Magnitude of microelectrode refinement in pallidotomy and thalamotomy.

The relative accuracy of starting point algorithms in microelectrode-guided stereotactic pallidotomy and thalamotomy was evaluated using postoperative magnetic resonance imaging (MRI) data. Multiplanar reformations were performed to align postoperative MRI in anterior-posterior, dorsal-ventral and mediolateral planes. Three-dimensional distance and direction from the pallidal and thalamic stereotactic starting points to the respective radiofrequency lesions were measured. Similar magnitude of microelectrode refinement in pallidotomy and thalamotomy suggested similar accuracy of algorithms used to set the stereotactic starting point. Fewer microelectrode-recording tracts were required to identify optimal lesioning sites in thalamotomy compared to pallidotomy. Lesions were consistently localized anterior and superior to the starting point and a refined starting point algorithm may reduce the number of microelectrode recording tracts.

Pallidotomy microelectrode targeting: neurophysiology-based target refinement.

OBJECTIVE: Microelectrode recording can refine targeting for stereotactic radiofrequency lesioning of the globus pallidus to treat Parkinson's disease. Multiple intraoperative microelectrode recording/stimulating tracks are searched and assessed for neuronal activity, presence of tremor cells, visual responses, and responses to kinesthetic input. These physiological data are then correlated with atlas-based anatomic data to approximate electrode location. On the basis of these physiological properties, one or more tracks are selected for lesioning. This study analyzes the track physiological factors that seem most significant in determining the microelectrode recording track(s) that will be chosen for pallidal lesioning. METHODS: Thirty-six patients with Parkinson's disease underwent microelectrode-guided pallidotomy. Between one and five microelectrode recording tracks were made per patient. Usually, one (n = 23) or two (n = 12) of these tracks were lesioned. Electrode positions in the x (mediolateral) and y (anteroposterior) axes were recorded and related to track neurophysiological findings and final lesion location. The stereotactic location and sequence of microelectrode tracks were recorded and plotted to illustrate individual search patterns. These patterns were then compared with those noted in other patients. Neurophysiological data obtained from recording tracks were analyzed. A retrospective analysis of track electrophysiology was performed to determine the track characteristics that seemed most important in the surgeon's choice of the track to lesion. Track physiological properties included general cell spike amplitude, tremor synchronous neuronal firing, kinesthetically responsive neuronal firing, and optic track responses (either phosphenes reported by the patient during track microstimulation or neuronal firing in response to light stimulus into the patient's eyes). Orthogonally corrected postoperative magnetic resonance images were used to confirm the anatomic lesion locations. RESULTS: In patients who had a single mapped track lesioned, specific track electrophysiological characteristics identified the track that would be lesioned most of the time (20 of 24 patients). Tracks that exhibited a combination of tremor synchronous firing, joint kinesthesia, and visual responsivity were lesioned 17 (85%) of 20 times. Analysis of intraoperative electrode movement in the x and y axes indicated a significant subset of moves but did not result in microelectrode positioning closer to the subsequently lesioned track. Accuracy of initial electrode movement in the x and y axes was most highly correlated with a measure of first-track electrophysiological activity. The number of microelectrode recording tracks did not correlate with clinical outcome. Anatomic analysis, using postoperative magnetic resonance imaging, revealed that all lesions were placed in the globus pallidus. Most patients (35 of 36) improved after surgery. CONCLUSION: The level of electrophysiological activity in the first track was the best predictive factor in determining whether the next microelectrode move would be closer to the ultimately lesioned track. The analysis of electrode track location and neurophysiological properties yields useful information regarding the effectiveness of microelectrode searching in the x and y axes. Within an institution, the application of this modeling method may increase the efficiency of the microelectrode refinement process.

Coil occlusion of the parent artery for treatment of symptomatic peripheral intracranial aneurysms.

BACKGROUND AND PURPOSE: Peripheral intracranial aneurysms can be difficult to treat with traditional surgical or embolization techniques that spare the parent vessel. We report the results of our use of coil occlusion of the parent vessel for the treatment of nine peripheral intracranial aneurysms. METHODS: During approximately a 4-year period, nine patients (six men and three women, 27 to 68 years old; average age, 42 years) presented to our institution with peripheral intracranial aneurysms. The aneurysms were located on branches of the right posterior inferior cerebellar artery (n = 2), the right superior cerebellar artery (n = 1), the right anterior inferior cerebellar artery (n = 1), the right posterior cerebral artery (n = 3), the left middle cerebral artery (n = 1), and the left anterior cerebral artery (n = 1). Parent vessel occlusion was performed using microcoils after test injection with amobarbital (Amytal) in eight of the nine cases (one patient was comatose and could not be tested before occlusion). RESULTS: Angiography immediately after the procedure showed aneurysmal occlusion in every patient. Follow-up arteriography, performed in six patients 2 to 12 months after treatment, documented continued aneurysmal occlusion in every case. Three patients exhibited mild, nondisabling neurologic deficits after coil placement; the rest had no new deficits, although one patient was severely disabled from the initial hemorrhage and one patient died of an unrelated cause. CONCLUSION: Our results lend support to the use of parent vessel occlusion for peripheral aneurysms that are difficult to treat surgically or that are not amenable to intra-aneurysmal coil placement.

