Stereotactic Thalamotomy Research Articles

Intracranial ablative surgery in the treatment of chronic pain

This article reviews the historical and current options available for the intracranial ablative neurosurgical treatment of pain. For the current procedures (including nucleus caudalis DREZotomy, stereotactic mesencephalic tractotomy, medial thalamotomy, and cingulotomy), the authors review recent studies on effectiveness and complication rates. The authors also refer to their own personal experience with some of these procedures.

Identification and localization of intracerebral vessels by microvascular doppler in stereotactic pallidotomy and thalamotomy: technical note.

To identify intracerebral vessels in proximity to the target for thermocoagulation in functional neurosurgery, we use a microvascular doppler sensor held in a special supporting needle that fits in the straightening cannula for the thermocoagulation needle. After insertion of the straightening cannula aimed at the stereotactic target, the microvascular doppler probe positioned at the tip of a supporting hollow needle is advanced through the cannula. The proximal micrometer gauge indicates the depth of the tip of the doppler probe. By setting the doppler device to the shortest focusing depth (0.1 mm), the maximum pulsatile vascular sound indicates the depth of the vessel. A prominent vascular sound was identified in 3 of 13 cases. By adjusting the depth of the target, no major bleeding was experienced after thermocoagulation lesions were made. This technique secures and protects the fragile microvascular doppler and identifies any significant arterial vessels at the stereotactic target, thus avoiding vascular injury.

Stereotactic thalamotomy in tremor-dominant Parkinson's disease: an H2(15)O PET motor activation study.

Stereotactic thalamotomy is an effective treatment for severe drug-resistant tremor. The thalamus, however, facilitates motor activity, and thalamotomy would be predicted to inhibit movement-associated cortical activation. Two tremulous parkinsonian patients were studied with H2(15)O positron emission tomography before and after left ventralis intermedius thalamotomy. Subjects were scanned at rest and during performance of externally paced joystick movements in freely selected directions with the right hand. Thalamotomy relieved tremor but, as predicted, led to decreased activation of the left sensorimotor cortex, lateral premotor cortex, and parietal area 7 on hand movement.

MRI-guided stereotactic thalamotomy for cerebral palsy patients with mixed dyskinesia.

The author has performed 108 stereotactic thalamotomies using MRI (MGSTs) without ventriculography in 77 cerebral palsy (CP) patients with dyskinesia(s) from January 1992 to January 1997. The clinical results were verified in terms of improvement of major preoperative symptom and patient's (or relative's) satisfaction using pre- and postoperative video recording and simple questionnaires. The results were as follows: excellent in 12 MGSTs, good in 69 and fair in 27. Postoperative morbidity was transient in all patients except for 2. Recurrences were noted in 6 MGSTs (5.6%). There was no death. MGST is thus a beneficial procedure for reducing dyskinetic symptom(s) of CP patients.

Improvement of severe postural cerebellar tremor in multiple sclerosis by chronic thalamic stimulation

Tremor can be particularly disabling in patients with multiple sclerosis (MS) and is mildly improved by drug treatment. The efficiency of stereotactic thalamotomy has been reported in a small number of patients but was counterbalanced by severe postoperative complications. Stimulation of the thalamic ventral intermediate nucleus, which is a less aggressive surgical method, is efficient in essential and in parkinsonian tremors. We report here the results of thalamic stimulation in 13 patients with MS with tremor. All patients were subjected to clinical examination, videorecording, and quantification of the functional disability before surgery and 3 months postoperatively. The surgical intervention was well tolerated in all cases. A clear improvement of the tremor was observed in 69.2% of the patients. Functional improvement was more varied and depended on the severity of tremor and coexistence of other neurological symptoms. Of the eight most severely affected patients, seven recovered the possibility to easily catch an object and use it. The results indicate that thalamic stimulation may be useful in the treatment of severe postural cerebellar tremor in MS.

Disapperance of essential tremor after small thalamic hemorrhage

Stereotactic thalamotomy has been reported to be effective in the control of various tremors, including essential tremor. We report a 69-year-old female who experienced spontaneous thalamotomy with a small thalamic hemorrhage, resulting in disappearance of essential tremor on the contralateral side to the hematoma, which involved the nucleus ventralis intermedius (Vim) of the thalamus and a portion of the posterior limb of the internal capsule.

