Predicting final lesion characteristics during MR-guided focused ultrasound pallidotomy for treatment of Parkinson's disease.

OBJECTIVE: Magnetic resonance-guided focused ultrasound (MRgFUS) ablation of the globus pallidus interna (GPi) is being investigated for the treatment of advanced Parkinson's disease symptoms. However, GPi lesioning presents unique challenges due to the off-midline location of the target. Furthermore, it remains uncertain whether intraprocedural MR thermometry data can predict final lesion characteristics. METHODS: The authors first performed temperature simulations of GPi pallidotomy and compared the results with those of actual cases and the results of ventral intermediate nucleus (VIM) thalamotomy performed for essential tremor treatment. Next, thermometry data from 13 MRgFUS pallidotomy procedures performed at their institution were analyzed using 46°C, 48°C, 50°C, and 52°C temperature thresholds. The resulting thermal models were compared with resulting GPi lesions noted on postprocedure days 1 and 30. Finally, the treatment efficiency (energy per temperature rise) of pallidotomy was evaluated. RESULTS: The authors' modeled acoustic intensity maps correctly demonstrate the elongated, ellipsoid lesions noted during GPi pallidotomy. In treated patients, the 48°C temperature threshold maps most accurately predicted postprocedure day 1 lesion size, while no correlation was found for day 30 lesions. The average energy/temperature rise of pallidotomy was higher (612 J/°C) than what had been noted for VIM thalamotomy and varied with the patients' skull density ratios (SDRs). CONCLUSIONS: The authors' acoustic simulations accurately depicted the characteristics of thermal lesions encountered following MRgFUS pallidotomy. MR thermometry data can predict postprocedure day 1 GPi lesion characteristics using a 48°C threshold model. Finally, the lower treatment efficiency of pallidotomy may make GPi lesioning challenging in patients with a low SDR.

Combined Unilateral Posteroventral Pallidotomy and Ventral Intermediate Nucleus Thalamotomy in Tremor-Dominant Parkinson's Disease versus Posteroventral Pallidotomy Alone: A Prospective Comparative Study.

BACKGROUND: The optimum target in surgery for Parkinson's disease (PD) is still controversial, especially in patients with tremor-dominant PD. We aim to compare results in tremor-dominant patients undergoing pallidotomy vs. those undergoing simultaneous posteroventral pallidotomy (PVP) and ventral intermediate nucleus (VIM) thalamotomy. METHODS: Twenty-four patients with tremor-dominant PD were included in this study. Twelve patients received unilateral PVP contralateral to the most affected side. The other 12 patients received simultaneous unilateral PVP and VIM thalamotomy contralateral to the most affected side. Assessment of results in both groups was achieved using both UPDRS "off" motor scores and UPDRS rest tremor subscores. RESULTS: The mean UPDRS off motor score improved in the pallidotomy group from 61.3 preoperatively to 36.8 at 12 months. In the combined group, it improved from 59.6 to 35.2 at 12 months, with no statistically significant difference between both groups. On the other hand, while the mean tremor subscore in the pallidotomy group improved from a mean of 2.3-0.8, the tremors were abolished in all of the patients in the combined group except for 1 patient who showed slight infrequent tremors at 12 months. CONCLUSION: Patients with tremor-dominant PD achieve more improvement in tremor control after combined PVP and VIM thalamotomy.

The Pioneering and Unknown Stereotactic Approach of Roeder and Orthner from Göttingen. Part II: Long-Term Outcome and Postmortem Analysis of Bilateral Pallidotomy in the Pre-Levodopa Era.

