Parkinson Disease - Top 25

September 2010, Volume 113, Issue 3

Parkinson Disease: Top 25 Cited Articles

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Jamal M. Taha, Michele A. Janszen and Jacques Favre

Object. In published series of patients who undergo deep brain stimulation (DBS) of the thalamus the effects of unilateral stimulation on contralateral limb tremor have been reported. The authors detail their experience with bilateral thalamic DBS in the treatment of head, voice, and bilateral limb tremor and compare it with earlier studies of unilateral stimulation.

Methods. Twenty-three patients (six with Parkinson's disease, 15 with essential tremor, and two with multiple sclerosis) underwent 19 bilateral DBS procedures (nine staged, 10 simultaneous) and four procedures contralateral to thalamotomy to control tremor of the head in 10, voice in seven, and limbs in 20 patients. Limb tremor improvement was graded as follows: 4, no tremor; 3, stress-induced tremor; 2, functional improvement; 1, no functional improvement; and 0, persistent tremor. Improvement of head or voice tremor was graded as follows: 4, greater than 75%; 3, between 50% and 75%; 2, between 25% and 50%; 1, less than 25%; and 0, no improvement. The mean follow-up period was 10 months.

Twenty-two patients (96%) demonstrated improved tremor at the last follow-up review. Of 20 patients with bilateral limb tremor, 17 (85%) improved to Grades 3 and 4, two patients (10%) with multiple sclerosis improved to Grade 2, and one (5%) exhibited tremor recurrence 8 months later. Nine (90%) of 10 patients with severe head tremor improved to Grades 4 or 3. Six (86%) of seven patients with voice tremor improved to Grade 3. Seven patients (30%) developed dysarthria, and seven (30%) developed disequilibrium; symptoms reversed in the majority of patients after the stimulation parameters were changed. One patient (4%) developed mild memory decline. There were no deaths.

Conclusions. The following findings are reported: 1) bilateral thalamic DBS and stimulation contralateral to thalamotomy are safe; 2) staging the procedure does not reduce the risk of dysarthria or gait disequilibrium; and 3) head and voice tremor are primary indications for bilateral DBS.

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Joachim K. Krauss, J. Michael Desaloms, Eugene C. Lai, David E. King, Joseph Jankovic and Robert G. Grossman

✓ The authors report the postoperative magnetic resonance (MR) imaging findings in 36 patients with advanced Parkinson's disease who underwent unilateral microelectrode-guided posteroventral pallidotomy. The lesions were placed within 1 mm of the ventral border of the globus pallidus internus (GPi) to include pallidothalamic outflow pathways. Sequential MR studies were obtained within 1 to 3 days postoperatively and at 6-month follow-up examination. Thirty-four (94%) of the 36 patients enjoyed sustained moderate or marked improvement of their parkinsonian symptoms 6 months postoperatively. Transient side effects occurred in five patients (14%), but there were no persistent complications. The pallidal radiofrequency lesions were prolate spheroid shaped and were composed of three concentric zones in the early postoperative studies. The mean volume of the middle zone, corresponding to the area of hemorrhagic coagulation necrosis, was 44.4 ± 17.6 mm3; the mean lesion volume as defined by the outer zone, corresponding to perilesional edema, was 262.2 ± 111.6 mm3. Additional edema spreading to the internal capsule was noted in 32 of 34 cases and to the optic tract in 11 of 34 cases. In two patients small ischemic infarctions involving the corona radiata were found, and in one a venous infarction was detected. Ischemic infarction resulted in mild transient Broca's aphasia in one patient, but there was no detectable neurological deficit in the other two. The mean volume of late-phase (6 months) lesions was 22 ± 28.8 mm3. In three patients no lesion was identified despite sustained clinical improvement. The lesion was located in the posteroventral GPi in all cases except in one patient in whom it was confined to the GP externus (GPe). This 49-year-old woman did not experience sustained benefit. The authors found no consistent correlations between lesion size and location and clinical outcome as measured by a global outcome score, the Unified Parkinson's Disease Rating Scale motor, activities of daily living, and bradykinesia “off” scores or rating of dyskinesias. Lesioning of pallidal and subpallidal pathways may contribute to the sustained clinical benefit in this series. Magnetic resonance imaging analysis showed that intraoperative microelectrode recording facilitated accurate placement of the lesion in this critical area.

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Volker M. Tronnier, Wolfgang Fogel, Martin Kronenbuerger and Sarah Steinvorth

A resurgence of interest in the surgical treatment of Parkinson's disease (PD) came with the rediscovery of posteroventral pallidotomy by Laitinen in 1985. Laitinen's procedure improved most symptoms in drug-resistant PD, which engendered wide interest in the neurosurgical community. Another lesioning procedure, ventrolateral thalamotomy, has become a powerful alternative to stimulate the nucleus ventralis intermedius, producing high long-term success rates and low morbidity rates. Pallidal stimulation has not met with the same success. According to the literature pallidotomy improves the “on” symptoms of PD, such as dyskinesias, as well as the “off” symptoms, such as rigidity, bradykinesia, and on-off fluctuations. Pallidal stimulation improves bradykinesia and rigidity to a minor extent; however, its strength seems to be in improving levodopa-induced dyskinesias. Stimulation often produces an improvement in the hyper- or dyskinetic upper limbs, but increases the “freezing” phenomenon in the lower limbs at the same time. Considering the small increase in the patient's independence, the high costs of bilateral implants, and the difficulty most patients experience in handling the devices, the question arises as to whether bilateral pallidal stimulation is a real alternative to pallidotomy.

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Andres Lozano, William Hutchison, Zelma Kiss, Ronald Tasker, Karen Davis and Jonathan Dostrovsky

✓ Methods for localizing the posteroventral globus pallidus internus are described. The authors' techniques include the use of microelectrodes to record single-unit activity and to microstimulate in human pallidum and its surrounding structures. This technique allows a precise determination of the locations of characteristic cell types in sequential trajectories through the external and internal segments of the pallidum. The location of the optic tract can be determined from microstimulation-evoked visual sensations and recordings of flash-evoked potentials. In addition, microstimulation-evoked motor and sensory responses allow the internal capsule to be identified. The data collected using this technique are an important adjunct to selecting optimum sites to place electrocoagulation lesions for stereotactic posteroventral pallidotomy for refractory Parkinson's disease.