Factors Related to Successful Energy Transmission of Focused Ultrasound through a Skull: A Study in Human Cadavers and Its Comparison with Clinical Experiences

OBJECTIVE: Although magnetic resonance guided focused ultrasound (MRgFUS) has been used as minimally invasive and effective neurosurgical treatment, it exhibits some limitations, mainly related to acoustic properties of the skull barrier. This study was undertaken to identify skull characteristics that contribute to optimal ultrasonic energy transmission for MRgFUS procedures. METHODS: For ex vivo skull experiments, various acoustic fields were measured under different conditions, using five non-embalmed cadaver skulls. For clinical skull analyses, brain computed tomography data of 46 patients who underwent MRgFUS ablations (18 unilateral thalamotomy, nine unilateral pallidotomy, and 19 bilateral capsulotomy) were retrospectively reviewed. Patients' skull factors and sonication parameters were comparatively analyzed with respect to the cadaveric skulls. RESULTS: Skull experiments identified three important factors related skull penetration of ultrasound, including skull density ratio (SDR), skull volume, and incidence angle of the acoustic rays against the skull surface. In clinical results, SDR and skull volume correlated with maximal temperature (Tmax) and energy requirement to achieve Tmax (p<0.05). In addition, considering the incidence angle determined by brain target location, less energy was required to reach Tmax in the central, rather than lateral targets particularly when compared between thalamotomy and capsulotomy (p<0.05). CONCLUSION: This study reconfirmed previously identified skull factors, including SDR and skull volume, for successful MRgFUS; it identified an additional factor, incidence angle of acoustic rays against the skull surface. To guarantee successful transcranial MRgFUS treatment without suffering these various skull issues, further technical improvements are required.

Factors Related to Successful Energy Transmission of Focused Ultrasound through a Skull: A Study in Human Cadavers and Its Comparison with Clinical Experiences

OBJECTIVE: Although magnetic resonance guided focused ultrasound (MRgFUS) has been used as minimally invasive and effective neurosurgical treatment, it exhibits some limitations, mainly related to acoustic properties of the skull barrier. This study was undertaken to identify skull characteristics that contribute to optimal ultrasonic energy transmission for MRgFUS procedures.METHODS: For ex vivo skull experiments, various acoustic fields were measured under different conditions, using five non-embalmed cadaver skulls. For clinical skull analyses, brain computed tomography data of 46 patients who underwent MRgFUS ablations (18 unilateral thalamotomy, nine unilateral pallidotomy, and 19 bilateral capsulotomy) were retrospectively reviewed. Patients' skull factors and sonication parameters were comparatively analyzed with respect to the cadaveric skulls.RESULTS: Skull experiments identified three important factors related skull penetration of ultrasound, including skull density ratio (SDR), skull volume, and incidence angle of the acoustic rays against the skull surface. In clinical results, SDR and skull volume correlated with maximal temperature (Tmax) and energy requirement to achieve Tmax (p<0.05). In addition, considering the incidence angle determined by brain target location, less energy was required to reach Tmax in the central, rather than lateral targets particularly when compared between thalamotomy and capsulotomy (p<0.05).CONCLUSION: This study reconfirmed previously identified skull factors, including SDR and skull volume, for successful MRgFUS; it identified an additional factor, incidence angle of acoustic rays against the skull surface. To guarantee successful transcranial MRgFUS treatment without suffering these various skull issues, further technical improvements are required.

The advances of Deep Brain Stimulation (DBS) for treatment of Parkinson's disease (PD)

Advanced Parkinson's disease (PD) is characterized by the presence of motor fluctuations, various degrees of dyskinesia, and disability with functional impact on daily living and independence. Therapeutic management aims to extend levodopa (L-DOPA) benefit while minimizing motor complications and includes, in selected cases, the implementation of drug infusion and surgical techniques. The concept of deep brain stimulation (DBS) for PD was introduced over 20 years ago, but our understanding of the nuances of this procedure continues to improve. This review aims to demonstrate the advances of DBS in the treatment of PD patients. (AU)