Intracranial internal carotid artery angioplasty: technique with clinical and radiographic results and follow-up.

OBJECTIVE: Our objective is to describe the use of percutaneous transluminal angioplasty in eight patients with symptomatic high-grade atherosclerotic intracranial internal carotid artery stenoses. We describe our technique for performing the procedure and clinical and radiographic follow-up for an average of 53 months to determine the long-term results. CONCLUSION: Percutaneous transluminal angioplasty was shown to be an efficacious treatment for symptomatic intracranial internal carotid artery atherosclerotic disease in our group of patients.

Pallidotomy lesion locations: significance of microelectrode refinement.

OBJECTIVE: To determine whether stereotactic pallidotomy requires refinement using microelectrode recording to ensure proper lesion placement. METHODS: The experiment approach was based on retrospective comparisons of microelectrode-refined radiofrequency lesion locations with hypothetical unrefined lesion positions. Actual and hypothetical pallidotomy lesions were classified based on their lesion center (thermocoagulative zone) locations and their total lesion areas (surrounding edematous zone) relative to the pallidal target. Assessments were made using postoperative T2-weighted magnetic resonance axial images, which showed both the lesion and globus pallidus (GP). The magnitude of microelectrode refinement from an initial preoperative starting point determined by computed tomography was calculated using stereotactic coordinates and included corrections for the lesioning tract trajectory angle. RESULTS: In all 25 patients, the center of the actual pallidotomy lesion was within the GP. Without microelectrode refinement, 13 of 25 hypothetical lesion positions would have been localized such that the lesion center would not have remained in the GP. In eight cases, microelectrode refinement resulted in no significant change in lesion location, but in one case, microelectrode refinement resulted in lesion center placement away from the GP. CONCLUSION: Kinesthetically driven microelectrode refinement in pallidotomy lesioning seems to be required to ensure proper lesion location within the GP.

Comparative magnetic resonance image-based evaluation of thalamotomy and pallidotomy lesion volumes.

Acute thalamotomy and pallidotomy lesion volumes based on magnetic resonance (MR) images were measured in 22 patients (11 thalamotomy and 11 pallidotomy patients). Thalamotomy inner lesion volumes (0.06 +/- 0.04 ml; thermocoagulative zone) were smaller than pallidotomy inner lesion volumes (0.14 +/- 0.08 ml) as determined using T(1)-weighted 3D-MPRAGE (1.5-mm slice spacing). Similar results were found using T(1)-weighted (6-mm slice spacing) image sets (0.09 +/- 0.05 ml, thalamotomy; 0.13 +/- 0.05 ml, pallidotomy). No differences were found when comparing thalamic or pallidal inner lesion volumes when the comparison was based on T(2) weighted images. Thalamotomy total lesion volumes (thermocoagulative and surrounding edematous zones) were less than pallidotomy total lesion volumes independent of the MR protocol. The difference in thalamotomy and pallidotomy lesion volumes is most likely based on the distance between each discrete lesion placed along the lesioning tracts. In 7 of 11 thalamotomies, this distance was 1 mm with the remaining having 2 mm between each discrete lesion. All pallidotomy discrete lesions were 2 mm apart. More overlap between discrete lesioning sites for thalamotomies is likely to produce reduced lesion volumes.

Analysis of pallidotomy lesion positions using three-dimensional reconstruction of pallidal lesions, the basal ganglia, and the optic tract.

