Scott D. Wait

PROSPECTIVE EVALUATION OF SURGICAL MICROSCOPE–INTEGRATED INTRAOPERATIVE NEAR-INFRARED INDOCYANINE GREEN ANGIOGRAPHY DURING CEREBRAL ARTERIOVENOUS MALFORMATION SURGERY

OBJECTIVEMicroscope-integrated indocyanine green (ICG) fluorescence angiography is a novel technique in vascular neurosurgery with potential utility in treating arteriovenous malformations (AVMs). METHODSWe analyzed the application of intraoperative ICG in 10 consecutive AVM surgeries for which surgical video was available. The ability to distinguish AVM vessels (draining veins, feeding and nidal arteries) from each other and from normal vessel was evaluated, and ICG angiographic findings were correlated with intra- and postoperative findings on digital subtraction angiography (DSA). RESULTSICG angiography was found to be useful by the surgeon in 9 of 10 patients. In 8 patients, it helped to distinguish AVM vessels. In 3 of 4 patients undergoing a postresection injection, it demonstrated that there was no residual arteriovenous shunting. In 1 patient, it helped to identify a small AVM nidus that was otherwise inapparent within a hematoma. Intraoperative DSA showed residual AVM in 2 of 10 patients requiring further resection of AVM not visualized during surgery. CONCLUSIONMicroscope-integrated ICG angiography is a useful tool in AVM surgery. It can be used to distinguish AVM vessels from normal vessels and arteries from veins based on the timing of fluorescence with the dye. Our experience suggests that it is less useful with deep-seated lesions or when AVM vessels are not on the surface. ICG angiography complements rather than replaces DSA.

Hypofractionated CyberKnife radiosurgery for perichiasmatic pituitary adenomas: early results.

OBJECTIVE Radiation therapy is recommended for pituitary tumors that are refractory to surgical and medical therapies. The efficacy of single-fraction radiosurgery is established for these lesions, but lesions within 3 mm of the optic pathway cannot be safely treated with doses higher than 8 to 10 Gy. We hypothesized that the optic nerve will tolerate 5 consecutive daily radiosurgery fractions of 500 cGy with effective tumor control. METHODS We reviewed our first 20 patients with recurrent or residual pituitary adenomas within 3 mm of the optic chiasm treated with the CyberKnife radiosurgery system (Accuray, Inc., Sunnyvale, CA). Tumors were treated with a mean coverage of 97 +/- 2.2% (range, 89.8-99.7%), a mean conformity index of 1.3 +/- 0.2 (range, 1.1-1.6), and a mean treatment isodose line of 74.5 +/- 6.6% (range, 60-86%). The primary end point was an interim analysis of visual preservation, and secondary end points were radiographic and endocrinological tumor control. RESULTS The mean follow-up period for visual field testing was 26.6 +/- 10.5 months (range, 10.6-41 months). The vision of all 14 patients with intact preoperative vision remained intact. Of the 5 patients with impaired vision, 2 remained stable, and 3 improved. No patients vision deteriorated. The mean radiographic follow-up was 29.3 +/- 8.6 months (range, 10.2-40.5 months). On magnetic resonance imaging, 12 tumors were stable, 8 were smaller, and none enlarged. CONCLUSION This preliminary study establishes that the optic nerve and chiasm tolerate CyberKnife hypofractionated radiosurgery of 5 x 500 cGy to perichiasmatic pituitary adenomas. Early data suggest that this dosing paradigm may achieve satisfactory radiographic and endocrinological tumor control for these challenging lesions, but longer follow-up is necessary to confirm these results.OBJECTIVERadiation therapy is recommended for pituitary tumors that are refractory to surgical and medical therapies. The efficacy of single-fraction radiosurgery is established for these lesions, but lesions within 3 mm of the optic pathway cannot be safely treated with doses higher than 8 to 10 Gy. We hypothesized that the optic nerve will tolerate 5 consecutive daily radiosurgery fractions of 500 cGy with effective tumor control. METHODSWe reviewed our first 20 patients with recurrent or residual pituitary adenomas within 3 mm of the optic chiasm treated with the CyberKnife radiosurgery system (Accuray, Inc., Sunnyvale, CA). Tumors were treated with a mean coverage of 97 ± 2.2% (range, 89.8–99.7%), a mean conformity index of 1.3 ± 0.2 (range, 1.1–1.6), and a mean treatment isodose line of 74.5 ± 6.6% (range, 60–86%). The primary end point was an interim analysis of visual preservation, and secondary end points were radiographic and endocrinological tumor control. RESULTSThe mean follow-up period for visual field testing was 26.6 ± 10.5 months (range, 10.6–41 months). The vision of all 14 patients with intact preoperative vision remained intact. Of the 5 patients with impaired vision, 2 remained stable, and 3 improved. No patients vision deteriorated. The mean radiographic follow-up was 29.3 ± 8.6 months (range, 10.2–40.5 months). On magnetic resonance imaging, 12 tumors were stable, 8 were smaller, and none enlarged. CONCLUSIONThis preliminary study establishes that the optic nerve and chiasm tolerate CyberKnife hypofractionated radiosurgery of 5 × 500 cGy to perichiasmatic pituitary adenomas. Early data suggest that this dosing paradigm may achieve satisfactory radiographic and endocrinological tumor control for these challenging lesions, but longer follow-up is necessary to confirm these results.

