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Robert P. Iacono, M.D., Jonathan D. Carlson, B.S.E., Sandra Kuniyoshi, B.A., Aymen Mohamed, M.D., Christine Meltzer, B.A., and Shokei Yamada, M.D.
Departments of Neurosurgery, Physiology, and Psychology, Loma Linda University Medical Center, Loma Linda, California
To investigate the effects of bilateral posteroventral pallidotomy (PVP) for Parkinson's disease (PD), the authors reviewed the technique and neurological outcome in a number of patients who had undergone bilateral pallidotomy. The authors have previously reported the outcome of PVP in 25 bilateral and 25 unilateral surgeries, rating the patient's postural stability, speech, and total Unified Parkinson's Disease Rating Scale scores. A second, separate group of 23 patients who underwent contemporaneous bilateral PVP were evaluated for early onset idiopathic PD, levodopa failure syndrome, and severe bilateral dyskinesia as well as akinetic "off" states. Cognitive and psychological studies were reviewed in 10 patients who demonstrated preoperative impairments in spatial recognition and memory. Following surgery there were significant improvements in these cognitive deficits and no deficits were incurred by surgery.
Published reports regarding bilateral operations for PD have emphasized the risks of speech and cognitive deficits. This study shows bilateral PVP to be effective, particularly in patients with bilateral symptoms, including disabling dyskinesia. Additionally, bilateral PVP does not cause additional cognitive or speech deficits. The techniques and indications as well as outcomes and complications are presented and discussed in this report in light of their controversial nature.
Key Words * bilateral pallidotomy * speech * cognition * Parkinson's disease
Although surgical interventions for Parkinson's disease (PD) are becoming accepted for alleviating tremor, hyperkinesias, and more recently akinesia, there are still controversies concerning the safety and indications for bilateral posteroventral pallidotomy (PVP). Other considerations in these procedures include the safety of contemporaneous versus staged bilateral surgery, the most effective targeting technique, indications, complications, and long-term outcome. These issues will be discussed, with a focus on deficits and complications reported to be associated with bilateral PVP.
CONTEMPORANEOUS BILATERAL PVP
Our early experience performing PVP focused on creating unilateral or staged bilateral lesions because of the well-known hazards of creating simultaneous symmetrical deep brain lesions, particularly associated with bilateral thalamotomy.[4] We soon realized that nearly all patients with symmetric or severe appendicular symptoms were requesting a second procedure for the alleviation of persistent symptoms on the unoperated side. As we gained experience in the creation of a second, staged lesion, we discovered that no significant ill effects from staged bilateral lesions occurred, particularly in speech or cognitive function. We progressively shortened the time interval between the operations until we saw no further benefit in delaying the second procedure. Now a large portion of the procedures we perform are contemporaneous bilateral PVP.[15]
INDICATIONS FOR CONTEMPORANEOUS PVP
Not all patients with parkinsonian symptoms are candidates for surgery, and an even smaller subgroup are candidates for bilateral surgery. Patients with "Parkinson's plus" symptoms, such as progressive supranuclear palsy, Shy-Drager syndrome, olivopontocerebellar atrophy, and normal-pressure hydrocephalus, should not be candidates for unilateral, much less bilateral, pallidotomy because of the structural and pathophysiological differences from idiopathic PD.
We have performed surgery in a wide range of patients with idiopathic PD, ranging in age from 31 to 85 years, with severity scores measured on the Hoehn and Yahr[26] scale of 1.5/1.5 to 5.0/5.0 on and off medication. Unilateral pallidotomy alone or combined with nucleus ventralis intermedius thalamotomy is performed in patients with dominant symptoms of asymmetrical tremor.[30] Contemporaneous bilateral PVP should only be attempted in patients with severe, symmetric, bilateral, hyperkinetic appendicular disabilities including dyskinesia, who are younger than 70 years old, and who are in a psychological state such that full informed consent and cooperation can be obtained. The most common parkinsonian subgroup meeting these criteria for contemporaneous bilateral PVP are the young onset or Narabayashi's[28] so-called "juvenile" PD patient, whose age at onset is younger than 45 years old. These patients usually progress rapidly to bilateral symptoms including disabling levodopa-induced dyskinesias, as well as severe and precipitous "off" states after 5 or more years of treatment.[3,9,10,27] The medical control of the dyskinetic symptoms in these patients is not often successful because essential dopaminergic medications cause disabling dyskinesia. The decrease in dosage of these medications is usually not an option because it results in profound "off" states and severe akinetic symptoms. Bilateral PVP affords impressive elimination of all appendicular and truncal dyskinesias, dystonia, and generally precludes the development of profound "off" states, thus eliminating levodopa failure syndrome in the patients. If only a unilateral pallidotomy is performed, most of these juvenile-type patients return for surgery on the second side because of the remaining hyperkinetic symptoms, even though the majority of their quality-of-lifetype parkinsonian symptoms have been alleviated.
TECHNIQUE IN PVP
Surgical techniques should be evaluated by their effectiveness, as measured by clinical outcome, reproducibility, complications, and, in this case, surgical precision. Although pr>