OBJECTIVE: To assess the position of radiofrequency pallidotomy lesions placed using microelectrode stimulation and cellular recordings in relation to a stereotactically defined starting point. Radiofrequency lesion locations were also evaluated in relation to the putamen, posterior limb of the internal capsule, and optic tract. METHODS: Magnetic resonance images obtained from 23 patients with Parkinson's disease who underwent pallidotomy at the University of Kansas Medical Center were analyzed. Using computerized techniques, lesion positions in relation to the midcommissural point and a hypothetical starting point were determined. Data segmentation and three-dimensional reconstruction of pallidal lesions, the internal capsule, and the optic tract allowed assessment of lesion position in relation to internal anatomy. Clinical outcome of pallidotomy was assessed using both the Unified Parkinson's Disease Rating Scale and the Dementia Rating Scale. RESULTS: Pallidal lesions were usually placed anterior and dorsal to the stereotactically defined starting point. The position of pallidal lesions in the men were observed, in four trials, to be significantly more dorsal than the lesions in the women. The outer zone of the lesion was usually adjacent to the internal capsule and the putamen and relatively close to the optic tract. The inner zone of the lesion was usually several millimeters removed from anatomic boundaries of the putamen, internal capsule, and optic tract. Patients achieved favorable outcomes, with reduced dyskinesias and "off" time and improvement of their Parkinsonian symptoms, as evidenced by clinical assessment, the Unified Parkinson's Disease Rating Scale, and the Dementia Rating Scale. CONCLUSION: Microelectrode stimulation and cellular recordings usually led to a final pallidotomy lesion position that deviated from the stereotactically defined starting point. The pallidotomy lesions in the men were observed to be more dorsal than the lesions in the women. Clinical outcomes were not correlated with either lesion location relative to the starting point or distances between the pallidal lesion and the putamen, internal capsule, or optic tract. Kinesthetically responsive cells may be localized generally more anterior and dorsal to the starting point (within the globus pallidus) and may be grouped variably from patient to patient in relation to other basal ganglia structures. Although the primary lesion site is most likely within the sensorimotor region of the globus pallidus internus, the more dorsal locations of responsive cell groups may indicate that some lesion sites may be localized within the globus pallidus externus.

Three-dimensional computerized reconstruction. Illustration of incremental articular cartilage thinning.

RATIONALE AND OBJECTIVES: The authors have addressed the ability of magnetic resonance (MR) imaging to resolve incremental thinning of articular cartilage by assessment of three-dimensional (3-D) and two-dimensional (2-D) representations. METHODS: Using a porcine knee model, sequential cartilage shavings were characterized using a 3-D fat suppressed spoiled gradient-echo (SPGR) MR imaging protocol that provided good contrast between high-signal articular cartilage and lower signal surrounding tissues. Lesion dimensional measurements were made on both MR images and 3-D computerized reconstructions. Volumes of cartilage removed were approximately 0.06 mL. RESULTS: Incremental articular cartilage thinning typically was apparent on 3-D reconstructed images. Three-dimensional articular cartilage reconstructions were effective in depicting location and orientation of shaved cartilage regions. Average percent error associated with length and with measurements based on 2-D MR images was approximately 19% for observer 1 and 33% for observer 2 when compared with direct measurements of the shaved cartilage. Average percent error of thickness measurements based on 2-D MR was approximately 21% for observer 1 and 37% for observer 2. Overall average errors associated with length, width, and thickness measurements were approximately 25%. CONCLUSIONS: Incremental thinning of articular cartilage can be tracked qualitatively and quantitatively using 3-D computerized reconstructions and 2-D MR images. Errors associated with the quantitative measurements can be attributed to limitations of measurement methods and intrinsic limitation of MR resolution.

Magnetic resonance image evaluation of pallidotomy lesions: a volumetric and shape analysis.

Determination of acute pallidotomy-produced lesion volumes, pre- and postpallidotomy globus pallidus (GP) volumes, and assessment of lesion shape using magnetic resonance (MR) imaging-based computerized segmentation (contouring) and three-dimensional rendering was made in 19 patients. Magnetic resonance image slice thickness (1.5 mm or 6 mm) was not found to be a significant factor influencing contour-based pallidotomy lesion volume estimates. Previously reported lesion volumes produced by pallidotomy have often been estimated using the ellipsoid volume formula. Using 1.5-mm-thick MR sections, contour-based pallidotomy-produced lesion volumes were significantly different from those volumes estimated by the ellipsoid formula. Globus pallidus volumes, estimated by contouring T2-weighted MR images, were bilaterally similar (2.4 +/- 0.37 ml [right]; 2.2 +/- 0.45 ml [left]). Postoperative GP volumes were found on the contralateral, unlesioned side to be 2 +/- 0.45 ml and on the lesioned side to be 1.25 +/- 0.45 ml. Using the contralateral, unlesioned side as a reference volume, approximately 39 +/- 14% of the GP was visibly affected on the lesioned side. Seventeen of 18 patients had a favorable outcome with reduced dyskinesias and "off" time with improvement in parkinsonian symptoms. Analysis of computerized three-dimensional rendering of pallidotomy-produced lesions based on MR images showed no relationship between lesioning technique and resulting lesion shape. Important factors in the volumetric analysis of pallidotomy lesions are identified and allow reasonable assessment of the pallidotomy lesion volume and shape and the extent of the affected GP.