Before the advent of levodopa, pallidotomy was initially the most effective treatment for Parkinson disease, but it was soon superseded by thalamotomy. It is widely unknown that, similar to Leksell, 2 neurologists from Göttingen, Orthner and Roeder, perpetuated pallidotomy against the mainstream of their time. Postmortem studies demonstrated that true posterior and ventral pallidoansotomy sparing the overwhelming mass of the pallidum was accomplished. This was due to a unique and individually tailored stereotactic technique even allowing bilateral staged pallidotomies. In 1962, the long-term effects (3-year follow-up on average) of the first 18 out of 36 patients with staged bilateral pallidotomies were reported in great detail. Meticulous descriptions of each case indicate long-term improvements in parkinsonian rigidity and associated pain, as well as posture, gait, and akinesia (e.g., improved repetitive movements and arm swinging). Alleviation of tremor was found to require larger lesions than needed for suppression of rigidity. No improvement in speech, drooling, or seborrhea was observed. By 1962, the team had operated 13 patients with postencephalitic oculogyric crises with remarkable results (mean follow-up: 5 years). They also described alleviation of nonparkinsonian hyperkinetic disorders (e.g., hemiballism and chorea) with pallidotomy. The reported rates for surgical mortality and other complications had been remarkably low, even if compared to those reported after the revival of pallidotomy by Laitinen in the post-levodopa era. This applies also to bilateral pallidotomy performed with a positive risk-benefit ratio that has remained unparalleled to date. The intricate history of pallidotomy for movement disorders is incomplete without an appreciation of the achievements of the Göttingen group.

The changing landscape of surgery for Parkinson's Disease.

Neurosurgical interventions have been used to treat PD for over a century. We examined the changing landscape of surgery for PD to appraise the value of various procedures in the context of advances in our understanding and technology. We assessed the number of articles published on neurosurgical procedures for PD over time as an albeit imprecise surrogate for their usage level. We identified over 8,000 publications associated with PD surgery. Over half the publications were on DBS. The field of DBS for PD showed a rapid rise in articles, but is now in a steady state. Thalamotomy and, to a lesser extent, pallidotomy follow a biphasic publication distribution with peaks approximately 30 years apart. Articles on gene therapy and transplantation experienced initial rapid rises and significant recent declines. Procedures using novel technologies, including gamma knife and focused ultrasound, are emerging, but are yet to have significant impact as measured by publication numbers. Pallidotomy and thalamotomy are prominent examples of procedures that were popular, declined, and re-emerged and redeclined. Transplantation and gene therapy have never broken into clinical practice. DBS overtook all procedures as the dominant surgical intervention and drove widespread use of surgery for PD. Notwithstanding, the number of DBS articles appears to have plateaued. As advances continue, emerging treatments may compete with DBS in the future. © 2017 International Parkinson and Movement Disorder Society.

Pallidotomy for Writer's Cramp after Failed Thalamotomy.

BACKGROUND/AIMS: Although many reports have confirmed the effects of stereotactic thalamotomy for writer's cramp, pallidotomy for writer's cramp is yet to be investigated. METHODS: After a 22-year-old woman with writer's cramp had undergone stereotactic thalamotomy twice, symptomatic relief was only temporary. Because her dystonic symptoms spread around the proximal part of the upper limb, she underwent unilateral pallidotomy 21 months after the second thalamotomy. RESULTS: Unilateral pallidotomy improved her dystonic symptoms without any adverse effects immediately after the surgery. During a follow-up observation of 1 year, no recurrent writer's cramp was observed. CONCLUSION: For writer's cramp, when symptoms cannot be improved by thalamotomy, pallidotomy may achieve an effective outcome.

Impact of parameters of radiofrequency coagulation on volume of stereotactic lesion in pallidotomy and thalamotomy.

BACKGROUND: One of the many reasons why lesional surgery for movement disorders has been more or less abandoned may have been the difficulty in predicting the shape and size of the stereotactic radiofrequency (RF) lesion. OBJECTIVES: To analyse the contribution of various RF coagulation parameters towards the volume of pallidotomies and thalamotomies. METHODS: The relationship between temperature of coagulation, length of coagulated area and duration of coagulation on the one hand, and lesion volume on the other was retrospectively evaluated. Lesion diameters were measured on stereotactic thin-slice CT and MRI scans, and volumes of lesions were calculated concerning 36 pallidotomies and 14 thalamotomies in 46 patients who were operated using the same RF generator and same RF electrode. RESULTS: The coagulation temperature, length of coagulated area and duration of coagulation were all correlated to the lesion volume. However, for a given length of coagulated area, the lesion´s size was most strongly influenced by the temperature. Despite this clear correlation, and the relatively homogenous coagulation parameters, the lesions' volumes were markedly scattered. CONCLUSIONS: The volume of the stereotactic RF lesions could be correlated with the coagulation parameters, especially the temperature, at a group level, but could not be predicted in individual patients based solely on the RF coagulation parameters.

