✓ The authors report a new technique to anchor deep brain stimulation electrodes using a titanium microplate. This technique has been safely used to secure 20 quadripolar deep brain stimulation electrodes implanted for movement disorders (18 electrodes) and pain (two electrodes). Twelve electrodes were implanted in the thalamus, four in the subthalamic nucleus, and four in the pallidum. No electrode migration or rupture occurred, and all electrodes have been shown to work properly after internalization of the system.
Jacques Favre, Jamal M. Taha, Timothy Steel and Kim J. Burchiel
Case report and review of the literature
Konstantin V. Slavin, Thomas K. Baumann and Kim J. Burchiel
Hemiballismus is a relatively rare movement disorder that is characterized by uncontrolled, random, large-amplitude movements of the limbs. It is usually caused by a vascular lesion that involves the contralateral subthalamic nucleus (STN) (also known as the nucleus hypothalamicus or corpus luysi) and its afferent and efferent pathways.
The authors present a case of medically intractable hemiballismus in a 70-year-old woman who was successfully treated with stereotactic posteroventral pallidotomy. In agreement with the data reported earlier by other groups, the microrecording performed during the pallidotomy showed a decreased rate of firing of the pallidal neurons, supporting the theory of impaired excitatory input from the STN to the internal part of the globus pallidus.
Stereotactic pallidotomy may be the procedure of choice in the treatment of medically intractable hemiballismus. Intraoperative microrecording significantly improves the precision of the stereotactic targeting and should be considered a standard part of the pallidotomy protocol.
Daniel C. Rohrer, Kim J. Burchiel and David P. Gruber
✓ A diverse collection of unverified theories as to the etiology of extradural meningeal cysts have been previously proposed. One case of intraspinal extradural meningeal cyst of the thoracolumbar region is presented in which a ball-valve mechanism involving an idiopathic dural rent and a herniated segment of an underlying dorsal rootlet was suggested by the operative findings. Closure of the dural rent with marsupialization of the meningeal cyst obliterated this extradural lesion. The ball-valve mechanism of formation and other previously proposed theories are discussed.
Jamal M. Taha, Jacques Favre, Thomas K. Baumann and Kim J. Burchiel
✓ The goals of this study were to analyze the effect of pallidotomy on parkinsonian tremor and to ascertain whether an association exists between microrecording findings and tremor outcome.
Forty-four patients with Parkinson's disease who had drug-induced dyskinesia, bradykinesia, rigidity, and tremor underwent posteroventral pallidotomy. Using a 1-µ-tip tungsten electrode, microrecordings were obtained through one to three tracts, starting 10 mm above the pallidal base. Tremor severity was measured on a patient-rated, 100-mm Visual Analog Scale (VAS), both preoperatively and 3 to 9 months (mean 6 months) postoperatively.
Preoperatively, tremor was rated as 50 mm or greater in 24 patients (55%) and as less than 25 mm in 13 patients (30%). Postoperatively, tremor was rated as 50 mm or greater in five patients (11%) and less than 25 mm in 29 patients (66%). The difference was significant (p = 0.0001). Four patients (9%) had no postoperative tremor. Tremor improved by at least 50% in eight (80%) of 10 patients in whom tremor-synchronous cells were recorded (Group A) and in 12 (35%) of 34 patients in whom tremor-synchronous cells were not recorded (Group B). This difference was significant (p = 0.03). Tremor improved by at least 50 mm in all (100%) of the seven Group A patients with severe (≥ 50 mm) preoperative tremor and in nine (53%) of 17 Group B patients with severe preoperative tremor. This difference was also significant (p = 0.05).
The authors proffer two conclusions: 1) after pallidotomy, tremor improves by at least 50% in two-thirds of patients with Parkinson's disease who have severe (≥ 50 mm on the VAS) preoperative tremor; and 2) better tremor control is obtained when tremor-synchronous cells are included in the lesion.
Andrew C. Zacest, Stephen T. Magill, Valerie C. Anderson and Kim J. Burchiel
Ilioinguinal neuralgia is one cause of chronic groin pain following inguinal hernia repair, and it affects ~ 10% of patients. Selective ilioinguinal neurectomy is one proposed treatment option for carefully selected patients. The goal of this study was to determine the long-term outcome of patients who underwent selective ilioinguinal neurectomy for chronic post-hernia pain.
The authors retrospectively reviewed the clinical assessment, surgical treatment, and long-term outcome in 26 patients with ilioinguinal neuralgia who underwent selective ilioinguinal neurectomy performed by the senior author (K.J.B.) at Oregon Health & Science University between 1998 and 2008. Data were collected from patient charts and a follow-up telephone questionnaire.
Twenty-six patients (14 men and 12 women) had a clinical diagnosis of ilioinguinal neuralgia based on a history of radiating neuropathic groin, medial thigh, and genitalia pain. One patient had bilateral disease (therefore there were 27 surgical cases). A selective nerve block was performed in 21 (81%) of 26 patients and was positive in 20 (77%) of the 26. In all but 2 patients, pain onset followed abdominal surgery (for hernia repair in 18 patients), and was immediate in 16 (67%) of 24 patients. The mean patient age was 48.7 years, and the mean duration of pain prior to neurosurgical consultation was 3.9 years. Surgery was performed after induction of local or general anesthesia in 17 and 10 cases, respectively. The ilioinguinal nerve was identified in 25 cases, and the genitofemoral nerve in 2, either entrapped in mesh, scar, or with obvious neuroma (22 of 27 cases). The identified nerve was doubly ligated, cut, and buried in muscle at its most proximal point. At the 2-week follow-up evaluations, 14 (74%) of 19 patients noted definite pain improvement.
