Diagnosis of nonorganic monoplegia with single-pulse transcranial magnetic stimulation.

Sir: Single-pulse transcranial magnetic stimulation (spTMS) is used in clinical practice to evaluate the integrity of the corticospinal tracts.1 Here, we describe how spTMS assisted in proving that a patient with plegia of an upper limb and ipsilateral ptosis was malingering. Case report.A 35-year-old woman was admitted to the neurology department in August 2007 due to plegia of the upper limb and ptosis on the right, which had been present for the previous 4 years but had worsened suddenly in the last 24 hours. Neurologic examination disclosed monoplegia (Medical Research Council power grade 0 on the right upper limb). There were no signs of spasticity or sensory deficits. Plantar responses were flexor. Right ptosis was present, but it was atypical, giving the impression of a voluntary contraction of the mimic muscles of the left, rather than that of a pyramidal lesion. Magnetic resonance imaging (MRI) of the brain and cervical spinal cord, nerve conduction studies, electromyogram, and lumbar puncture had been performed 3 times previously. The results were unremarkable. Repeat brain and cervical MRI were again normal. We therefore re-evaluated the patient, focusing on potential nonorganic causes of her clinical picture (hysteria or malingering). Indeed, the patient's husband reported that the symptoms had worsened several times, always in periods of family distress. Given this, we proceeded to spTMS evaluation. Single-pulse TMS was delivered with a Magstim Rapid-2 stimulator (Magstim Company Ltd., Whitland, United Kingdom). The hand motor cortex was targeted with a 70-mm figure-of-8 coil. Stimuli were delivered at 100% stimulator output. Motor-evoked potentials (MEPs) were recorded from the abductor digiti minimii (ADM) muscles bilaterally. The central motor conduction time (CMCT) was calculated as CMCT 14;= (MEP latency) 14;– 14;(peripheral conduction time). 1 The CMCT was within normal limits (right ADM 14;= 14;6.8 ms, left ADM 14;= 14;6.7 ms). During the examination, the patient was distressed by the fact that she was not accustomed to the procedure and did not know its diagnostic potential. She was also surprised by the movement of her right upper limb in response to the magnetic pulses, and she persistently questioned us as to the meaning of our findings. On the basis of the normal CMCT, we reassured her that things were much better than she thought so far, that her symptoms would improve, and that she could accelerate her recovery by cooperating with the attending physicians. During the following day, the patient's right upper limb was still plegic, yet the ptosis was disappearing during conversation and reappearing when she was relaxed. Furthermore, she announced to her husband that the spTMS evaluation indicated a grave prognosis, contrary to what we had told her. On the basis of this evidence, we diagnosed malingering (according to DSM-IV-TR criteria) and referred the patient to the psychiatry department for further evaluation. Single-pulse TMS is a relatively new technique that is not used frequently in everyday practice; thus, patients are unaccustomed to it. As a result, it can prove useful in the management of malingerers simulating corticospinal lesions by providing neurophysiologic evidence on the integrity of the corticospinal tracts and by producing effects that surprise the patients. Spyros N. Deftereos, M.D., Ph.D. Gregory N. Panagopoulos, M.D. Department of Neurology Dimitra D. Georgonikou, M.D. Department of Psychiatry Elyssaios C. Karageorgiou, M.D. Panagiota N. Kefalou, M.D. Clementine E. Karageorgiou, M.D., Ph.D. Department of Neurology, Athens General Hospital “G. Gennimatas”, Athens, Greece