Off-line analysis of single-unit neuronal discharge in the globus pallidus region in Parkinson's disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The accuracy of microelectrode-guided localization can make the operation safe and effective, but only experienced neurosurgeons are capable of performing this operation. A good index to identify neuronal discharges between globus pallidus interna and globus pallidus externa is needed. The aim of this research was to establish a good and practical electrophysiologic index to distinguish neuronal discharge in the interior globus pallidus from neuronal discharge in the exterior globus pallidus region of the brain in Parkinson's disease. The effect of neurons having an atypical discharge on successful surgical localization was also quantitatively evaluated.</p><p><b>METHODS</b>The study included 30 patients with primary Parkinson's disease who underwent pallidotomy between September 2000 and October 2002. During each pallidotomy, the neuronal discharges in the pallidum and its vicinity were recorded. The recorded spikes were used to calculate the frequency, burst index, pause index, and pause ratio of the single-unit discharge. The interior and exterior globus pallidus regions were compared in terms of frequency, burst index, pause index, and pause ratio. The sensitivity, specificity, false-negative ratio, false-positive ratio, and accuracy of those indices were then evaluated.</p><p><b>RESULTS</b>The values of frequency, burst index, pause index, and pause ratio in the interior globus pallidus were (96 +/- 43) Hz, 2.31 +/- 1.81, 0.05 +/- 0.05, and 0.27 +/- 0.28, respectively, and in the exterior globus pallidus were (59 +/- 27) Hz, 0.88 +/- 0.63, 0.20 +/- 0.14, and 1.54 +/- 1.17, respectively. Use of the four indices to distinguish the two neuron types produced a sensitivity of 0.84, 0.78, 0.77, and 0.93 with a specificity of 0.64, 0.79, 0.88, and 0.87, respectively. The false-positive ratio was 0.36, 0.21, 0.12, and 0.13 and the false-negative ratio was 0.16, 0.22, 0.23, and 0.07 while the accuracy was 0.72, 0.79, 0.80, and 0.90, respectively.</p><p><b>CONCLUSIONS</b>Pause ratio is a relatively reliable index to distinguish neuronal discharges between the interior and exterior globus pallidus regions in Parkinson's disease. The effect of neurons with atypical discharge on the successful surgical localization would be reduced to 10% when the pause ratio is used as the index.</p>

The box-dimension-based localization of neuronal structures in pallidotomy for treatment of Parkinson's disease / 生物医学工程学杂志

Currently, the intraoperative location of microelectrode position in the globus pallidus is subjective and qualitative; it only depends on the experience of doctors during pallidotomy for the treatment of Parkinson's disease. The fractal characteristic of neuronal discharge signals is analyzed for target localization; the factor of box dimension is extracted from the microelectrode recordings for identifying the neuronal structures at the depth of microelectrode. New objective and quantitative targeting technique is presented by processing clinical microelelctrode recordings of Parkinson's disease. Through the validation of clinical data and the critical appraisal by experts, the targeting technique can be used for improving the accuracy of localization in neurosurgery.

Inter-Racial, Gender and Aging Influences in the Length of Anterior Commissure-Posterior Commissure Line

OBJECTIVE: The length of anterior-posterior commissure (AC-PC) in racial groups, age, gender of patients with deep brain stimulation (DBS) and pallidotomy were investigated. METHODS: From January 1996 to December 2003, 211 patients were treated with DBS and pallidotomy. There were 160 (76%) Caucasians, 35 (17%) Hispanics, 12 (5%) Asians and 4 Blacks (2%). There were 88 males and 52 females in DBS-surgery group and 44 males, 27 females in pallidotomy group. Mean age was 58 year-old. There were 19 males and 19 females and mean age was 54.7 years in the control group. Measurements were made on MRI and @Target software. RESULTS: The average AC-PC distance was 24.89 mm (range 32 to 19), which increased with aging until 75 years old in Caucasian and also increased with aging in Hispanic, but the AC-PC distance peaked at 45 years old in Hispanic. The order of AC-PC distance were 25.2+/-2 mm in Caucasian, 24.6+/-2.24 mm in Asian, 24.53 mm in Black, 23.6+/-1.98 mm in Hispanic. The average AC-PC distance in all groups was 24.22 mm in female who was mean age of 56.35, 25.28 mm in male who was mean age of 60.19 and 24.5+/-2 mm in control group that was excluded because of the difference of thickness of slice. According to multiple regression analysis, the AC-PC distance was significantly correlated with age, race, and gender. CONCLUSION: The AC-PC distance is significantly correlated with age, gender, and race. The atlas of functional stereotaxis would be depended on the variation of indivisual brain that can influenced by aging, gender, and race.