Stereotactic Gamma Thalamotomy for the Treatment of Parkinsonism

From September 1994 to June 1995, eight patients with intractable parkinsonism underwent gamma thalamotomy in our hospital. All of these patients were male, with an average age of 59.3 years. The duration of the disease from initial diagnosis was 2-10 years (mean 6.8 years). All had failed or had serious side effects with antiparkinsonian medicine. Seven cases had tremor-dominant symptoms, while the other had mainly rigidity. Six cases had bilateral symptoms. Computed tomography or magnetic resonance imaging (MRI) was undertaken prior to treatment in all cases to exclude focal brain lesions. Stereotactic MRI was taken with the Leksell frame in place and both T1- and T2-weighted images were obtained. The targets were located in the area of Vim/Voa/Vop based on the Schaltenbrand atlas. In seven cases, two plugged 4-mm-collimator shots were used. The maximum dose was 160 Gy in six cases and 180 Gy in one case. In another case, a single 4-mm-collimator shot was used, and a maximum dose of 160 Gy was delivered to the target center. The border of the internal capsule was outside the 20-30% isodose line. We intended the 50% isodose line to have an oval-shaped region with the use of two shots and should correspond to the shape of Vim. Follow-up data were available for six patients (mean: 4.5 months, range: 2-9 months). Tremor disappeared in three cases and improved in the other three. In one of these six cases, the tremor disappeared just 3 days after gamma thalamotomy. Rigidity improved in four of these six cases. In only one patient, treated with a maximum dose of 180 Gy, was there any contralateral limb weakness, which developed 3 months after treatment and has been recovering gradually. Follow-up MRI T2-weighted images in this case showed that the diameter of the lesion was larger than intended and there was a region of diffuse edema in the thalamus and upper brain stem. No other complications occurred in this series.

Low-threshold calcium spike bursts in the human thalamus. Common physiopathology for sensory, motor and limbic positive symptoms.

Positive symptoms arise after lesions of the nervous system. They include neurogenic pain, tinnitus, abnormal movements, epilepsy and certain neuropsychiatric disorders. Stereotactic medial thalamotomies were performed on 104 patients with chronic therapy-resistant positive symptoms. Peroperative recordings of 2012 single units revealed an overwhelming unresponsiveness (99%) to sensory stimuli or motor activation. Among these unresponsive cells, 45.1% presented a rhythmic or random bursting activity. Rhythmic bursting activities had an average interburst interval of 263 +/- 46 ms corresponding to a frequency of 3.8 +/- 0.7 Hz. Frequency variations among the different symptoms were not statistically different. Intraburst characteristics such as the highest frequency encountered in the burst (480 +/- 80 Hz) or the mean frequency of the burst (206 +/- 44 Hz) were also similar in all patients. All bursts, rhythmic or random, fulfilled the extracellular criteria of low-threshold calcium spike (LTS) bursts. After medial thalamotomy and depending on the symptom, 43-67% of the patients reached a 50-100% relief, with sparing of all neurological functions. On the basis of these electrophysiological and clinical results, we propose a unified concept for all positive symptoms centred on a self-perpetuating thalamic cell membrane hyperpolarization, similar to the one seen in slow-wave sleep.

Outcome after stereotactic thalamotomy for parkinsonian, essential, and other types of tremor.

A better understanding of the mechanisms underlying movement disorders, coupled with refinements in surgical technique, has led to a resurgence of interest in the surgical treatment of patients with tremor. We retrospectively analyzed the outcomes of 60 patients (62 patient sides) with medically intractable tremor who underwent stereotactic thalamotomy. Of these 60 patients, 42 had Parkinson's disease (of whom 2 patients underwent bilateral surgery for a total of 44 patient sides), 6 had essential tremor, 6 had cerebellar tremor, and 6 had post-traumatic tremor. The patients received follow-up for as long as 13 years (mean, 53.4 mo) after their operations. At the most recent follow-up visit, 86% of the patients with Parkinson's disease, 83% of the patients with essential tremor, 67% of the patients with cerebellar tremor, and 50% of the patients with post-traumatic tremor had cessation of or moderate-to-marked improvement in their contralateral tremor, with a concomitant improvement in function. The mean daily dose of levodopa for those patients preoperatively taking levodopa (n = 35) was reduced by approximately 156 mg at a mean of 53.4 months after thalamotomy. Immediate postoperative complications were common, occurring in 58% of patients. The most common complications were contralateral weakness (34%), dysarthria (29%), and confusion (23%). These complications generally resolved rapidly during the postoperative period.