Analysis of three-dimensional computerized representations of articular cartilage lesions.

RATIONALE AND OBJECTIVES: The authors assess the accuracy of three-dimensional (3D) computer representations based on magnetic resonance images of articular cartilage lesions, using actual cartilage lesions as reference standards. METHODS: Grade 2 and grade 3 articular lesions were created on articular surfaces of five porcine knee joints. The knees were then imaged using 3D fat-suppressed SPGR acquisition at four different slice thicknesses. Magnetic resonance imaging data sets were transferred to a computer workstation for image processing and 3D reconstruction. Lesion dimensions (length, width, and depth) based on the 3D reconstructed image were compared with the dimensions measured using actual lesions. RESULTS: The average percent error of lesion length, width, and depth based on the 3D images ranged from approximately 8% to 12% when using the thinnest magnetic resonance slice thickness (0.7 mm). CONCLUSIONS: Three-dimensional reconstructed images derived from thin-slice magnetic resonance imaging can provide reasonable representations of true articular cartilage lesion dimensions.

Doppler US of helical flow in the portal vein.

In helical portal venous blood flow, the usual laminar flow in the portal vein is replaced by a spiral. This changes the color Doppler ultrasound (US) appearance to one of alternating or parallel red and blue bands. Duplex US may appear to show hepatopetal, hepatofugal, or simultaneous bidirectional flow depending on placement of the cursor within the helix. Helical portal venous flow is unusual in normal individuals (2.2% of 135 patients). Its presence should prompt further scrutiny for signs of liver disease, particularly portosystemic shunts, as in 20% of 41 patients who subsequently underwent liver transplantation. It is a normal finding immediately after liver transplantation (43% of 35 patients) and transjugular intrahepatic portosystemic shunt (TIPS) creation (28% of 36 patients). In both liver transplant and TIPS recipients, helical flow is usually transient. Its persistence long after transplantation in association with a prolonged increase in portal venous velocity is a useful sign of portal vein stenosis. Helical flow may also occur in cases of neoplastic invasion or displacement of the portal vein.

Synovial cysts of the lumbar spine: diagnosis, surgical management, and pathogenesis. Report of eight cases.

BACKGROUND: Synovial cysts are uncommon extradural degenerative lesions associated with symptoms of lower back pain and radiculopathy. Most of these lesions occur in the lumbar spine at the L4-5 level and to a lesser extent at the L5-S1 and L3-4 levels. METHODS: A retrospective study involving eight patients seen by the neurosurgery service from January 1, 1989, to May 30, 1994, was analyzed. The type, duration, and distribution of symptoms were evaluated, along with the patient's age and sex. All patients had lumbosacral spine x rays and magnetic resonance imaging. Four had a computed tomography-myelogram of the lumbar spine. All patients underwent a laminectomy or hemilaminectomy and cyst excision, and all were followed for a minimum of 1 year. The presence of a synovial cyst was confirmed by histopathology. RESULTS: Of the eight patients, seven had dramatic pain relief with five having complete resolution of pain. The single care of persistent pain was found to be due to scar tissue at the operative site. All five cases of preoperative lower extremity weakness showed complete resolution. Dysesthesia was either unchanged or decreased. CONCLUSIONS: Surgery is a safe, effective treatment for patients with lumbar synovial cysts and is the treatment of choice for these lesions.

Aneurysm of the left middle cerebral artery caused by myxoid degeneration of the vessel wall.

BACKGROUND: Myxoid degeneration of arterial walls may result in dissection and dissecting aneurysms in extracranial and intracranial portions of cerebral arteries. Rarely, saccular aneurysms may also develop on that basis, but thus far these have only been reported in the cervical portions of the carotid arteries. We describe a case of a nondissecting aneurysm of the left middle cerebral artery caused by myxoid degeneration of the media. CASE DESCRIPTION: A 39-year-old man had acute onset of frontal headache and neck stiffness. Computed tomographic scan and lumbar puncture established the presence of subarachnoid hemorrhage. Angiography demonstrated a left middle cerebral artery aneurysm. This was clipped and the wall biopsied. Microscopically the entire thickness of the vascular wall showed marked myxoid alterations. No dissection was present. The patient had an uneventful recovery. CONCLUSIONS: This observation confirms that myxoid degeneration of arterial walls may cause aneurysms with eventual rupture even in the absence of dissection. Rare cases of this type of aneurysm have been reported to occur in the cervical portions of the carotid arteries, but this is the first reported observation of such changes involving an intracerebral artery.