Method of localization of microelectrode in the globus pallidus during pallidotomy for Parkinson's disease / 生物医学工程学杂志

Intraoperative analysis of the position of microelectrode in the globus pallidus only depends on experiences and subjective interpretation of microeletrode recording discharge of neurons during pallidotomy for Parkinson's disease. In this paper is reported a method for objective localization of microeletrode during neurosurgery. This method uses the factor of interspike interval based on microelectrode recordings. It is effective for identifying the change of the globus pallidal organism along the microelectrode pathway and the departure or deviation of the needle-pathway. The classification is consistent with the anatomic structures and the results of neurosurgery. This method can be used as a guide in pallidotomy. Globus pallidus.

Bilateral Pallidotomy for Dystonia with Glutaric Aciduria Type 1

Glutaric aciduria type 1 is an inborn error of lysine, hydroxylysine, and tryptophan metabolism caused by deficiency of glutaryl-coenzyme A dehydrogenase. The disease often appears in infancy with encephalopathy episode that results in acute basal ganglia and white matter degeneration. The majority of patients develop a dystonic-dyskinetic syndrome. This reports 6year-old boy who had been done previous gastrostomy due to swallowing difficulty underwent bilateral pallidotomy with intraoperative electromyography(EMG) monitoring for disabling dystonia. Intraoperative EMG was used to assess stimulation thresholds required for capsular responses and muscle tone. Surface EMG electrodes were placed on the face and cricopharyngeal muscles. Exact target were directly modified according to MRI-visualized anatomy. EMG response was consistently seen prior to visual observation of muscle activity. The surgery improved dystonic symptoms without swallowing difficulty.

Clinical Outcomes of Simultaneous Bilateral Pallidotomy in Advanced Parkinson's Disease

OBJECTIVE: Pallidotomy is known to improve the symptoms of idiopathic Parkinson, s disease (PD), motor fluctuations and dyskinesia related to levodopa therapy. Previous studies reported significantly higher complication rates associated with bilateral pallidotomy than unilateral pallidotomy. The authors assess the safety and clinical outcomes of bilateral pallidotomy for advanced PD. METHODS: Simultaneous bilateral pallidotomy was performed in eight patients with advanced PD between January 1, 2001 and December 31, 2001. All patients underwent lesion making in posteroventral site of internal globus pallidus. The target was localized using macroelectrode stimulation and MRI guided stereotactic technique. The lesions were made by radiofrequency currents. RESULTS: Among eight cases, seven had severe disabling dyskinesias. Compared with baseline scores, the values of dyskinesia after surgery was significantly decreased (P<0.05) for up to 1 year. The mean score changed from 4.4+/-2.1 to 0.3+/-0.5. According to Unified Parkinson's Disease Rating Scale (UPDRS), the mean motor score in off period, which was 38.3+/-13.8 was significantly decreased for 6 months (P<0.05). The ADL (on/off) scores and motor "on" scores of UPDRS were unchanged or deteriorated to 12 months after surgery. There was no apparent adverse effect after surgery in all patients. Only transient mild dysphagia happened in one patient. CONCLUSION: Simultaneous bilateral pallidotomy in advanced PD appears to be effective and safe, particularly in reducing the dyskinesia; in our experience, the side effects are not as high as reported by other groups.

