Henry E. Aryan

Birth and evolution of the football helmet.

OBJECTIVE:To review the advent and evolution of the football helmet through historical, physiological, and biomechanical analysis. METHODS:We obtained data from a thorough review of the literature. RESULTS:Significant correlation exists between head injuries and the advent of the football helmet in 1896, through its evolution in the early to mid-1900s, and regulatory standards for both helmet use and design and tackling rules and regulations. With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. Not only is the material used important, but the protective design also proves essential in head injury prevention. Competition among leading helmet manufacturers has benefited the ultimate goal of injury prevention. However, just as significant in decreasing the incidence and severity of head injury is the implementation of newer rules and regulations in teaching, coaching, and governing tackling techniques. CONCLUSION:Helmet use in conjunction with more stringent head injury guidelines and rules has had a tremendous impact in decreasing head injury severity in football. Modifications of current testing models may further improve helmet design and hence further decrease the incidence and severity of head injury sustained while playing football.

Safety and efficacy of dexmedetomidine in neurosurgical patients

Primary objective: Very little information regarding effects on ICP, CPP and the safety of dexmedetomidine in neurosurgical patients has been published. The objective of this study is to gather information on the dosage, sedative effects and adverse effects of dexmedetomidine in neurosurgical patients. Research design: The study design was retrospective and descriptive. Methods and procedures: Computerized data were collected from the records of 39 neurosurgical patients in the ICU who received dexmedetomidine between October 2001 and December 2004. MAP, SBP, DBP, HR, ICP and CPP were recorded. The parameter means and standard deviations were obtained and plotted against time. Experimental interventions: Dexmedetomidine, an alpha-2 agonist, provides adequate sedation without altering respiratory drive, while facilitating frequent neurological examinations. The FDA approved a dosage range for a loading infusion of 0.1 mcg kg−1infused over 10 minutes followed by 0.2–0.7 mcg kg−1 h−1continuous infusion for 24 hours. Main outcomes and results: A total of 39 patients were enrolled in the study; 26 men and 13 women. The mean age was 34 years. Of the patients enrolled in the study, 15 were successfully extubated with no adverse reactions while maintaining adequate sedation. Agitation was the predominant adverse reaction. Hypotension occurred in 10 patients. The mean CPP increased and the mean ICP decreased. The standard deviation for the means of the ICP and CPP were small and did not fluctuate as widely as the haemodynamic parameters. Conclusions: Dexmedetomidine can be a safe and effective sedative agent for neurosurgical patients. A loading infusion should be avoided and higher maintenance doses may be required to ensure adequate sedation. Further studies are necessary to establish an optimal dosage regimen.

ANALYSIS AND EVOLUTION OF HEAD INJURY IN FOOTBALL

OBJECTIVE:To review head injury in football through historical, anatomic, and physiological analysis. METHODS:We obtained data from a thorough review of the literature. RESULTS:The reported incidence of concussion among high school football players dropped from 19% in 1983 to 4% in 1999. During the 1997 Canadian Football League season, players with a previous loss of consciousness in football were 6.15 times more likely to experience a concussion than players without a previous loss of consciousness (P < 0.05). Players with a previous concussion in football were 5.10 times more likely to experience a concussion than players without a previous concussion (P = 0.0001). With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. CONCLUSION:Significant declines in both the incidence and severity of head injury have been observed. The enhanced safety records in football can be attributed to the application of more stringent tackling regulations as well as the evolving football helmet. The role of a neurosurgeon is critical in further head injury prevention and guidelines in sport.

Aneurysms in children: Review of 15 years experience

INTRODUCTION Intracranial aneurysms in children are rare. The location, size, age, and presentation in the young are markedly different from that of adults. The 15-year experience of the senior author in southern California is presented. METHODS All paediatric patients treated for cerebral aneurysm over a 15-year period were identified. Intraoperative and postoperative data were collected retrospectively from the medical records. The need for additional surgery as well as the incidence of complications including death, hemiparesis, seizures, memory disturbances, and the need for subsequent cerebrospinal fluid (CSF) diversion were identified. RESULTS Fifty children were identified (54 lesions). Subarachnoid haemorrhage was the most common mode of presentation with the average Hunt-Hess grade being I-II. The locations of the lesions were middle cerebral (10), internal carotid (8), anterior communicating (7), posterior cerebral (6), posterior communicating (5), pericallosal (4), anterior cerebral (3), choroidal (3), posterior inferior cerebellar (3), basilar (2), vertebral (2) and frontopolar (1) arteries. Clinical vasospasm was encountered in eight of our patients, but no cases were observed in those younger than nine years. Long-term outcome was excellent in 22 cases, good in 20 and poor in nine, with one death and two patients lost to follow-up. CONCLUSION Analysis of our data suggested a predilection for the posterior circulation compared to adults, larger size, more complex architecture, and a decreased incidence of clinical vasospasm in the younger age group. This series and a review of the literature suggest that aneurysmal disease in children may be distinct from that of adults.