Internal carotid artery sacrifice.

Sacrifice of the ICA can be used to treat a variety of conditions. Whenever possible, temporary occlusion of the carotid artery should be performed before the actual sacrifice to evaluate for tolerance to the occlusion. In many cases, endovascular occlusion of the carotid artery is preferable to surgical occlusion.

Lack of complications in long-term survivors after treatment with Fluosol and oxygen as an adjuvant to radiation therapy for high-grade brain tumors.

PURPOSE: A Phase I/II trial was initiated in 1987 to determine the toxicity/efficacy of the perfluorochemical emulsion Fluosol-DA 20% and 100% oxygen as an adjuvant to conventional radiation therapy for high-grade brain tumors. METHODS AND MATERIALS: Three grade 3 and 15 grade 4 patients received 1 Fluosol administration (8 mL/kg) per week with daily oxygen breathing prior to and during radiation therapy. Megavoltage radiation was delivered to the whole brain at 25 x 1.8 Gy, followed by 10 x 2 Gy to a boost volume, resulting in a total tumor bed dose of 65 Gy in 7 weeks. RESULTS: Of the 18 patients, 10 (nine grade 4, one grade 3) survived more than 1 year postsurgery, six (all grade 4) lived more than 2 years, four of these patients lived more than 3 years, and three patients are alive at times ranging from 250 to 276 weeks. The median survival of the Fluosol group was 75 weeks, not statistically different from 54 weeks for a historical, matched control group. However, a Gehan-Wilcoxon test applied to those patients that survived > 1 year revealed a significant difference (p = 0.0013) in favor of the Fluosol group. Periodic clinical evaluations showed no evidence of any functional or neurological defects that could be attributed to radiation therapy and/or Fluosol. Radiographic studies (computed tomography and magnetic resonance imaging) revealed no structural alterations outside the original tumor volume, and changes within the tumor region were easily assignable to expected effects of tumor, surgery, or radiation alone. CONCLUSION: These results indicate that, although Fluosol/oxygen added to conventional radiation therapy does not enhance survival of patients who succumb to their disease early, it does confer a significant benefit to patients that survive past 1 year. The minimal acute side effects and no long-term deleterious effects suggest that Fluosol/oxygen sensitizes only hypoxic cells, with no effect on well-oxygenated normal tissues within the brain. We have been impressed by the quality of life of the surviving patients following radiation therapy with adjuvant Fluosol+oxygen.

Neurosarcoidosis with unusual MRI findings.

This 53-year-old white male presented with a 4-month-history of weakness and pain. Despite an initial partial response to steroid therapy, his neurologic deterioration progressed culminating in paraparesis, paresthesias, urinary incontinence, altered mentation and a 20 lb weight loss. A gadolinium-enhanced MRI study showed a pattern suggestive of perivascular involvement. A subsequent cerebral biopsy was diagnostic for neurosarcoidosis.

Osteomyelitis of the skull base.

Three cases of osteomyelitis of the skull base with associated problems in diagnosis and therapy are discussed. Patients with atypical skull base osteomyelitis are difficult to diagnose as they have no ear abnormalities, but they often develop multiple cranial nerve deficits mimicking symptoms of a posterior fossa mass. We conclude that computed tomographic scans, magnetic resonance imaging studies, bone scans indium-labeled white blood cell scans, and gallium scans are useful in making the diagnosis. A biopsy of the bony lesion often is needed to identify the causative organism and to rule out a tumor. Intravenously administered antibiotics are the mainstay of therapy and should be continued until 1 week after the gallium scan shows no abnormalities. Follow-up gallium scans then are done at 1 week and 3 months after the cessation of antibiotic therapy to search for a recurrence.

Magnetic resonance image abnormality in migraine with aura.

Cerebral magnetic resonance imaging (MRI) was performed on 18 patients with migraine characterized by aura consisting of both visual symptoms and paresthesias. Fifteen headache-free individuals of the same age range were used as controls. Records were randomized and read in blind fashion by two neuroradiologists. Small subcortical white matter lesions were seen in three migraine cases and two controls. In one migraine case cortical infarctions were seen. In two controls, small areas of increased density similar to those in migraine were seen. No consistent correlation of migraine or its duration with cerebral atrophy was found. It is concluded that identification of both these MRI findings (small subcortical white lesions and cerebral atrophy) as significantly associated with migraine is doubtful.