Outcome after Stereotactic Thalamotomy for Parkinsonian, Essential, and Other Types of Tremor

Outcome after Stereotactic Thalamotomy for Parkinsonian, Essential, and Other Types of Tremor

Outcome after Stereotactic Thalamotomy for Dystonia and Hemiballismus

The outcome after single or staged stereotactic thalamotomies in 17 patients with dystonia and 2 patients with hemiballismus is reviewed. All patients were severely disabled by their movement disorders despite optimal pharmacological therapies. Eight of the patients with dystonia (47%) showed moderate improvement immediately after the procedures. Six of these eight patients maintained their improvement, and two other patients with dystonia improved significantly, during the follow-up period (mean, 37.6 mo). The long-term outcome was better in patients with secondary dystonia (50% moderately or markedly improved at a mean of 41.0 mo) than in patients with primary dystonia (43% moderately or markedly improved at a mean of 32.9 mo). Excellent control was achieved in both of the patients who underwent thalamotomies for hemiballismus.

Outcome after Stereotactic Thalamotomy for Dystonia and Hemiballismus

Outcome after Stereotactic Thalamotomy for Dystonia and Hemiballismus

Technique of stereotactic medial thalamotomy with the Leksell Gamma Knife for treatment of chronic pain.

Nineteen patients underwent a total of 24 medial thalamic lesions made with the Leksell Gamma Knife for the treatment of chronic intractable pain after extensive prior medical and surgical intervention had failed to provide pain relief. The lesion locations were based on prior experience with open radiofrequency medial thalamotomies for the treatment of pain and were directed at the intralaminar, mediodorsal, centromedian, and parafascicular nuclei. All lesions were made with the 4 mm collimator helmet at radiosurgical doses from 140-180 Gray. Follow-up MRI scans indicated anatomically distinct lesions which developed 3-6 weeks after the procedure and were fully formed by 8-12 weeks. The lesion volumes averaged 300-400 mm3 for a single isocentre, 600-900 mm3 for two isocentres, and 900-1100 mm3 for three isocentres. One patient developed a lesion 5500 mm3 in volume after a two isocentre lesion at 160 Gray. Of 15 patients who have been followed for more than 3 months (average follow-up 12 months) four patients (27%) are virtually pain free and functioning normally, whereas five other patients (33%) achieved greater than 50% pain relief. Thus 9/15 patients (60%) have had worthwhile benefit from medial thalamotomy with the Gamma Knife. Medial thalamotomy with the Gamma Knife produces thalamic lesions which are reliable in size, shape and location with a low complication rate and offers a minimally invasive, cost effective treatment for certain selected patients with chronic intractable pain.

Combined stereotactic thalamotomy and posteroventral pallidotomy for Parkinson's disease

Stereotactic thalamotomy has traditionally provided good relief of tremor for patients with intractable tremor-dominant Parkinson's disease. However, bradykinesia, dyskinesia, and rigidity are often less reliably treated with this technique. Although posteroventral pallidotomy (PVP) can alleviate dyskinesias, appendicular bradykinesia, and rigidity, tremor may not be completely ameliorated. We have combined Vim/VOp junction thalamotomy and PVP in 29 patients with severe tremor, rigidity, and bradykinesia. Patients underwent unilateral Vim thalamotomy followed at the same sitting by PVP. The distinct physiological consequences of each procedure were documented by intraoperative electromyography (EMG) and video recording, revealing the effects on both tremor and agonist/antagonist co-contraction. Lack of reciprocal inhibition of antagonistic muscle groups often remained following thalamotomy but was eliminated by subsequent PVP. The complementary therapeutic effects of PVP and Vim thalamotomy may be due to the interruption of different neuronal circuits by the two procedures. The effect of Vim thalamotomy has been attributed to the interruption of the rubrothalamocortical loop. PVP interrupts the outflow of the globus pallidus interna (GPi), which may cause disinhibition of locomotor centers in the mesencephalon and spinal cord. There is no direct interruption of the rubrothalamocortical loop by PVP, explaining why this procedure sometimes exacerbates tremor in certain patients. The combination of the two procedures appears to provide excellent relief of the majority of symptoms in patients suffering from tremor-dominant Parkinson's disease.