Developmental venous anomaly, cavernous malformation, and capillary telangiectasia: spectrum of a single disease.

SummaryDevelopmental venous anomalies (DVAs), cavernous malformations, and capillary telangiectasias are related vascular malformations of the central nervous system. Mixed lesions of the central nervous system vasculature have been reported in a host of combinations, including many possible concomitant combinations of cavernous malformations, venous anomalies, capillary telangiectasias, and arteriovenous malformations (AVMs).We describe the natural history of disease in a female with developmental venous anomaly, cavernous malformation, and capillary telangiectasias appearing in sequence.

Evaluation of Angiographically Occult Spinal Dural Arteriovenous Fistulae With Surgical Microscope-Integrated Intraoperative Near-Infrared Indocyanine Green Angiography: Report of 3 Cases

BACKGROUND:Spinal dural arteriovenous fistulae (dAVFs), are lesions involving an aberrant connection between a radicular feeding artery and the venous system of the spinal cord at the dural sleeve of the nerve root. When rare dAVFs are occult on digitally subtracted catheter-based angiography, they present a diagnostic and therapeutic challenge. OBJECTIVE:We report 3 cases of angiographically occult spinal dAVFs that were evaluated during surgery with indocyanine green (ICG) fluorescent microscope-integrated angiography. METHODS:Three patients with clinical and magnetic resonance imaging features suggestive of a spinal dAVF but no abnormality on digital subtraction angiography underwent surgical exploration with the aid of microscope-integrated ICG videoangiography. RESULTS:In all 3 cases, ICG identified the intradural vein draining the fistula, clearly distinguishing it from an artery or uninvolved medullary vein. CONCLUSION:ICG angiography can rapidly identify a draining vein as it enters the spinal canal even in dAVFs not identifiable on catheter-based digital subtraction angiography.

Thoracoscopic resection of symptomatic herniated thoracic discs: clinical results in 121 patients.

Study Design. Retrospective review of a prospectively maintained surgical database. Objective. To report the indications, surgical procedures performed, and outcomes from the largest series of thoracoscopically treated herniated thoracic discs (HTDs). We also compared approach-related complications with an unmatched cohort undergoing thoracotomy for HTD. Summary of Background Data. Symptomatic HTDs are rare, and their surgical management is technically challenging. Methods. A prospectively maintained surgical database of all patients undergoing surgery for symptomatic HTDs by the senior author (blinded for review) was reviewed. As needed, the database was supplemented with hospital and clinic charts and telephone conversations with patients. A triportal method of thoracoscopic discectomy was performed in all cases. Results. Between 1994 and 2008, 121 patients underwent 125 thoracoscopic-assisted operations for 139 HTDs. Their mean age at surgery was 46.6 years. Indications for thoracoscopic resection currently include small symptomatic disc, anterior location, nonmorbidly obese patient, favorable chest anatomy, and T4–T11 location. Symptom duration averaged 32 months. Radiculopathy was the most common presentation, followed by myelopathy and pain (radiculopathic or back). The mean hospital stay was 4.8 days. Chest tubes remained in place for a mean of 3.2 days. At a mean follow-up of 2.4 years, myelopathy, radiculopathy, and back pain had resolved or improved at a rate of 91.1%, 97.6%, and 86.5%, respectively. Patients reported worsening in 0%, 1.2%, and 0% of cases, respectively. Most patients (97.4%) would be willing to undergo the operation again. The complication rate was acceptable. Patients undergoing thoracoscopic excision had less approach-related morbidity than an unmatched cohort undergoing excision using thoracotomy. Conclusion. Thoracoscopic-assisted microsurgical resection is a safe, effective, and minimally invasive method of treating symptomatic HTDs in appropriately selected patients. The symptoms of most patients improve or resolve with minimal morbidity.

