Joint and muscle pain with mononeuritis multiplex, tetraparesis, and myocardial infarction in a previously healthy adult

A 49 year old man presented with a three months' history of symmetrical joint and muscle pain, starting in the elbow region with further extension to the whole body, and weight loss of 11 kg within four months. Laboratory investigation showed an erythrocyte sedimentation rate (ESR) of 100 mm/1st h, leucocytosis of 20.6×109/l, and a massively raised rheumatoid factor. Creatine kinase (CK) and antineutrophil cytoplasmic antibodies (ANCA) were normal. The patient had pain in elbow, wrist, knee, and ankle regions, though no joint swelling was seen. Rheumatoid arthritis was suspected and treatment with steroids and methotrexate was started. Four weeks later, an ascending numbness of the extremities occurred, starting in the left foot and subsequently spreading to both lower legs and forearms. This was accompanied by a progressive muscle weakness. The patient was then referred to our institution. On admission, the patient presented with a temperature of 38.6°C, severely reduced general condition, blood pressure of 120/95 mm Hg, and a heart rate of 120 beats/min. He had gastric cramps after food intake and could not control bowel movements and urination owing to generalised weakness. Neurological examination showed severe pain on palpation of the proximal extremities and marked impairment of sensibility of the distal extremities as well as generalised hypo/areflexia. In addition, a distally accentuated, almost complete paralysis rendered the patient unable to lift his arms, legs, or head against gravity. Laboratory investigation at that time showed an ESR of 120 mm/1st h, CK of 1425 IU/l (normal <80 IU/l) with a muscle-brain isoenzyme (CK-MB) of 31 IU/l (normal <10 IU/l or less than 6% of total CK), rheumatoid factor of 719 IU/l, leucocytosis of 21.6×109/l with normal eosinophils, and a C reactive protein (CRP) of 306.3 mg/l. Complement levels were normal. Hepatitis B and C antibodies …