Zvi Lidar

Linear accelerator radiosurgery for vestibular schwannoma

OBJECT The use of radiosurgery in the treatment of acoustic neuromas has increased substantially during the last decade. Most published experience relates to the use of the gamma knife. In this report, the authors review the methods and results of linear accelerator (LINAC) radiosurgery in 44 patients with acoustic neuromas who were treated between 1993 and 1997. METHODS Computerized tomography scanning was selected as the stereotactic imaging modality for target definition. A single, conformally shaped isocenter was used in the treatment of 40 patients; two or three isocenters were used in four patients who harbored very irregular tumors. The radiation dose directed to the tumor border was the only parameter that changed during the study period: in the first 24 patients who were treated the dose was 15 to 20 Gy, whereas in the last 20 patients the dose was reduced to 11 to 14 Gy. After a mean follow-up period of 32 months (range 12-60 months), 98% of the tumors were controlled. The actuarial hearing preservation rate was 71%. New transient facial neuropathy developed in 24% of the patients and persisted to a mild degree in 8%. Radiation dose correlated significantly with the incidence of cranial neuropathy, particularly in large tumors (> or = 4 cm3). CONCLUSIONS Single-isocenter LINAC radiosurgery proved to be an effective treatment for acoustic neuromas in this series, with results that were comparable with those reported for gamma knife radiosurgery and multiple isocenters.

Minimally invasive transforaminal, thoracic microscopic discectomy: technical report and preliminary results and complications

BACKGROUND CONTEXT Surgical decompression of thoracic disc herniations is technically challenging because retraction of the thecal sac in this area must be avoided. Standard open thoracic discectomy procedures require fairly extensive soft tissue dissection and vertebral resection to provide safe decompression of the spinal cord. PURPOSE To describe our experience using a minimally invasive, transforaminal thoracic discectomy (MITTD) technique for the treatment of thoracic disc herniation. STUDY DESIGN Technical report and preliminary results and complications. METHODS Twelve patients undergoing MITTD were evaluated preoperatively and postoperatively at 1-, 3-, and 6-month intervals with neurologic examination, and were graded using the American Spinal Injury Association (ASIA) impairment scale and a pain visual analog scale (VAS). Thoracic instability and bony fusion were assessed clinically and radiographically with plain radiographs and computed tomography (CT) scans. Surgical time, blood loss, complications, and hospital length of stay were recorded. RESULTS Twelve patients (seven men and five women) underwent MITTD. The median surgical time was 128 (80 to 185) minutes, the median estimated blood loss was 100 (30 to 250) mL, and the median hospital stay was 2 (1 to 4) nights. All discs were successfully removed, and a CT or magnetic resonance imaging confirmed adequate cord decompression in all cases. All patients reported easing of neurologic symptoms and improved walking ability. The median VAS scores improved from 4.5 to 2 for back pain. The ASIA score improved from D to E in the two patients who suffered from motor weakness. Preoperative sensory deficit was reduced in three of the five patients. Patients who suffered from sexual and urinary disturbances did not report improvement. Serious systemic or local complications and neurologic deterioration were not reported. CONCLUSIONS The transforaminal approach enabled sufficient access to the midline of the spinal canal without extensive resection of the facet joint or the adjacent pedicle. Because most of the osseous and ligamentous structures were preserved, additional instrumentation was not required to prevent postoperative instability. Our early results suggested that minimally invasive thoracic discectomy by transforaminal microscopic technique is a valuable choice in the management of thoracic disc herniation.

Minimally invasive posterior cervical discectomy for cervical radiculopathy: technique and clinical results.