Endoscopic Resection of Colloid Cysts: Use of a Dual-Instrument Technique and an Anterolateral Approach

OBJECTIVE Endoscopic approaches are increasingly utilized to treat third ventricular colloid cysts but have been associated with lower rates of complete cyst wall resection. Our objective was to assess the results of colloid cyst resection via an anterolateral endoscopic approach with a dual-instrument technique, with an emphasis on completeness of cyst wall resection. METHODS A retrospective review of the senior authors experience with 22 colloid cysts treated with endoscopic resection since 2004 was performed. Initial cyst size, completeness of resection, postoperative radiographic residual, recurrence at follow-up, need for reoperation, and neurologic morbidity were assessed. All cysts were approached from an anterolateral trajectory with two instruments working in concert through a single endoscope. RESULTS Of 22 patients, near-total resection was obtained in 95%. In 3 cases, a very small, radiographically occult residual was left. Complete cyst wall resection was therefore obtained in 18 (82%). There were no cases of recurrence at follow-up in any patient. No patients required craniotomy or underwent re-resection. Fifteen of 16 (94%) patients with long-term clinical follow-up remained stable or improved. CONCLUSION High rates of complete colloid cyst resection, with low morbidity, are possible with an anterolateral endoscopic approach with dual-instrument technique. These results support the findings of other endoscopists that show how technical modifications to traditional endoscopic approaches can produce favorable results.

Thoracoscopic sympathectomy for hyperhidrosis: analysis of 642 procedures with special attention to Horner's syndrome and compensatory hyperhidrosis.

BACKGROUNDHyperhidrosis (HH) profoundly affects a patients well-being. OBJECTIVEWe report indications and outcomes of 322 patients treated for HH via thoracoscopic sympathectomy or sympathotomy at the Barrow Neurological Institute. METHODSA prospectively maintained database of all patients who underwent sympathectomy or sympathotomy between 1996 and 2008 was examined. Additional follow-up was obtained in clinic, by phone, or by written questionnaire. RESULTSA total of 322 patients (218 female patients) had thoracoscopic treatment (mean age 27.6 years; range, 10–60 years). Mean follow-up was 8 months. Presentations included HH of the palms (43 patients, 13.4%), axillae (13 patients, 4.0%), craniofacial region (4 patients, 1.2%), or some combination (262 patients, 81.4%). Sympathectomy and sympathotomy were equally effective in relieving HH. Palmar HH resolved in 99.7% of patients. Axillary or craniofacial HH resolved or improved in 89.1% and 100% of cases, respectively. Hospital stay averaged 0.5 days. Ablating the sympathetic chain at T5 increased the incidence of severe compensatory sweating (P = .0078). Sympathectomy was associated with a significantly higher incidence of Horners syndrome compared with sympathotomy (5% vs 0.9%, P = .0319). Patients reported satisfaction and willingness to undergo the procedure again in 98.1% of cases. CONCLUSIONThoracoscopic sympathectomy is effective and safe treatment for severe palmar, axillary, and craniofacial HH. Ablating the T5 ganglion tends to increase the severity of compensatory sweating. Sympathectomy led to a higher incidence of ipsilateral Horners syndrome compared with sympathotomy.

Use of flexible hollow-core CO2 laser in microsurgical resection of CNS lesions: early surgical experience.

INTRODUCTIONThe CO2 laser has a long history in both experimental and clinical neurosurgery. However, its use over the past decade has been limited by its cumbersome design and bulky set-up of the micromanipulator. These limitations are amplified when it is used with the operating microscope. These restrictions are addressed by the Omniguide fiber, which delivers the beam through flexible hollow-core photonic bandgap mirror fibers and allows the laser to be wielded like any other surgical instrument. METHODSThe attending neurosurgeon prospectively assessed the usefulness of the laser in its first 45 consecutive uses at our institution based on a scale of 1 to 5. RESULTSThe series included 11 cavernous malformations, 14 meningiomas, 7 ependymomas, 3 metastases, 3 astrocytomas, and 7 miscellaneous lesions. The laser was set up 91 times and used in 45 cases. The Omniguide fiber failed 5 times. No adverse events involving patients or staff were associated with laser use. The mean utility score was 3.7 ± 0.8 (range, 2–5). The laser was most helpful in debulking fibrous lesions too tough for ultrasonic aspiration and lesions adherent to delicate neurovascular structures. The laser was not helpful with highly vascular tumors. CONCLUSIONIn our early experience, the Omniguide laser was very helpful in selected cases in resecting specific types of lesions without complications; we have added the device to our neurosurgical armamentarium.

