Bilateral simultaneous posteroventral pallidotomy for the treatment of Parkinson's disease: neuropsychological and neurological side effects

Abstract

The authors report the underestimated cognitive, mood, and behavioral complications in patients who have undergone bilateral contemporaneous pallidotomy, as seen in their early experience with functional neurosurgery for Parkinson's disease (PD) that is accompanied by severe motor fluctuations before pallidal stimulation. Four patients, not suffering from dementia, with advanced (Hoehn and Yahr Stages III-IV), medically untreatable PD featuring severe "on-off" fluctuations underwent bilateral contemporaneous posteroventral pallidotomy (PVP). All patients were evaluated according to the Core Assessment Program for Intracerebral Transplantations (CAPIT) protocol without positron emission tomography scans but with additional neuropsychological cognitive, mood, and behavior testing. For the first 3 to 6 months postoperatively, all patients showed a mean improvement of motor scores on the Unified Parkinson's Disease Rating Scale (UPDRS), in the best "on" (21%) and worst "off" (40%) UPDRS III motor subscale, a mean 30% improvement in the UPDRS II activities of daily living (ADL) subscore, and 60% on the UPDRS IV complications of treatment subscale. Dyskinesia disappeared almost completely, and the mean daily duration of the off 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 lability was found in this patient, but he did demonstrate severe bilateral postoperative pretarsal blepharospasm (apraxia of eyelid opening), which interfered with walking and which required treatment with high-dose subcutaneous injections of botulinum toxin. No patient showed visual field defects or hemiparesis, but postoperative depression, changes in personality, behavior, and executive functions were seen in two individuals. Postoperative abulia was reported by the family of one patient, who lost his preoperative aggressiveness and drive in terms of ADL, speech, business, family life, and hobbies, and became more sleepy and fatigued. One patient reported postoperative mental automatisms, such as compulsive mental counting, and circular thoughts and reasoning during off phases; postoperative depression was found in two patients. However, none of the patients demonstrated these symptoms during intraoperative microelectrode stimulation. These findings are compatible with previous reports on bilateral pallidal lesions. A progressive lowering of UPDRS subscores was seen after 12 months, consistent with the progression 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 corticobulbar dysfunction and apraxia of eyelid opening, in addition to previously described motor and visual field deficits, which make this surgery undesirable even though significant improvement in motor deficits can be achieved.

Changes induced by levodopa and subthalamic nucleus stimulation on parkinsonian speech

“…This side effect has been observed following lesions of the thalamus, 15,19,20,49 the pallidum, 16,17,30,50,51 and the STN. 14,18,31 In these cases, worsening of speech may be explained by the proximity of the corticobulbar fibers to surgical targets.…”

“…If akinesia is improved, then parkinsonian dysarthria might also be expected to improve. However, neither ablative surgeries 30,31 nor stimulation of the pallidum 32 result in any significant improvement in terms of speech. Regarding stimulation of the STN, beneficial effects on specific speech components have been observed, [33][34][35][36] such as phonation 33,34,36 and articulation.…”

Mirthful laughter induced by subthalamic nucleus stimulation

“…In contrast to the pre-levodopa era, bilateral pallidotomies are rarely performed today (Iacono et al, 1995;Laitinen, 1995;Hariz and DeSalles, 1997;Schuurman et al, 1997;Scott et al, 1998;Ghika et al, 1999). Bilateral lesions of the pallido±thalamo±cortical circuit in the pallidum (Hartmann von Monakow, 1959;Svennilson et al, 1960;Dubois et al, 1995;Ghika et al, 1999) can lead to a severe frontal dysexecutive syndrome.…”

Postoperative management of deep brain stimulation in Parkinson’s disease

“…This may explain why there are few reports of acute neuropsychiatric adverse effects of GPi DBS (Ghika et al, 1999). A ventrocaudal difference in stimulation effects has been described within the motor territory.…”