Application of Leksell Stereotactic Frame Using External Landmarks in Stereotactic Surgery

OBJECTIVE: This study is designed to evaluate the usefulness of the cutaneous external landmarks in the application of a Leksell stereotactic frame for functional stereotactic surgery. METHODS: Surgical procedures included thalamotomy in 12 and pallidotomy in 4. Thalamotomy and later pallidotomy were performed in one. In application of the Leksell stereotactic frame, the authors used the cutaneous external landmarks including: (1) the pupil and the external acoustic meatus in group I, (2) the pupil and the crus of the helix in group II, (3) the lateral canthus, the crus of the helix, and inferior crura of antihelix in group III. This procedure was done for obtaining magnetic resonance(MR) images showing anterior and posterior commissure in the same axial scan. The targets were Vim for thalamotomy and GPi for pallidotomy. RESULTS: All MR images in group I, II, and III showed anterior and posterior commissures in the same axial scans except for two patients (17.7%) in group I. The MRI coordinate was accurate to localize the target within 1mm of the difference from electrophysiologic target in 76% of the patients. After surgery, a significant improvement was noticed in tremor scale and global outcome scale (p0.05). Transient postoperative complications including motor aphasia and hemihypesthesia were noticed in one each, which returned normal in 3 months. CONCLUSION: The cutaneous external landmarks are of value in applying Leksell stereotactic frame for obtaining magnetic resonance images, essentially showing anterior and posterior commissure. This method is also useful in saving total operation time, making patients comfortable, as well as cost effectiveness.

Ascertainment of Clinical Usefulness of Neurosurgery Simulator(R) in Stereotactic & Functional Neurosurgery

OBJECTIVE: An usefulness and an accuracy of Neurosurgery Simulator(R)(NSS(R)) is evaluated for the clinical applications. The NSS(R) is a surgical planning tool for stereotactic and functional neurosurgery, recently developed in Korea. METHODS: Thirty-four surgical cases, performed with the NSS(R) from October 1999 to April 2002, were analyzed. The accuracy was examined by comparing the actual lesion with the planned target. The usefulness was discussed with time consuming factor and convenience for surgical steps. Results of surgical outcome were also reviewed. RESULTS: The precise coordinates of surgical target is directly acquired by designating an anatomical lesion on the magnetic resonance image with NSS(R) due to auto recognition algorithm of the fiducials on the MRI image. The correctness is confirmed again by examining the anatomical lesion with superimposing the Schaltenbrand-Wahren atlas on the image directly. Among eleven cases of the thalamotomy for tremors, five cases resulted in complete resolution, the remaining five patients showed significant reduction of tremors. Improvement of ADL and UPDRS was recorded in all 6 Parkinson's disease patients who had undergone pallidotomy. Seventy five percent of patient in pain and psychosurgery resulted in improvements. The NSS(R) achieved 100% accuracy in calculating stereotactic biopsy coordinates. There was no deviation in guiding surgical trajectory. There was no significant surgical complication. CONCLUSION: Stereotactic and functional neurosurgery performed with the assistance of the NSS(R) is relatively safe and accurate.

Magnetic Resonance Image Guided Unilateral Pallidotomy for Parkinson's Disease; Surgical Technique and Clinical Efficacy

OBJECTIVE: The authors present a clinical analysis to determine the clinical efficacy of unilateral palliotomy for Parkinson's disease without microelectrode recording procedure and to review the surgical technique, based on the anatomical landmark using magnetic resonance(MR) image. METHODS: Twenty-seven patients were retrospectively studied with extensive neurological examinations including Unified Parkinson's Disease Rating Scale(UPDRS) in 'levodopa-on and -off' tate before and at 6 and 12 months following MRI-guided pallidotomy. Lesion location was characterized using thin sliced MR image and measured on axial slice of TOF image. Lesion was performed with radiofrequency lesion generator. RESULTS: Final surgical target was 2.7+/-0.3mm in front of the intercommissural point, 4.0+/-1mm below the imtercommissural line, and 20.2+/-1.4mm lateral to the midline of the third ventricle. Significant improvements were observed in the total UPDRS scores and motor scores. And there was no significant postoperative complication and sequale except transient paresis(2 cases) and dysarthria(1 case). CONCLUSION: Steretotactic MR image guided pallidotomy with macrostimulation for the patients with Parkinson's disease is safe with minimal morbidity and significantly reduces the disabilities of Parkinson's disease.

