Abrupt onset of progressive muscular atrophy

Progressive muscular atrophy (PMA) refers to motor neuron disease (MND) presenting with weakness and wasting of muscles of the limbs and trunk without evidence of upper motor neuron lesion. The onset and progression are typically slow. We present a patient with PMA who had an abrupt presentation after heavy cocaine consumption and physical exercise. We are not aware of a similar case in the literature. A 40-year-old black male had spent the night dancing and consuming large amounts of cocaine (inhalation of approximately 8 grams) in September 1999. The following morning he decided to run 5 km to his home. Upon arrival he described sudden onset of generalised muscular pain, fasciculations and diffuse cramps. These symptoms persisted for two months and then progressively declined in intensity, but he noted slight proximal weakness in his right arm. There was a history of regular physical training and of occasional mild cocaine and cannabis consumption, but no history of alcohol or anabolic steroid intake, or of other medical disorders. He denied previous symptoms of cramp, fasciculations or weakness. On admission, in November 1999, we noted a man with an athletic body with good muscular development. He had abundant, widespread fasciculations in limb muscles, cramps easily precipitated by muscle contraction, and slight proximal weakness of the right arm, but no atrophy. There was generalised hyporeflexia, with flexor plantar responses, no sensory impairment, no cranial nerve abnormality, and no muscle pain on palpation. Blood tests revealed very high CK level (3500 i.u./L, normal 15–130), andmildly increased serum glutamic oxaloacetic transferase (SGOT) (90 i.u./L, normal 0–25) and serum glutamic-phosphoryl transferase (SGPT) (120 i.u./L, normal 0–29) levels. The following tests were normal or negative: blood cell count; sedimentation rate; renal function tests; glycaemia; serum and urine immune electrophoresis; thyroid function tests; serum concentration of vitamin B12, folic acid, cortisol, electrolytes and calcium; immunological screening, and serological tests to HIV I/II, HTLV I/II, hepatitis C virus, Epstein-Barr virus, echovirus, coxsackie virus, and to brucella, borrellia, toxoplasma, and treponema infection. Cerebrospinal fluid analysis was normal. Respiratory function tests and nocturnal oxymetry were normal. Cranial CT scan and spinal cord MRI showed no abnormality. Electromyography (EMG) showed normal motor and sensory studies (ulnar, peroneal, and sural nerves, bilaterally). Needle sampling revealed fasciculations, highfrequency repetitive discharges, fibrillation potentials, and reduced interference pattern, in both tibialis anterior and deltoid muscles, and in biceps brachii on the right side. Motor unit potentials (MUPs) were of normal morphology, in accordance with acute denervation. Left biceps brachii showed fasciculations. Left masseter, right sternocleidomastoid, and hand interosseous and vastus medialis were normal on both sides. Transcranial magnetic stimulation revealed normal values in all four limbs. An open muscle biopsy of left deltoid was performed a few days after the EMG study. Haematoxylin and eosin, and modified Gomori trichrome stains revealed widespread variation of fibre size with largegroup atrophy, but no signs of necrosis or inflammatory infiltrates. Myofibrillar adenosine triphosphatase (ATPase, 4.6 and 9.7), periodic acid Schiff, nicotine adenine dinucleotide tetrazolium reductase (NADH-tr) and myophosphorylase staining were normal. A diagnosis of the PMA variant of MND was made, and riluzole therapy (50mg bid) was initiated. CK value declined sharply over the following three months to 1000 i.u. /L. For the previous 3.5 years he has had slow progression of his clinical condition (Figure 1) leading to severe weakness, atrophy, and fasciculations of the limbs and trunk. Cranial innervated muscles retain normal force. Deep tendon reflexes are absent and plantar reflexes are flexor. Recent EMG Department of Neurology, Department of Medical Rehabilitation, Hospital de Santa Maria, Lisbon, Portugal, Faculty of Medicine, IMM, University of Lisbon, Portugal