Endoscopic resection of intrathoracic tumors: experience with and long-term results for 26 patients

OBJECT Thoracoscopy may be used in place of thoracotomy to resect intrathoracic neoplasms such as paraspinal neurogenic tumors. Although these tumors are rare, they account for the majority of tumors arising in the posterior mediastinum. METHODS A database was maintained of all patients undergoing thoracoscopic surgery for tumors. The authors analyzed the presenting symptoms, pathological diagnoses, and outcomes of 26 patients (7 males and 19 females, mean age 37.2 years) who were treated for intrathoracic tumors via thoracoscopy between January 1995 and May 2009. Fourteen patients were diagnosed incidentally (54%). Five patients (19%) presented with dyspnea or shortness of breath, 4 (15%) with pain, 1 (4%) with pneumonia, 1 (4%) with hoarseness, and 1 (4%) with Horner syndrome. RESULTS Pathology demonstrated schwannomas in 20 patients (77%). Other diagnoses included ganglioneurofibroma, paraganglioma, epithelioid angiosarcoma, benign hemangioma, benign granular cell tumor, and infectious granuloma. One patient required conversion to open thoracotomy due to pleural scarring to the tumor. One underwent initial laminectomy due to intraspinal extension of the tumor. Gross-total resection was obtained in 25 cases (96%). The remaining patient underwent biopsy followed by radiation therapy. The mean surgical time was 2.5 hours, and the mean blood loss was 243 ml. The mean duration of chest tube insertion was 1.3 days, and the mean length of hospital stay was 3.0 days. Cases that were treated in the second half of the cohort were more often diagnosed incidentally, performed in less time, and had less blood loss than those in the first half of the cohort. There was 1 case of permanent treatment-related morbidity (mild Horner syndrome). All previously employed patients were able to return to work (mean clinical follow-up 43 months). There were no recurrences (mean imaging follow-up 54 months). CONCLUSIONS Endoscopic transthoracic approaches can reduce approach-related soft-tissue morbidity and facilitate recovery by preserving the normal tissues of the chest wall, by avoiding rib retraction and muscle transection, and by reducing postoperative pain. This less invasive approach thus shortens hospital stay and recovery time.

Firing behavior and network activity of single neurons in human epileptic hypothalamic hamartoma

Objective: Human hypothalamic hamartomas (HH) are intrinsically epileptogenic and are associated with treatment-resistant gelastic seizures. The basic cellular mechanisms responsible for seizure onset within HH are unknown. We used intra-operative microwire recordings of single neuron activity to measure the spontaneous firing rate of neurons and the degree of functional connection between neurons within the tumor. Technique: Fourteen patients underwent transventricular endoscopic resection of HH for treatment-resistant epilepsy. Prior to surgical resection, single neuron recordings from bundled microwires (total of nine contacts) were obtained from HH tissue. Spontaneous activity was recorded for two or three 5-min epochs under steady-state general anesthesia. Off-line analysis included cluster analysis of single unit activity and probability analysis of firing relationships between pairs of neurons. Results: Altogether, 222 neurons were identified (mean 6 neurons per recording epoch). Cluster analysis of single neuron firing utilizing a mixture of Gaussians model identified two distinct populations on the basis of firing rate (median firing frequency 0.6 versus 15.0 spikes per second; p < 10−5). Cluster analysis identified three populations determined by levels of burst firing (median burst indices of 0.015, 0.18, and 0.39; p < 10−15). Unbiased analysis of spontaneous single unit behavior showed that 51% of all possible neuron pairs within each recording epoch had a significant level of firing synchrony (p < 10−15). The subgroup of neurons with higher median firing frequencies was more likely to demonstrate synchronous firing (p < 10−7). Conclusion: Hypothalamic hamartoma tissue in vivo contains neurons which fire spontaneously. The activity of single neurons is diverse but distributes into at least two electrophysiological phenoytpes. Functional linkage between single neurons suggests that HH neurons exist within local networks that may contribute to ictogenesis.