Efficacy of Unilateral Pallidotomy for Parkinson's Diesease

OBJECTIVES: For Parkinsonian patients who had not reacted favorably on drug therapy are good candidate for ventroposterolateral pallidotomy, although not curative. We studied these patients after unilateral pallidotomy, to confirm the effectiveness and safety of this procedure. METHODS: We evaluated the 17 patients with idiopathic Parkinson's diesease who had undergone unilateral posteroventral pallidotomy. All patients responded to levodopa initially. Mean age was 55 years(38-75years), and mean duration of disease was 9.8 years(3-20years). Pre-and postoperative evaluation at 3 month intervals included Unified Parkinson's Disease Rating scale(UPDRS) scoring, Hoehn and Yahr(H and Y) staging, and neuropsychological examinations. RESULTS: Pallidotomy significantly improved parkinsonian symptom(tremor, rigidity, bradykinesia, dyskinesia, sensory symptom). Nine of 10 patients who showed dyskinesia preoperatively significant improvement. The mean dose of levodopa in 9 patients was lowered. The mean H and Y score and UPDRS score were improved in on and/or off time in 15 patients. Among patients who were not improved, one patient worsened, and the others showed no change. The mean overall UPDRS off score changed from 76 preoperatively to 44(33%) at 6 months and from 70 to 52(25%) at 1 year. Transient surgical morbidity was showen in four patients and included dysarthria, hypotonia and confusion. CONCLUSION: We conclude that pallidotomy is safe and effective in patients who have levodopa-reponsive parkinsonism with severe symptom fluctuation. Unilateral pallidotomy also considered helpful to ipsilateral symptom. Unilateral pallidotomy can improve all of parkinsonian's symptom and allow to reduce the levodopa medication. Most of patients show satisfactory results.

Pallidotomy Guided by MRI and Microrecording for Parkinson's Disease

OBJECTIVE: The exact position of the lesion during the pallidotomy is critical to obtain the clinical improvement of parkinson's disease without damage to surrounding structure. Ventriculogrphy, CT(computed tomograpy) or MRI(magnetic resonance imaging) have been used to determine the initial coordinates of stereotactic target for pallidotomy. The goal of this study was to determine whether microelectrode recording significantly improves the neurophysiologic localization of the target obtained from MRI. METHODS: Twenty patients were studied. They underwent a unilateral pallidotomy. Leksell frame was applied and T1 axial images parallel to the AC-PC(anterior commissure-posterior commissure) plane using a 1.5 Tesla MRI with 3mm slice thickness were obtained. Anteroposterior coordinate of target was chosen at 2mm in front of the midcommissural point and lateral coordinate between 19 and 22mm from the midline. The vertical coordinate was calculated on coronal slice using a fast spin echo inversion recovery sequence(FSEIR) related to the position of the choroidal fissure and ranged over 4-5mm below the AC-PC plane. Confirmation of the anatomical target was done on axial slices using the same FSEIR sequence. Microrecording was done at the pallidum contralateral to the symptomatic side using an electrode with a tip diameter of 1nm diameter tip and 1.1-1.4 mOhm impedance at 1000Hz. Electrophysiologic localization of the target was also confirmed intraoperatively by macrostimulation. RESULTS: Microrecording techniques were reliable to define the transition from the base of the pallidum which was characterized by the disappearance of spike activity and by the change of the audible background activity. Signals from high amplitude neurons firing at 200-400Hz were recorded in the pallidal base. X, Y and Z coordinates of target obtained from the MRI were within 1mm from the X, Y, Z coordinates obtained with microrecording in 16 patients (80%), 15 patients(75%), 10 patients(50%) respectively. The difference of Y coordinate between on MRI and on microrecording was 4mm in only one patient. CONCLUSION: The MRI was accurate to localize the target within 1mm of the error from microrecording target in 70% of the patients. 4mm discrepancy was observed only once. We conclude that MRI alone can be used to determine the target for pallidotomy in most patients. However, microrecording technique can still be extremely valuable in patents with aberrant anatomy or unusual MRI coordinates. We also consider physiologic confirmation of the target using macrostimulation to be mandatory in all cases.

