Bilateral contemporaneous posteroventral pallidotomy for the treatment of Parkinson's disease: neuropsychological and neurological side effects - Report of four cases and review of the literature

The authors report the underestimated cognitive, mood, and behavioral compl ications in patients who have undergone bilateral contemporaneous pallidoto my, as seen in their early experience with functional neurosurgery for Park inson's disease (PD) that is accompanied by severe motor fluctuations befor e pallidal stimulation. Four patients, not suffering from dementia, with advanced (Hoekn and Yahr S tages III-IV), medically untreatable PD featuring severe "on-off" fluctuati ons underwent bilateral contemporaneous posteroventral pallidotomy (PVP). A ll patients were evaluated according to the Core Assessment Program for Int racerebral Transplantations (CAPIT) protocol without positron emission tomo graphy scans but with additional neuropsychological cognitive, mood, and be havior testing. For the first 3 to 6 months postoperatively, all patients showed a mean imp rovement of motor scores on the Unified Parkinson's Disease Rating Scale (U PDRS), in the best "on" (21%) and worst "off" (40%) UPDRS III motor subscal e, a mean 30% improvement in the UPDRS II activities of daily living (ADL) subscore, and 60% on the UPDRS Iv complications of treatment subscale. Dysk inesia disappeared almost completely, and the mean daily duration of the of f time was reduced by an average of 60%. Despite these good results in the CAPIT scores, one patient experienced a partially regressive corticobulbar syndrome with dysphagia, dysarthria, and increased drooling. No emotional l ability was found in this patient, but he did demonstrate severe bilateral postoperative pretarsal blepharospasm (apraxia of eyelid opening), which in terfered with walking and which required treatment with high-dose subcutane ous injections of botulinum toxin. No patient showed visual field defects o r hemiparesis, but postoperative depression, changes in personality, behavi or, and executive functions were seen in two individuals. Postoperative abu lia was reported by the family of one patient, who lost his preoperative ag gressiveness and drive in terms of ADL, speech, business, family life, and hobbies, and became more sleepy and fatigued. One patient reported postoper ative mental automatisms, such as compulsive mental counting, and circular thoughts and reasoning during off phases; postoperative depression was foun d in two patients. However, none of the patients demonstrated these symptom s during intraoperative microelectrode stimulation. These findings are comp atible with previous reports on bilateral pallidal lesions. A progressive l owering of UPDRS subscores was seen after 12 months, consistent with the pr ogression of the disease. Bilateral simultaneous pallidotomy may be followed by emotional, behavioral , and cognitive deficits such as depression, obsessive-compulsive disorders , and loss of psychic autoactivation-abulia, as well as disabling corticobu lbar dysfunction and apraxia of eyelid opening, in addition to previously d escribed motor and visual field deficits, which make this surgery undesirab le even though significant improvement in motor deficits can be achieved.