Nineteen (73%) of the 26 patients were contacted by telephone and agreed to participate in completing long-term follow-up questionnaires. The mean follow-up duration was 34.78 months. Return of pain was reported by 13 (68%) of 19 patients. Using a verbal numerical rating scale (0–10), pain was completely relieved in 27.8%, better in 38.9%, no better in 16.7%, and worse in 16.7% of patients.
Ilioinguinal neurectomy is an effective and appropriate treatment for selected patients with iatrogenic ilioinguinal neuralgia following abdominal surgery. Although a high proportion of patients reported some long-term recurrence of pain, complete or partial pain relief was achieved in 66.7% of the patients observed.
Roberto C. Heros
Jonathan P. Miller, Stephen T. Magill, Feridun Acar and Kim J. Burchiel
Microvascular decompression (MVD) is an effective treatment for trigeminal neuralgia (TN). However, many patients do not experience complete pain relief, and relapse can occur even after an initial excellent result. This study was designed to identify characteristics associated with improved long-term outcome after MVD.
One hundred seventy-nine consecutive patients who had undergone MVD for TN at the authors' institution were contacted, and 95 were enrolled in the study. Patients provided information about preoperative pain characteristics including preponderance of shock-like (Type 1 TN) or constant (Type 2 TN) pain, preoperative duration, trigger points, anticonvulsant therapy response, memorable onset, and pain-free intervals. Three groups were defined based on outcome: 1) excellent, pain relief without medication; 2) good, mild or intermittent pain controlled with low-dose medication; and 3) poor, severe persistent pain or need for additional surgical treatment.
Type of TN pain (Type 1 TN vs Type 2 TN) was the only significant predictor of outcome after MVD. Results were excellent, good, and poor for Type 1 TN versus Type 2 TN patients in 60 versus 25%, 24 versus 39%, and 16 versus 36%, respectively. Among patients with each TN type, there was a significant trend toward better outcome with greater proportional contribution of Type 1 TN (lancinating) symptoms (p < 0.05).
Pain relief after MVD is strongly correlated with the lancinating pain component, and therefore type of TN pain is the best predictor of long-term outcome after MVD. Application of this information should be helpful in the selection of TN patients likely to benefit from MVD.
Jonathan P. Miller, Feridun Acar, Bronwyn E. Hamilton and Kim J. Burchiel
Neurovascular compression (NVC) of the trigeminal nerve is associated with trigeminal neuralgia (TN), but also occurs in many patients without facial pain. This study is designed to identify anatomical characteristics of NVC associated with TN.
Thirty patients with Type 1 TN (intermittent shocklike pain) and 15 patients without facial pain underwent imaging for analysis of 30 trigeminal nerves ipsilateral to TN symptoms, 30 contralateral to TN symptoms, and 30 in asymptomatic patients. Patients underwent 3-T MR imaging including balanced fast-field echo and MR angiography. Images were fused and reconstructed into virtual cisternoscopy images that were evaluated to determine the presence and degree of NVC. Reconstructed coronal images were used to measure nerve diameter and crosssectional area.
The incidence of arterial NVC in asymptomatic nerves, nerves contralateral to TN symptoms, and nerves ipsilateral to TN symptoms was 17%, 43%, and 57%, respectively. The difference between symptomatic and asymptomatic nerves was significant regarding the presence of NVC, nerve distortion, and the site of compression (p < 0.001, Fisher exact test). The most significant predictors of TN were compression of the proximal nerve (odds ratio 10.4) and nerve indentation or displacement (odds ratio 4.3). There was a tendency for the development of increasingly severe nerve compression with more advanced patient age across all groups. Decreased nerve size was observed in patients with TN but did not correlate with the presence or extent of NVC.
Trigeminal NVC occurs in asymptomatic patients but is more severe and more proximal in patients with TN. This information may help identify patients who are likely to benefit from microvascular decompression.
Roberto C. Heros
Jamal M. Taha, Jacques Favre, Thomas K. Baumann and Kim J. Burchiel
✓ Information is limited on the characteristics and topographic localization of pallidal kinesthetic cells in patients with Parkinson's disease. The authors analyzed the data from 298 neurons recorded in 38 patients with Parkinson's disease who underwent pallidotomy via microrecording techniques. Sixty-five neurons (22%) responded to passive movement of contralateral limbs. Of 17 kinesthetic cells that were tested in six patients, seven (41%) responded to ipsilateral limb movement as well. Nineteen cells (6%) fired synchronously with tremor. More kinesthetic cells were activated (63%) than inhibited (28%) by movement of single (68%) rather than multiple (32%) joints, and proximal (75%) rather than distal (25%) joints. The lateral globus pallidus externus (GPe) and medial globus pallidus internus (GPi) pallidal segments contained similar proportions of kinesthetic cells, activated or inhibited cells, arm- or leg-activated cells, and cells responding to single or multiple joints. Significantly more kinesthetic cells that responded to distal joints were recorded in GPi compared to GPe segments (p = 0.01). Arm and leg cells had similar characteristics pertaining to activation versus inhibition and responses to single, multiple, proximal, or distal joint movements. Arm and leg cells were somatotopically organized in GPi. Arm cells were clustered at the rostral and caudal segments of GPi and leg cells were clustered centrally. In GPe, leg cells were clustered at the caudal border. No somatotopic organization was identified for activated or inhibited cells; cells that responded to single, multiple, proximal, or distal joints; tremor-synchronous cells; or cells responding to specific joints within somatotopic arm or leg cells. It is concluded that kinesthetic cells provide a roadmap that localizes limb cells during pallidotomy. More studies are needed to identify the clinical significance of the different characteristics of kinesthetic cells.