed to provide more objective data on the impact of CLZ treatment on muscle tissue.

Muscle biopsy, macro EMG, and clinical characteristics in patients with schizophrenia

BACKGROUND

In a previous study of motor unit properties in patients with schizophrenia, muscle fiber histologic and electrophysiologic abnormalities were observed. The present study was designed to compare patients with schizophrenia with healthy control subjects with regard to muscle fiber histology and motor unit function. A second objective was to relate these variables to clinical characteristics.

METHODS

Twelve patients with first-episode schizophrenia and fifteen patients with chronic schizophrenia (DSM-III-R) and 27 matched control subjects were included in the study. Muscle biopsies were performed either in m. tibialis anterior or m. vastus lateralis. Electromyographic recordings (macro EMG) were made from the m. tibialis anterior motor units. Psychiatric ratings included the PANSS and extrapyramidal side effects.

RESULTS

Seven of the muscle biopsy specimens from the patients and one from the control subjects were classified as abnormal (p =.049). The most frequent abnormality was atrophic muscle fibers. Eight patients and no control subjects exhibited pathological macro EMG (p =.032). The findings were present in chronic as well as in first-episode patients with schizophrenia.

CONCLUSIONS

In approximately 50% of the patients, neuromuscular abnormalities were found either in the muscle biopsy or the macro EMG investigations. The results indicate that either a common pathologic process or different pathological processes are at hand in the neuromuscular system in patients with schizophrenia. The findings are compatible with a disturbed cell membrane function.

A study of motor dysfunction associated with schizophrenia based on analyses of movement-related cerebral potentials and motor conduction time

BACKGROUND

Several reports have shown that schizophrenics have motor dysfunction. The aim of this study was to identify the site of the nerve damage responsible for the motor dysfunction in schizophrenics by measuring both movement-related cerebral potentials (MRCPs) and motor conduction times.

METHODS

The subjects were 27 patients and 31 controls. There was no significant difference in age, nor in the length of the subjects' arms between the two groups. MRCPs were recorded during voluntary self-paced index movements of the thumb. The motor nerve conduction time was determined by magnetically stimulating the motor cortex and the spinal root.

RESULTS

Six of 27 schizophrenics had normal MRCPs, but the remaining 21 showed abnormal MRCPs. Of the 31 controls, 27 were normal, whereas 4 showed abnormal MRCPs. The difference between the two groups was significant; however, no significant differences were found in the motor conduction times, the motor root conduction times, or the central motor conduction times between the two groups.

CONCLUSIONS

Our results suggest that the responsible focus of motor nerve disorder in schizophrenia lies in the motor-integrating system in frontal lobe, and not in the nervous conduction system from the brain to the muscles.

Progressive catatonia

We present the case of a young man with a diagnosis of a childhood-onset pervasive developmental disorder who developed a progressive neurologic deterioration with persistent catatonia and right hemiparesis. On his initial evaluation approximately three years after the onset of mutism, he manifested right hemiparesis and catalepsy. Two years later, although catalepsy had subsided, motor function had deteriorated so that he could not use his hands to feed or dress himself. Oral-facialbuccal dyskinesia manifested by blepharospasm and grimacing were present constantly during waking hours. Quantitative electroencephalography demonstrated markedly decreased amplitude, a finding associated with catatonia. Left sural nerve biopsy indicated large axon cylinder degeneration. Left deltoid biopsy demonstrated perimysial fibrosis and type II fiber predominance. Although magnetic resonance imaging of the head without contrast was normal, positron emission tomography indicated hypometabolism of the right cerebral and the right cerebellar hemispheres. The patient continues to deteriorate despite a course of 25 electroconvulsive treatments. He continues to manifest criteria for catatonia including motoric immobility, mutism, and peculiarities of voluntary movement such as prominent grimacing. We suspect an inherited neurodegenerative disorder. Since catatonia is a treatable condition frequently associated with medical and neurological diseases, examination for the features of catatonia must be included in the assessment of patients with progressive brain degeneration. This report is an attempt to clarify the traits of a serious variant of progressive brain degeneration.

Schizophrenia and amyotrophic lateral sclerosis

Schizophrenia and amyotrophic lateral sclerosis (ALS) are central nervous system (CNS) disorders of unknown etiology. The association of these two disorders has been infrequently reported in the literature, but is not a rare occurrence. Various neuromuscular abnormalities involving the alpha-motor neuron have been described in some patients with schizophrenia. This report reviews the literature on schizophrenia, psychosis, and ALS and describes two additional cases of schizophrenia associated with ALS. The possibility that the neuromuscular dysfunction in schizophrenia may predispose to ALS and provide an explanation for the association of these two disorders is discussed. Additional research data are needed to test this hypothesis.

Muscle biopsy findings, conduction velocity and refractory period of single motor nerve fibres in schizophrenia

Eight untreated and eight neuroleptic treated male schizophrenic patients were studied. Light and electron microscopical analysis of muscle biopsies from the anterior tibial muscle showed a spectrum of pathological changes without significant quantitative or qualitative differences between the two groups. The changes included atrophic fibres, central nuclei, "moth-eaten fibres", "ring fibres", fibre splitting and subsarcolemmal and intermyofibrillar glycogen droplets. Electrophysiological investigation of single motor unit properties showed impaired peripheral impulse propagation in both patient groups while the conduction velocity and the refractory period of single motor nerve fibres were within the same range as in healthy subjects. In conclusion there are neuromuscular abnormalities in schizophrenic patients which cannot be attributed to medication or drug abuse.