Study Design Retrospective analysis of data of all patients treated by minimally invasive posterior discectomy for cervical radiculopathy between January 2004 and February 2008. Objetive To describe our technique and report the outcome of minimally invasive posterior cervical discectomy using the MetRx tubular retractor system and surgical microscope. Summary of Background Data Although several studies have been published on posterior minimally invasive approaches to cervical radiculopathy, most have focused on decompression of the nerve root by laminoforaminotomy only without the removal of the offending disc. Methods The hospital charts, magnetic resonance imaging studies, and follow-up records of all the patients were reviewed. Outcome was assessed by neurological status, visual analog scale (VAS) for neck and arm pain, and by the short form-36 health survey questionnaire. Results Thirty-two patients were included in this study. The follow-up time was 20 to 67 months (mean, 39 mo). Muscle weakness improved in all patients; sensory deficits resolved in 21 patients and improved in 7 patients. Analysis of the mean VAS for radicular pain, VAS for neck pain, and all 8 domains of the short form-36 health survey questionnaire showed significant improvement. Complications included 1 case of incidental dural tear without postoperative cerebrospinal fluid leakage and 1 case of longstanding neck pain. Conclusion Minimally invasive posterior cervical discectomy is safe and effective in the management of lateral cervical disc herniation manifested by radiculopathy. In addition to eliminating some of the disadvantages of open surgical approaches, it may also have swifter symptoms resolution compared with laminoforaminotomy without discectomy.

Delay in diagnosis of primary intradural spinal cord tumors

Background: It has been our impression in recent years that there is a significant delay in diagnosis (DID) of patients in Israel harboring intradural spinal cord tumors (IDSCTs). DID can lead to irreversible deficits and unnecessary suffering. Our goal was to identify the incidence and the specific reasons for DID of IDSCTs in patients operated upon at our institution. Methods: A retrospective record review, with additional telephone survey, of 101 patients operated upon at our institute between the years 1996 and 2009 was conducted. The patients who were not diagnosed locally and those who were diagnosed during routine spinal imaging studies as part of their basic disease check-up were excluded. Accordingly, neurofibromatosis and medical tourist patients were excluded. Results: The clinical presentation of IDSCTs in our study was similar to the descriptions given in previous reports. The average age was 41.9 ± 23.3 years. Most tumors were ependymomas, astrocytomas, and schwannomas. The most common symptoms were motor or sensory disturbance, back pain, walking disturbance, and sphincter control deficit. The median time to diagnosis was 12.0 ± 37.0 months (range 3 days to 20 years). We found DID in 82.2% of the cases. 62.4% of the cases were defined as “unreasonable delay.” The most common reasons for DID were “classical symptoms with a wrong diagnosis” and “delayed imaging.” Conclusions: Based on the results of this study, the incidence of unreasonable delays in diagnosis of primary IDSCTs in Israel is very high. In order to shorten the time to diagnosis, primary and secondary care physicians need to increase their awareness of symptoms that may be associated with these lesions. We hereby offer feedback for care providers, relevant to the diagnostic workup of these patients. Such a feedback must be delivered by neurosurgeons to the community they are serving.

Sarcoidosis Presenting as “Corset-like” Myelopathy: A Description of Six Cases and Literature Review

Sarcoidosis of the spinal cord is rare, even more so as the initial presentation of the disease. We describe six cases of spinal cord sarcoidosis and delineate a distinguishing feature which may allow for a timely diagnosis. All patients were admitted with complaints of a “corset-like” pressure in the lower chest and later developed cranial nerve palsies (two patients), parasthesias/paraparesis (two patients), fever of unknown origin (one patient), and bilateral proptosis (one patient). Serological tests, immunological screening, cerebrospinal fluid (CSF) analysis, bacteriological and viral testing were performed in all patients. Spinal and cerebral MRI, high-resolution computed tomography (HRCT) of the chest and gallium scan suggested the diagnosis of neurosarcoidosis of the spine while a biopsy of mediastinal lymph nodes, extra-ocular muscles, or spinal cord confirmed it. CSF showed inflammatory signs in 66% of patients and serum ACE levels were increased in a similar fraction. MRI revealed a gadolinium-enhanced thickening of the cord at the thoracic level in three patients whereas three other patients had normal spinal MRI despite similar symptoms. The presence of mediastinal lymphadenopathy on HRCT of the chest suggested the diagnosis in a third of patients. Patients were treated with steroid, immunosuppressive therapy and/or biologic therapies, with complete resolution in one case, improvement in four, and a somewhat deteriorating course, with development of spinal cord atrophy in the final case. As spinal cord involvement of sarcoidosis is extremely rare, making the diagnosis in the absence of systemic disease is challenging. The cases herein described suggest that sensory disturbance in a “corset-like” distribution may be indicative of neurosarcoidosis, especially when accompanied by extra-axial involvement such as cranial nerve palsies. This should prompt an evaluation for systemic involvement, keeping in mind that serum ACE and chest radiographs may be normal in the presence of primarily CNS-limited disease.

