Does the MMPI predict chemonucleolysis outcome?

Ninety-one patients with lumbar disc herniation were treated by chemonucleolysis with intradiscal chymopapain injection and evaluated at least 1 year after surgery (average, 18 months). There were 54 good, 10 fair, and 27 poor results after chemonucleolysis. Good versus fair/poor outcome groups differed preoperatively on the Minnesota Multiphasic Personality Inventory (MMPI) Hypochondriasis (Hs), Hysteria (Hy), Psychopathic Deviate (Pd), Paranoia (Pa), Hypomania (Ma), and Social Introversion (Si) scales. Presence of compensation issues at the time of surgery was significantly related to outcome, and the MMPI scales provided additional predictive power. Nineteen patients who did not show improvement with chemonucleolysis subsequently underwent lumbar laminectomy and discectomy, and the ultimate outcome for the entire series including these laminectomy patients was 66 good, 10 fair, and 15 poor results. Good versus fair/poor ultimate outcome patients differed significantly on preoperative MMPI Hypochondriasis, Hysteria, Psychopathic Deviate, Paranoia, Psychasthenia, Schizophrenia, Hypomania, and Social Introversion scales. After controlling for the effects of compensation issues, MMPI scales added significantly to the ability to predict ultimate surgical outcome. However, the MMPI could not be used with confidence to predict the outcome for a given patient and should serve only to alert the surgeon to the presence of psychological risk factors and the possible need for referral for psychological evaluation and treatment.