Simultaneous Ipsilateral Posteroventral Pallidotomy and Ventrolateral Thalamotomy for Advanced Parkinson's Disease

Stereotactic thalamotomy has traditionally provided good relief of tremor for patients with intractable tremor dominant in Parkinson's disease. However bradykinesia, dyskinesia and rigidity are less reliably treated with this technique. Although posteroventral pallidotomy(PVP) can alleviate dyskinesias appendicular bradykinesia and rigidity, tremor may not be completely ameliorated. Between January 1993 and May 1997, the authors performed posteroventral pallidotomy(PVP) on 69 patients with Parkinson's disease who had bradikinesia, rigidity, drug induced dyskinesia and tremor. Of these patients who had only PVPs 17(25%) patients had severe tremor, 20(29%) patients moderate tremor and 32(46 %) patients mild or no tremor after the surgery. We have combined ventrolateral thalamotomy(VLT ) and PVP in 37 patients with moderate to severe tremor. Of the 37 patients, who had both PVP and VLT, 27(73%) patients showed good improvement, and fair improve-ment in 10(27%). Except for 6 cases with transient dysarthria we did not encounter any other operative complications from the ipsilateral combined PVP and VLT. The combination of the two procedures appear to provide excellent relief for the majority of symptoms in patients suffering from advanced Parkinsons disease with rigidity bradykinesia, dyskinesia and tremor.

Neuronal Laterality & Postoperative Changes of GABA+Glu. Activity by In Vivo 1H MRS

Object of this study was to to evaluate the laterality of local cerebral cellular metabolism in various locations of the brain related to the symptomatic side of patients with clinically diagnosed idiopathic Parkinson's disease (IPD) and to verify GABA-related pathophysiology in IPD by comparing postoperative changes in (GABA+Glutamate)/Cr ratio from patients with IPD after stereotactic pallidotomy and thalamotomy. Fourteen patients with IPD(10 males and 4 females: age range 39-67 years) participated in the study. The patients were classified into two disease subgroups, one for tremor dominant group(n=7, T group), and the other bradykinesia and rigidity dominant one(n=7, B&R group). For T group, stereotactic VL(Vop, Vim) thalamotomy and subthalamotomy was performed and for the B&R group, stereotactic posteroventrolateral pallidotomy was selected. In Vivo 1H MRS study was performed on a 1.5 T MRI/MRS system(GE Sigma Advantage, version 4.8) using STEAM sequence after water suppression with CHESS RF pulse and dephasing gradients. After peak areas of creatine/phosphocreatine(Cr), choline-containning compound(Cho), N-Acetyl Aspartate(NAA), r-aminobutyric acid, (GABA) and glutamate(Glu) were calculated and processed, the metabolic ratios of NAA/Cr, Cho/Cr, and (GABA+Glu)/Cr in three different locations were calculated and compared with clinical symptoms and its changes after surgery. For the neuronal laterality in patients with IPD, there was significant differences of NAA/Cr ratio between the right and left sides of substantia nigra, thalamus and pallidum(p=0.00170). The magnitude of difference in NAA/Cr ratios between right and left side were significantly larger in substantia nigra(p=0.0141). Compared to the normal control values(1.82+/-0.52 in ages 27-50, 1.71+/-0.54 in ages 51-70 years), the neuronal loss was generally observed in at least one of three locationsin all patients. Moreover, NAA/Cr ratio was substantially lower in ipsilateral than contralateral substantia nigra of the parkinsonian symptomatic side. For preoperative(GABA+Glu)/Cr ratios of thalamus contralateral to the symptomatic side compared to that of ipsilateral, it was significant larger in thalamus of B&R group and significant smaller in T group. In the pallidotomy group, there was significant increase in the operated pallidum, whereas significant decrease in (GABA+Glu)/Cr ratios were noted in the operated side thalamus. And in the thalamotomy group, there were significant increase in the operated thalamus, whereas in the operated side pallidum, significant decrease in (GABA+Glu)/Cr ratios were noted. Neuronal laterality, pallidal neuronal loss and postoperative changes in GABA activity in patients with IPD were demonstrated on the basis of NAA/Cr and (GABA+Glu)/Cr ratio by In Vivo 1H MRS. The neuronal laterality was detected in the substantia nigra of all the parkinsonian patient, and NAA/Cr ratios in unilateral and bilateral disease were consistently lower in ipsilateral than in contralateral substantia nigra of the Parkinsonian disease side. Our result suggests that there may be another ongoing pathological process of ipsilateral neuronal degeneration with contralateral dopaminergic neuronal loss. The result of neuronal loss in pallidum supports with the previous reports concerning striatal degeneration in IPD. Our results concerning postoperative changes of (GABA+Glu)/Cr ratio suggests that separate pathophysiologic mechanisms may be involved in the development of two dominant symptom groups of IPD. That is, for the B&R group, pallidal overinhibition to the thalamus by the GABA-ergic system as previously noted, but for T group, a process other than GABA inhibitory mechanism with or without it may be involved.