Long-term biomechanical stability and clinical improvement after extended multilevel corpectomy and circumferential reconstruction of the cervical spine using titanium mesh cages.

Study Design Retrospective review of clinical case series. Objective We present our experience with extended (≥3 levels) anterior cervical corpectomy (EACC) and reconstruction. Summary of Background Data Multilevel cervical corpectomy has traditionally been associated with increased graft-related complications and worse clinical outcomes compared with single-level procedures. Data specifically regarding corpectomies across 3 or more levels remains limited. Methods Retrospective review of data on 20 patients who underwent anterior cervical corpectomies with titanium mesh cage reconstruction and supplemental posterolateral fixation across 3 or more levels of the cervical spine. Anteroposterior/lateral plain films were used to determine sagittal balance and cage subsidence. Fusion was defined as the lack of motion on flexion-extension radiographs. Patients underwent preoperative and postoperative clinical assessment using visual analog scores and Nurick grading. Results Surgery was performed for spondylotic myelopathy in 15 patients, osteomyelitis in 4, and fracture in 1. Corpectomies were performed across an average of 3.4 levels. Average follow-up was 33 months. Local autograft was used in all cases except osteomyelitis, where allograft was used instead. Sagittal balance was improved or maintained in all patients and was not related to number of corpectomy levels. An average of 30.2 degrees of kyphosis correction was achieved in 9 patients. All patients demonstrated radiographic evidence of fusion without significant cage subsidence and no cases of instrumentation failure. Improvement in pain and functional scores occurred in all cases. Conclusions Circumferential reconstruction using titanium mesh cages after EACC can provide appropriate, biomechanically stable fixation and allows for significant correction of preexisting kyphosis. Supplemental posterior instrumentation may limit delayed cage subsidence and loss of sagittal balance after this procedure. EACC and circumferential reconstruction seems to be an effective treatment for symptomatic degenerative, traumatic, or infectious pathology involving 3 or more levels of the anterior cervical spine.

Intramedullary spinal cord metastasis of lung adenocarcinoma presenting as Brown-Sequard syndrome.

BACKGROUND It is extremely rare for cancer to present first as an intramedullary spinal cord metastasis. Furthermore, because it is unlikely for spinal cord neoplasm to present acutely, an acute presentation may signify metastatic disease and should be considered in the initial differential diagnosis. METHODS The authors present a case of a 59-year-old man presenting with Brown-Sequard syndrome and in whom metastatic lung adenocarcinoma to the spinal cord was subsequently discovered. Review of the literature reveals this case to be one of only a very few where intramedullary tumor was the first manifestation of metastatic disease. RESULTS The mainstay of treatment for intramedullary spinal metastases remains steroids, radiation, and chemotherapy, though no well-designed study compares these modalities by long-term survival and functional results. This patient underwent local radiation and systemic chemotherapy following surgical resection. CONCLUSIONS This patient had no preoperative signs suggesting disease in other organs, making the diagnosis of lung adenocarcinoma metastatic to the intramedullary cord surprising, especially given the extremely rare incidence of spinal intramedullary metastatic disease. However, the patient had an acute presentation, uncommon for primary neoplasm, which may be an indication of metastatic disease.

Stabilization of anterior cervical spine with bioabsorbable polymer in one- and two-level fusions.

OBJECTIVEWe present our experience using a bioabsorbable polymer in the surgical management of one- and two-level degenerative disc disease of the cervical spine with anterior cervical discectomy and fusion. Twenty-six patients were treated at the University of California, San Diego Medical Center or the Veterans Affairs Medical Center in San Diego, CA. All cases were performed under the direction of a single neurosurgeon (WRT). METHODSA retrospective review of patients’ charts and imaging was performed to determine outcomes after anterior cervical spine operations. Specifically, we looked at the need for additional surgery, local reaction to the bioabsorbable polymer, fusion rate, and complications. Procedures involved the C3–C4, C4–C5, C5–C6, and/or C6–C7 levels, and fibular allograft was used in all but one case. The anterior cervical discectomy and fusion procedures with internal fixation were performed in 26 patients between March 2000 and November 2001. The patients were followed for up to 2 years after surgery (average, 14 mo). RESULTSRadiographic fusion was achieved in 25 (96.2%) of 26 patients. Only one instance of treatment failure was encountered that required additional surgery and the placement of a titanium plate. There were no clinical signs or symptoms of reaction to the bioabsorbable material. CONCLUSIONThe rates of fusion after single-level anterior cervical discectomy and fusion with internal fixation using bioabsorbable polymer and screws in this study match those using metallic implants, as previously reported in the literature, and are superior to those achieved with noninstrumented fusions. Preliminary results suggest that this newly available technology for anterior fusion is as effective in single-level disease as traditional titanium plating systems. The bioabsorbable material seems to be tolerated well by patients. A larger, randomized, controlled study is necessary to bring the results to statistical significance.

