Tactile illusion perception in patients with central pain.

Abstract

OBJECTIVE: To evaluate lemniscal pathways in patients with central pain (CP) by use of a novel tactile illusion (TI)-producing technique. PATIENTS AND METHODS: Somatosensory (SS) and TI testing was performed on the unaffected and affected wrists of 27 patients with unilateral central nervous system injury and unilateral CP. Data on TI testing-naive control subjects were used to adjust for a learning effect. RESULTS: Testing in CP patients with cervical and brainstem injuries revealed predominantly unchanged or decreased SS perception on the affected side compared with the unaffected side. The majority of cervical- and brainstem-injured subjects with CP had improved TI performance on the affected side compared with the unaffected side. All the thalamic-injured and most of the suprathalamic-injured CP patients had altered SS testing with either decreased or increased SS perception noted. In these same CP patients the majority had reduced TI perception on the affected side compared with the unaffected side. Unexpectedly, perseveration of numbers was noted in patients with Dejerine-Roussy syndrome, and expanded TI testing was performed to better define this observation. CONCLUSION: Cervical spinal cord-injured CP patients may have improved TI perception, whereas the majority of patients with supraspinal injuries and CP have reduced SS and TI perception. A unique sensory phenomenon of TI perseveration was observed in some patients with Dejerine-Roussy syndrome.