Surgery for tardive dyskinesia.

Tardive dyskinesia (TD) is an often bothersome side effect of antipsychotic treatment. Medical treatment options are usually disappointing. A few single case reports have suggested some efficacy of lesionning surgery (i.e. pallidotomy or thalamotomy). A much greater number of series (including one controlled-study) have assessed the effects of deep brain stimulation applied to the internal globus pallidus. All of them have shown a marked improvement of motor symptoms without any major psychiatric side effects.

Surgery for Parkinson's disease improves disability but not impairment components of the UPDRS-II.

The Unified Parkinson's Disease Rating Scale (UPDRS) activities of daily living (ADL) items have been described as reflecting both disability (true ADL items) and impairment (rather than ADLs). As a result of combining these scores, UPDRS part II scores may not accurately reflect the impact of surgery on ADLs [Hariz G.M., Lindberg M., Hariz M.I., Bergenheim A.T. Does the ADL part of the unified Parkinson's disease rating scale measure ADL? An evaluation in patients after pallidotomy and thalamic deep brain stimulation. Mov Disord 2003;18:373-81.]. The goal of the present study was to assess the metric properties of the ADL section of the UPDRS in terms of its ability to measure surgical change. We tested the effects of unilateral pallidotomy (N=14) and bilateral subthalamic nucleus (STN) DBS (N=11) on both disability and impairment components of the UPDRS-II at uniform follow-up assessment periods of 6 months and 1 year, with a subset of pallidotomy patients (N=9) re-assessed at 2 years. Across the follow-up periods in both patient groups, items identified as best reflecting disability showed significant improvement from pre-surgical levels, whereas items representing impairment showed no overall change. Consistent with this, change in total ADL scores was tempered by the inclusion of the impairment items. Because the measurement of a patient's functional status is important in determining the effectiveness of an intervention, analysis of appropriate items from the UPDRS ADL section is imperative.

[Microeletrode guided stereotactic pallidotomy and pallido-thalamotomy for treatment of Parkinson's disease]. / Tratamiento de la enfermedad de Parkinson con palidotomía y palido-talamotomíaestereotáctica guiada por microelectrodos.

OBJECTIVE: Authors evaluated the therapeutic effect of the MRI and microelectrodeguided stereotactic pallido- and pallido-thalamotomy in 33 patients with Parkinson's disease (PD), whose symptoms were refractory to pharmacological therapy. MATERIAL AND METHODS: The patients were evaluated according to the internationally standardized rating scales (UPDRS part II, III, Schawb & England, Hoehn & Yahr, and Fahn) at six timepoints: before the operation, and 2 days, 3, 6, 9 and 12 months postoperatively. The patients were divided into 2 groups. Those in group A had relief of all main parkinsonian symptoms after pallidotomy including tremor. The patients in group B had no relief of tremor after pallidotomy. For them the pallidotomy was completed by thalamotomy in the same sitting, which had resulted in cessation of tremor. RESULTS: The following results were obtained by using the UPDRS part III: after pallidotomy "On state" mean: preoperative 51.2, postoperative at 2nd day 29.5 at 3, 6 and 9th month 26, and at 12th month 28.7. "Off state" mean: preoperative 64.3, postoperative at 2nd day 31.6, at 3, 6 and 9th month 26, and at 12th months 30.5. After pallidothalamotomy "On state" mean: preoperative 43.5, postoperative at 2nd day 27.9, at 3rd month 22.9, at 6th month 22.8, and at 9 and 12th month 24.5. "Off state" mean: preoperative 62.6, postoperative at 2nd day 38, at 3rd month 30, at 6th month 31,8 and at 9 and 12th month 33.8. CONCLUSIONS: For those patients, whose tremor was not successfully controlled by pallidotomy, the combined pallido-thalamotomy was effective. The clinical symptomps, according to the rating scales, improved significantly in both groups (student t: P<0.0001), but bilateral lesioning carried higher surgical morbidity.