Gunshot wounds to the spine in adolescents.

OBJECTIVE:The incidence of spinal instability after penetrating gunshot wounds to the spine in adolescents is unknown. We describe our experience over a 15-year period. METHODS:Hospital records were reviewed retrospectively. After injury and emergency care, patients were transferred to a rehabilitation facility. Examinations were completed using the American Spinal Injury Association and Frankel scales on admission, discharge, and 6 and 12 months after injury. Severity of injury was described by: 1) degree of neurological damage, 2) degree of preserved neurological function, and 3) presence of instability. RESULTS:Sixty patients were identified with a mean age 15.6 years (± 2.7 yr). Twelve patients had cervical, 31 thoracic, and 17 lumbosacral injuries. No operative treatments were used in their care. Thirty-four patients had complete neurological deficits. Mean acute hospitalization was 21.1 days (± 22.8 d), and mean rehabilitation stay was 86.3 days (± 48.9 d), for a total hospitalization of 107.4 days (± 65.9 d). At 1 year, 19 patients were ambulatory and 53 were autonomous. Despite the presence of bony involvement in all, no evidence of spinal instability was noted on follow-up dynamic imaging. Even in two patients with apparent two-column disruption, no instability was noted. At 1-year follow-up, significant (nonfunctional) improvement was noted in the neurological examination (P < 0.0001). Improvements were most notable in those patients with cervical injuries, followed by thoracic and lumbar injuries. CONCLUSION:After penetrating gunshot wounds to the spine, patients at 1-year follow-up examinations have evidence of significant, but nonfunctional, improvement. No evidence of spinal instability was noted in this study, and no surgical intervention was required.

Modified paramedian transpedicular approach and spinal reconstruction for intradural tumors of the cervical and cervicothoracic spine: clinical experience.

Study Design. Retrospective review of the medical, radiographic, surgical, and postoperative records of patients who underwent resection of multilevel intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spine via a modified paramedian transpedicular approach at the University of California, San Francisco, between 2003 and 2005. Objective. To assess the surgical, clinical, and radiographic outcomes of using the modified paramedian transpedicular approach to resect ventral intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spine. Summary of Background Data. A common theme of skull-base surgery for many years has been to remove the bone rather than retract neural elements. In this report, we demonstrate some possible advantages of taking a “spine-base” approach for resecting intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spinal canal, and present our clinical experience. Methods. All medical, surgical, and radiologic records were retrospectively reviewed. Clinical outcome was assessed for disability via the Neck Disability Index and for pain via the visual analog scale. Results. Fourteen patients (4 males and 10 females, average age 39.6 years, range 20–62) with intradural extramedullary spinal cord tumors involving multiple levels of the anterior cervical and cervicothoracic spine were identified. All patients presented with pain and/or radiculomyelopathy attributed to a ventral intradural extramedullary spinal cord tumor of the cervical or cervicothoracic spine that was resected via the modified paramedian transpedicular approach with partial dorsal corpectomy and posterior spinal reconstruction. The average follow-up period was 14.6 months (range 5–30). Gross total resection was achieved in all cases, and no patient required additional surgery via an anterior approach for residual tumor. Conclusions. The modified paramedian transpedicular approach with partial dorsal corpectomy we describe here is a variation of traditional thoracic posterolateral transpedicular extracavitary approaches and offers direct access to lesions of the ventral cervicothoracic spinal canal. This approach avoids the morbidity of anterior transcervical, transoral, or transthoracic procedures, while providing a view of the entire ventral cervicothoracic canal, and can be performed safely and effectively in select patients.

Stem cell-mediated regeneration of the intervertebral disc: cellular and molecular challenges

Regenerative medicine and stem cells hold great promise for intervertebral disc (IVD) disease. The therapeutic implications of utilizing stem cells to repair degenerated discs and treat back pain are highly anticipated by both the clinical and scientific communities. Although the avascular environment of the IVD poses a challenge for stem cell-mediated regeneration, neuroprogenitor cells have been discovered within degenerated discs, allowing scientists to revisit the hostile environment of the IVD as a target for stem cell therapy. Issues now under investigation include the timing of cell delivery and manipulation of stem cells to make them more efficient and adaptive in the IVD niche. This review covers the mechanisms underlying disc degeneration as well as the molecular and cellular challenges involved in directing stem cells to the desired cell type for intradiscal transplantation.