Propofol Anesthesia in Stereotactic Operation for Movement Disorders / 대한마취과학회지

BACKGROUND: Stereotactic thalamotomy and pallidotomy for Parkinson's disease or essential tremor have been performed under local anesthesia. But some neurosurgeons have been reluctant to utilize this technique because of patient discomfort and neurological complications. So we used the propofol that provides excellent sedation and rapid and smooth recovery of mental abilities with minimal side effects. METHODS: After the patients were placed into the Leksell's stereotactic frame, anesthesia was induced by continuous infusion of propofol at the rate of 150 mcg/kg/min and then maintained at the rate of 50 mcg/kg/min. We investigated the hemodynamic changes, ABGA, total dose of propofol, time to loss of consciousness, recovery time from the end of infusion to eyes opening and side effects. RESULTS: The blood pressure decreased significantly at infusion start 15 min and 30 min (p<0.05) and heart rate decreased significantly at infusion start 30 min (p<0.05). The PaCO2 increased significantly at infusion start 15 min and 30 min (p<0.05). Total dose of propofol was 202.4+/-59.8 mg, time to loss of consciousness was 13.0+/-4.4 min, recovery time was 9.0+/-4.7 min and side effects were pain on infusion (2 cases) and postoperative nausea (1 case). CONCLUSIONS: Stereotactic thalamotomy and pallidotomy for Parkinson's disease or essential tremor were performed by infusion of propofol with minimal side effects and no neurological complications.

Treatment of Parkinson's Disease by Streotactic Thalamotomy and Pallidotomy

The authors report the surgical results of thalamotomy and pallidotomy, performed at our hospital between 1983 and 1993 for the treatment of Parkinson's disease. The series included a retrospective analysis of 156 patients with this condition by stereotactic ventrolateral(VL) thalamotomy(126 patients, 138 thalamotomies) and posterolateral pallidotomy(30 patients, 30 pallidotomies). Each patient was followed up postoperatively, for one year. Among those who underwent the stereotactic VL thalamotomy, 136/138 procedures(99%) led to improvement of tremor, and 83/138(60%) resulted in reduced rigidity. Stereotactic posterolateral pallidotomy, led to improvement of bradykinesia after 27/30 procedures(90%), of rigidity after 22/30(73%) and of tremor after 13/30(43%). Drug-induced dyskinesia showed a 42% improvement in the thalamotomy series and a 93% improvement in the pallidotomy series; the difference between the two series was significant(p0.557). In addition, for groups with greater preoperative disability(Hoehn & Yahr staging, groups III and IV), improvement was more likely after pallidotomy than after thalamotomy. In the pallidotomy series, dysphasia was the only serious complication and this was seen after 20% of procedures. In the thalamotomy series, however, complications included hypotonia(24%), transient confusion(19%), transient dysphasia(11%), permanent dysarthria(7%), subjective numbness(4%) and epileptic seizure(3%). The authors believe that posterolateral pallidotomy is much more effective than VL thalamotomy for the control of Parkinsonian bradykinesia and rigidity, but that thalamotomy is still a useful surgical option for the control of Parkinsonian tremor.

Basic Estimation of Intracerebral Reference Points: Data Analysis from 169 Korean People

During thalamotomy, we have to use the various kinds of brain reference points. From 1989 to 1992, the authors performed streotactic thalamotomy or pallidotomy in 169 patients suffering from tremor. We measured and estimated the important intracerebral reference points. These data were very meaningful for stereotactic functional neurosurgery in the Korean medical community because it is obtained from Korean people. We have also estimated the average location of targets for tremor submission.