Absorbable anterior cervical plate for corpectomy and fusion in a 2-year-old child with neurofibromatosis

Postlaminectomy cervical kyphosis is one of the most challenging entities in spine surgery. Correction of this deformity usually requires anterior fusion with plating and a strut graft or interbody cage and posterior fusion with screws and rods. The situation is more complicated in the young child because fusion may affect future growth of the cervical spine. There is also a paucity of adequate instrumentation for the small bony structures. Some authors have reported utilization of absorbable cervical plates for fusion in pediatric patients with favorable results. The authors present a modified surgical technique that was used for circumferential fusion in a 2-year-old girl with cervical kyphosis and recurrent neurofibroma. Anterior fusion was performed using an autologous rib graft and an absorbable cervical plate. This was followed by posterior fusion using rib bone and cables. Previous reports on the use of absorbable cervical plates are reviewed and the advantages of the current technique are discussed.

Prevalence and awareness of sacroiliac joint alterations on lumbar spine CT in low back pain patients younger than 40 years.

Background Computed tomography (CT) examinations of the lumbar spine are commonly performed in patients aged ≤40 years due to low back pain (LBP). Purpose To investigate the prevalence and awareness of radiologists for the presence of structural post-inflammatory/other sacroiliac joint (SIJ) alterations on lumbar spine CTs of young patients with LBP. Material and Methods A total of 484 lumbar spine CT examinations (272 men, 212 women; average age, 31 years; age range, 18–40 years) of patients with LBP in which the entire SIJs were visualized were retrospectively reviewed. SIJs were scored (consensus) by two senior radiologists (study reading) for the presence of post-inflammatory structural SIJ findings or other SIJs alterations. The original reports were compared to the study reading. Fifty CT examinations were re-evaluated for reliability assessment (intra-class correlation coefficient [ICC]). Results A total of 150 (31%) abnormal SIJ examinations were registered (ICC: r = 0.7–0.8; P < 0.0001): suspected sacroiliitis = 50 (10.2%); definite sacroiliitis = 16 (3.3%); osteitis-condensans-ilii = 38 (7.8%); diffuse idiopathic skeletal hyperostosis = 24 (5%); degenerative changes = 22 (4.5%); accessory SIJ = 22 (4.5%); and tumor = 1. The SIJs were referenced 39 times (8.0%) in the original readings: pathological findings (n = 15); and normal SIJ (n = 24). Total diagnostic accuracy for these reports only and for the entire readings were 49% and 69%, respectively, and 13% and 1.3%, respectively, for the pathological findings. Conclusion Sacroiliitis and other SIJ alterations are prevalent in young individuals with LBP, albeit, the majority of these alterations are not recognized nor reported by senior radiologists thus may delay efficacious treatment.

Continuous mapping of the corticospinal tracts in intramedullary spinal cord tumor surgery using an electrified ultrasonic aspirator

Intramedullary spinal cord tumors (IMSCTs) represent a rare entity, accounting for 4%-10% of all central nervous system tumors. Microsurgical resection of IMSCTs is currently considered the primary treatment modality. Intraoperative neurophysiological monitoring (IONM) has been shown to aid in maximizing tumor resection and minimizing neurological morbidity, consequently improving patient outcome. The gold standard for IONM to date is multimodality monitoring, consisting of both somatosensory evoked potentials, as well as muscle-based transcranial electric motor evoked potentials (tcMEPs). Monitoring of tcMEPs is optimal when combining transcranial electrically stimulated muscle tcMEPs with D-wave monitoring. Despite continuous monitoring of these modalities, when classic monitoring techniques are used, there can be an inherent delay in time between actual structural or vascular-based injury to the corticospinal tracts (CSTs) and its revelation. Often, tcMEP stimulation is precluded by the surgeons preference that the patient not twitch, especially at the most crucial times during resection. In addition, D-wave monitoring may require a few seconds of averaging until updating, and can be somewhat indiscriminate to laterality. Therefore, a method that will provide immediate information regarding the vulnerability of the CSTs is still needed. The authors performed a retrospective series review of resection of IMSCTs using the tip of an ultrasonic aspirator for continuous proximity mapping of the motor fibers within the spinal cord, along with classic muscle-based tcMEP and D-wave monitoring. The authors present their preliminary experience with 6 patients who underwent resection of an IMSCT using the tip of an ultrasonic aspirator for continuous proximity mapping of the motor fibers within the spinal cord, together with classic muscle-based tcMEP and D-wave monitoring. This fusion of technologies can potentially assist in optimizing resection while preserving neurological function in these challenging surgeries.