Visualization and navigation system development and application for stereotactic deep-brain neurosurgeries.

We present the development of a visualization and navigation system and its application in pre-operative planning and intra-operative guidance of stereotactic deep-brain neurosurgical procedures for the treatment of Parkinson's disease, chronic pain, and essential tremor. This system incorporates a variety of standardized functional and anatomical information, and is capable of non-rigid registration, interactive manipulation, and processing of clinical image data. The integration of a digitized and segmented brain atlas, an electrophysiological database, and collections of final surgical targets from previous patients facilitates the delineation of surgical targets and surrounding structures, as well as functional borders. We conducted studies to compare the surgical target locations identified by an experienced stereotactic neurosurgeon using multiple electrophysiological exploratory trajectories with those located by a non-expert using this system on 70 thalamotomy, pallidotomy, thalamic deep-brain stimulation (DBS), and subthalamic nucleus (STN) DBS procedures. The average displacement between the surgical target locations in both groups was 1.95 +/- 0.86 mm, 1.83 +/- 1.07 mm, 1.88 +/- 0.89 mm and 1.61 +/- 0.67 mm for each category of surgeries, respectively, indicating the potential value of our system in stereotactic deep-brain neurosurgical procedures, and demonstrating its capability for accurate surgical target initiation.

[Stereotactic pallidotomy and thalamotomy in the treatment of primary dystonia]. / Leczenie dystonii pierwotnej stereotaktyczna palidotomia i talamotomia.

BACKGROUND AND PURPOSE: The goal of the study was to assess the results of the stereotactic pallidotomy and thalamotomy in the treatment of primary dystonia. MATERIAL AND METHODS: Thirty patients with primary dystonia underwent twenty-eight stereotactic pallidotomies and twenty two thalamotomies. The operations were based on the fused images of computed tomography and magnetic resonance imaging, and were verified by an intraoperative neurophysiological investigation. Neurological and neuropsychological assessments were performed before surgery and at 3 days, 3 and 6 months after the operation. The Mann-Whitney U test was used to find out statistic differences between subgroups and the Wilcoxon test to compare results between particular assessments. RESULTS: The statistic analysis showed postsurgical amelioration of the neurological state lasting at least 6 months. A better long-term outcome was revealed in the subgroup of pallidotomies vs. thalamotomies, in the subgroup with the onset of dystonia after the age of 35 vs. earlier onset, and in the subgroup of the focal and local dystonia vs. generalized dystonia. The statistically significant improvement was achieved at a depression level and the statistically significant deterioration was not stated in the mental status after the operations. A very low percentage of neurological complications after the operations was found in the study. CONCLUSIONS: The stereotactic pallidotomies and thalamotomies are effective and safe options in the treatment of the intractable cases of primary dystonia. Both resulted predominantly in contralateral improvement of motor functions. However, the results of pallidotomies are better than thalamotomies six months after the surgery. The improvement of the mood without cognitive deterioration was revealed in the neuropsychological tests after the operations. Only few, persistent and mild complications were ascertained in the study.

[The role of tremorometry in predicting the outcome of ablative surgeries]. / A tremorometria szerepe az ablatív mutétek eredményességének elorejelzésében.

Ablative neurosurgical interventions are widely used for the treatment of advanced Parkinson's disease. However, in some cases, the achieved result is temporary and repeat operation is necessary to obtain a permanent effect. By analyzing 30 ablative surgeries using comparative accelerometry, we looked for a biological marker predicting the efficiency. In 27 cases where clinical symptoms were permanently improved, a significant increase in rest tremor frequency was observed in addition to reduction in tremor intensity. In contrast, in those three cases where the clinical effect of the surgery was only temporary, the frequency of tremor remained unchanged despite of the transitory decrease in intensity. We thus hypothesize that postoperative change in frequency of tremor but not the intensity may predict the outcome of ablative treatments.