[Neuronopathy due to cisplatin]

Cisplatinum is a cytotoxic agent used in the treatment of different types of cancer. It often has side-effects, including a pure sensory syndrome with conservation of pain and temperature sense which is very disabling.

We present the case of a woman with cancer of the ovary and a man with oat cell carcinoma, who were treated with cisplatinum. After the course of chemotherapy was finished, with accumulated dosages of 500 mg/m2, they both developed paraesthesia of all four extremities, reduced control of fine movements and unstable gait. On physical examination there was distal hypoaesthesia with conservation of temperature and pain sensation, areflexia and sensory ataxia. The patient with ovarian cancer also had continuous pseudo athetotic movements. On neurophysiological studies, there was absence of peripheral and central sensory potentials and of H reflexes, normal electromyogram, normal motor conduction and normal mixed silent period.

The target organ in cisplatinum neurotoxicity has been identified, in experimental and human studies, as the dorsal root ganglion. Our patients had a syndrome which clinically and neurophysiologically suggested diffuse involvement of the dorsal ganglion (neuropathy) in which absence of sensory and H reflex potentials showed that the larger cells had been damaged. However, the normal mixed silent period suggested that the small myelinic cells were not altered, in accordance with the preservation of pain and temperature sensation.

We discuss the differential diagnosis between neuropathy due to cisplatinum and to paraneoplasia. We consider that there may be a tendency for certain heavy metals to damage posterior root ganglia.