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.
Acoustics ; Brain ; Cadaver ; High-Intensity Focused Ultrasound Ablation ; Humans ; Incidence ; Pallidotomy ; Retrospective Studies ; Skull ; Sonication ; Ultrasonics ; Ultrasonography

BACKGROUNDThe 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.

METHODSThe 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.

RESULTSThe 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.

CONCLUSIONSPause 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.

Adult ; Electrophysiology ; Female ; Globus Pallidus ; metabolism ; Humans ; Male ; Microelectrodes ; Middle Aged ; Pallidotomy ; methods ; Parkinson Disease ; metabolism ; surgery

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.
Electrophysiology ; Globus Pallidus ; physiopathology ; surgery ; Humans ; Microelectrodes ; Neurons ; physiology ; Pallidotomy ; methods ; Parkinson Disease ; physiopathology ; surgery ; Stereotaxic Techniques ; Surgery, Computer-Assisted ; methods

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.
African Continental Ancestry Group ; Aging ; Asian Continental Ancestry Group ; Brain ; Continental Population Groups ; Deep Brain Stimulation ; Female ; Hispanic Americans ; Humans ; Male ; Pallidotomy

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.
Adult ; Aged ; Female ; Globus Pallidus ; surgery ; Humans ; Male ; Microelectrodes ; Middle Aged ; Pallidotomy ; methods ; Parkinson Disease ; surgery ; Stereotaxic Techniques ; Surgery, Computer-Assisted ; methods

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.
Basal Ganglia ; Deglutition ; Dystonia* ; Electrodes ; Gastrostomy ; Glutaryl-CoA Dehydrogenase ; Humans ; Hydroxylysine ; Lysine ; Male ; Metabolism ; Muscles ; Pallidotomy* ; Tryptophan

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.
Activities of Daily Living ; Deglutition Disorders ; Dyskinesias ; Globus Pallidus ; Humans ; Levodopa ; Magnetic Resonance Imaging ; Pallidotomy* ; Parkinson Disease* ; Stereotaxic Techniques

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.
Activities of Daily Living ; Biopsy ; Humans ; Korea ; Magnetic Resonance Imaging ; Neurosurgery* ; Pallidotomy ; Parkinson Disease ; Psychosurgery ; Tremor

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 (p<0.05), but not in total unified parkinson disease rating scale score and Hoehn and Yahr stage (p>0.05). 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.
Aphasia, Broca ; Cost-Benefit Analysis ; Ear Canal ; Humans ; Magnetic Resonance Imaging ; Pallidotomy ; Parkinson Disease ; Postoperative Complications ; Pupil ; Tremor

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.
Humans ; Microelectrodes ; Neurologic Examination ; Pallidotomy* ; Parkinson Disease* ; Postoperative Complications ; Retrospective Studies ; Third Ventricle