Combined stereotactic thalamotomy and posteroventral pallidotomy for Parkinson's disease

Stereotactic thalamotomy has traditionally provided good relief of tremor for patients with intractable tremor-dominant Parkinson's disease. However, bradykinesia, dyskinesia, and rigidity are often less reliably treated with this technique. Although posteroventral pallidotomy (PVP) can alleviate dyskinesias, appendicular bradykinesia, and rigidity, tremor may not be completely ameliorated. We have combined Vim/VOp junction thalamotomy and PVP in 29 patients with severe tremor, rigidity, and bradykinesia. Patients underwent unilateral Vim thalamotomy followed at the same sitting by PVP. The distinct physiological consequences of each procedure were documented by intraoperative electromyography (EMG) and video recording, revealing the effects on both tremor and agonist/antagonist co-contraction. Lack of reciprocal inhibition of antagonistic muscle groups often remained following thalamotomy but was eliminated by subsequent PVP. The complementary therapeutic effects of PVP and Vim thalamotomy may be due to the interruption of different neuronal circuits by the two procedures. The effect of Vim thalamotomy has been attributed to the interruption of the rubrothalamocortical loop. PVP interrupts the outflow of the globus pallidus interna (GPi), which may cause disinhibition of locomotor centers in the mesencephalon and spinal cord. There is no direct interruption of the rubrothalamocortical loop by PVP, explaining why this procedure sometimes exacerbates tremor in certain patients. The combination of the two procedures appears to provide excellent relief of the majority of symptoms in patients suffering from tremor-dominant Parkinson's disease. J Image Guid Surg 1:133–140 (1995). © 1996 Wiley-Liss, Inc.

Thalamotomy for Movement Disorders

VL thalamotomy is an excellent choice for the control of tremor in patients with a wide variety of disorders. Parkinson's disease and essential tremor are the best indications, but other disorders also respond. Improvement of bradykinesia and rigidity in Parkinson's disease is achievable but is not as dramatic as hyperkinetic symptoms. Morbidity from thalamotomy is most common with bilateral lesions, and innovative therapies such as thalamic stimulation may have a role when a second contralateral procedure is needed. Thalamotomy is an effective procedure that has probably been underused over the past two decades. With renewed interest in stereotactic neurosurgery, improved imaging, and well-established target localization techniques, the procedure is effective with a high degree of safety. The growing enthusiasm for brain grafting has also stimulated interest in the surgical treatment of movement disorders, and clearly this technique will evolve and progress as well. In the author's opinion, the results of ablative surgery still far exceed those of tissue implantation. For a select group of indications, thalamotomy should be considered in the forefront of options for patients with movement disorders.

Combined Stereotactic Thalamotomy and Posteroventral Pallidotomy for Parkinson's Disease

Combined Stereotactic Thalamotomy and Posteroventral Pallidotomy for Parkinson's Disease

Stereotactic γ-Thalamotomy with a Computerized Brain Atlas

Radiosurgical stereotactic thalamotomy was performed in a patient with parkinsonian tremor with a computerized stereotactic brain atlas, which was transformed to fit the patient's thin-sliced magnetic resonance image to select an optimal target in the nucleus ventralis intermedius of the thalamus. The patient's tremor and rigidity disappeared and have not appeared again for more than 1 year since the eighth postoperative month. A method for converting the presurgically planned stereotactic coordinates in the atlas coordinate system to the coordinates in the frame coordinate system is described.

The combined method of transplantation of foetal substantia nigra and stereotactic thalamotomy for Parkinson's disease.

Five cases with late Parkinson's disease improved following treatment with a combination of foetal substantia nigra grafts and stereotactic thalamotomy. The average Webster's score decreased from 21 to 11 points. This modified method is simple, safe and effective.

Neurotransplantation in Parkinson's Disease: From Open Microsurgery to Bilateral Stereotactic Approach: First Clinical Trial Using Microelectrode Recording Technique

This paper summarizes the results of three controlled clinical trials related to the transplantation of embryonic ventral mesencephalic tissue into the striatum of 46 idiopathic parkinsonian patients exhibiting motor complications on standard levodopa therapy. From January 1988 to April 1990, 30 subjects with fluctuating Parkinson's disease received fetal dopaminergic tissue implants by the open microsurgical technique. In March 1992 the stereotactic approach was adopted for successive fetal mesencephalic cell suspension transplants (7 unilateral and 9 bilateral) into the caudate and putamen of parkinsonian patients with levodopa-induced complex fluctuations and dyskinesias. The neurological assessment performed 12 months before and 3-18 months after transplantation demonstrated a reduction of both the daily time spent in the 'off' condition and the number of daily 'off' periods, and a significant improvement of the motor scale. The stereotactic selective thalamotomy with microelectrode recording was introduced in January 1993, in order to provide a further potential treatment strategy; i.e., the combination of the two surgical trends in Parkinson's disease, the restorative neurotransplantation technique, and the selective lesional approach. In addition to that, microelectrode recording is also used for implantation site selection and functional characterization.