A Comparison of Different Minimally Invasive and Open Posterior Spinal Procedures Using Volumetric Measurements of the Surgical Exposures.

Study Design: A Prospective observational study. Summary of the Background Data: Minimally invasive (MI) spine surgery techniques strive to minimize the damage to paraspinal soft tissues. Previous studies used only the length of the surgical incision to quantify the invasiveness of certain MI procedures. However, this method does not take into account the volume of muscle tissue that is dissected and retracted from the spine to achieve sufficient exposure. To date, no simple method has been reported to measure the volume of the surgical exposure and to quantify the degree of surgery invasiveness. Study Objectives: To obtain and compare volumetric measures of various MI and open posterior-approached spinal surgical exposures. Methods: The length, the depth, and the volume of the surgical exposure were obtained from 57 patients who underwent either open or MI posterior lumbar surgery. MI procedures included the following: tubular discectomy, laminotomy, and transforaminal interbody fusion. Open procedures included the following: discectomy, laminectomy, transforaminal interbody fusion, or posterior-lateral instrumented fusion. Four attending spine surgeons at our unit performed the surgeries. To reduce variability, only single-level procedures performed between L4 and S1 vertebrae were used. The volume of exposure was obtained by measuring the amount of saline needed to fill the surgical wound completely once the surgical retractors were deployed and opened. Results: The average volumes in mililiters of exposure for a single-level MI procedure ranged from 9.8±2.8 to 75±11.7 mL and were significantly smaller than the average volumes of exposure for a single level open procedures that ranged from 44± 21 to 277±47.9 P<0.001. The average skin-incision lengths for single-level MI procedures ranged from 1.7±0.2 to 7.7±1.6 cm and were significantly smaller than the average skin-incision lengths for open procedures [5.2±1.4 (Table 3) to 11.3±2 cm, P<0.001]. The measured surgical depths were similar in MI and open groups (P=0.138). MI decompression and posterior fusion procedures yielded 92% and 73% reductions in the volumes of exposure, respectively. However, absolute differences in exposure volumes were larger for fusion (202 mL) compared with decompression alone (110.7 mL). Conclusions: Direct volumetric measurement of the surgical exposure is obtained easily by measuring the amount of saline needed to fill the exposed cavity. Using this method, the needed surgical exposure of different spinal procedures can be quantified and compared. This volumetric measurement combined with the measure of retraction force, the duration of retraction, and the impact on soft tissue vascularity can help build a model that assesses the relative invasiveness of different spinal procedures.

Electrophysiological monitoring during preoperative angiography to guide decisions regarding permanent occlusion of major radicular arteries in patients undergoing total en bloc spondylectomy.

OBJECTIVE Preoperative embolization is performed before spine tumor surgery when significant intraoperative hemorrhage is anticipated. Occlusion of radicular and segmental arteries may result in spinal ischemia. The goal of this study was to check whether neurophysiological monitoring during preoperative angiography in patients scheduled for total en bloc spondylectomy (TES) of spine tumors improves the safety of vessel occlusion. METHODS This was a case series study of patients who underwent tumor embolization under somatosensory evoked potential (SSEP) and motor evoked potential (MEP) monitoring in preparation for TES in treating spine tumors. The angiography findings, the embolized vessels, and the results are presented. RESULTS Five patients whose ages ranged from 33 to 75 years and who had thoracic spine tumors are reported. Four patients suffered from primary tumor and 1 patient had a metastatic tumor. Radicular arteries at the tumor level, 1 level above, and 1 level below were permanently occluded when SSEPs and MEPs were preserved during temporary occlusion. No complications were encountered during or after the angiography procedure and embolization. CONCLUSIONS Temporary occlusion with electrophysiological monitoring during preoperative angiography may improve the safety of permanent radicular artery occlusion, including the artery of Adamkiewicz in patients undergoing TES for the treatment of spine tumors.