Tactile illusion perception in patients with central pain

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 th e unaffected and affected wrists of 27 patients with unilateral central ner vous system injury and unilateral CP, Data on TI testing-naive control subj ects were used to adjust for a learning effect. Results: Testing in CP patients with cervical and brainstem injuries reveal ed 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 c ompared with the unaffected side. All the thalamic-injured and most of the suprathalamic-injured CP patients had altered SS testing with either decrea sed or increased SS perception noted. In these same CP patients the majorit y had reduced TI perception on the affected side compared with the unaffect ed side. Unexpectedly, perseveration of numbers was noted in patients with Dejerine-Roussy syndrome, and expanded TI testing was performed to better d efine this observation, Conclusion: Cervical spinal cord-injured CP patients may have improved TI p erception, whereas the majority of patients with supraspinal injuries and C P have reduced SS and TI perception. A unique sensory phenomenon of TI pers everation was observed in some patients,vith DejerineRoussy syndrome.