Real-time navigation guidance with intraoperative CT imaging for pedicle screw placement using an augmented reality head-mounted display: a proof-of-concept study.

OBJECTIVE: Augmented reality (AR) has the potential to improve the accuracy and efficiency of instrumentation placement in spinal fusion surgery, increasing patient safety and outcomes, optimizing ergonomics in the surgical suite, and ultimately lowering procedural costs. The authors sought to describe the use of a commercial prototype Spine AR platform (SpineAR) that provides a commercial AR head-mounted display (ARHMD) user interface for navigation-guided spine surgery incorporating real-time navigation images from intraoperative imaging with a 3D-reconstructed model in the surgeon's field of view, and to assess screw placement accuracy via this method. METHODS: Pedicle screw placement accuracy was assessed and compared with literature-reported data of the freehand (FH) technique. Accuracy with SpineAR was also compared between participants of varying spine surgical experience. Eleven operators without prior experience with AR-assisted pedicle screw placement took part in the study: 5 attending neurosurgeons and 6 trainees (1 neurosurgical fellow, 1 senior orthopedic resident, 3 neurosurgical residents, and 1 medical student). Commercially available 3D-printed lumbar spine models were utilized as surrogates of human anatomy. Among the operators, a total of 192 screws were instrumented bilaterally from L2-5 using SpineAR in 24 lumbar spine models. All but one trainee also inserted 8 screws using the FH method. In addition to accuracy scoring using the Gertzbein-Robbins grading scale, axial trajectory was assessed, and user feedback on experience with SpineAR was collected. RESULTS: Based on the Gertzbein-Robbins grading scale, the overall screw placement accuracy using SpineAR among all users was 98.4% (192 screws). Accuracy for attendings and trainees was 99.1% (112 screws) and 97.5% (80 screws), respectively. Accuracy rates were higher compared with literature-reported lumbar screw placement accuracy using FH for attendings (99.1% vs 94.32%; p = 0.0212) and all users (98.4% vs 94.32%; p = 0.0099). The percentage of total inserted screws with a minimum of 5° medial angulation was 100%. No differences were observed between attendings and trainees or between the two methods. User feedback on SpineAR was generally positive. CONCLUSIONS: Screw placement was feasible and accurate using SpineAR, an ARHMD platform with real-time navigation guidance that provided a favorable surgeon-user experience.

Complications of interhemispheric transcallosal approach in children: review of 15 years experience.

OBJECTIVE: The interhemispheric transcallosal approach to deep-seated lesions in and around the ventricular system avoids cortical manipulation and injury. Few case series discuss the morbidity associated with this approach. This study describes the 15-year experience of the senior author in Southern California. METHODS: All pediatric patients who have undergone interhemispheric, transcallosal resections of mass lesions over a 15-year period were identified. The surgical approach was uniform with respect to positioning of the patient. Intra-operative and post-operative data were collected retrospectively from the medical records. The need for bridging vein ligation as well as the incidence of hemiparesis, seizures, memory disturbances, and the need for subsequent cerebrospinal fluid (CSF) diversion were identified. RESULTS: Sixty-five patients were identified. The incidence of transient post-operative hemiparesis appeared to be higher in those patients who required ligation of one or two parasagittal veins (44.6% versus 18.5%) with no difference in long-term outcome. Nineteen percent (18.5%) of patients had post-operative seizures; however, no long-term seizure disorder was identified. Nine percent (9.2%) had reports of transient short-term memory deficits. Thirty-four percent (33.8%) of patients required secondary operative intervention for CSF diversion. The total complication rate, including need for CSF diversion, transient hemiparesis, infection, post-operative seizures, and memory disturbance was 36.9%. By 1 year, the total number of patients with persistent hemiparesis, memory disturbance, or seizures refractory to medication was 4 (6.2%). CONCLUSION: This series demonstrates that the interhemispheric transcallosal corridor is a versatile and safe approach in childhood, resulting in low post-operative permanent morbidity.

Prolonged Jackson-Pratt drainage in the management of lumbar cerebrospinal fluid leaks.

BACKGROUND: Cerebrospinal fluid (CSF) leak is a complication of spinal surgery. Intraoperative or postoperative identification of a CSF leak often results in wound healing complications, lumbar drain placement, and/or reoperation. These complications usually extend a patient's hospital stay, can be painful, and have their own associated risks. The authors describe a technique that may improve on traditional interventions by managing postoperative CSF leaks after lumbar instrumentation without an additional procedure or extended hospitalization. METHODS: A retrospective review of lumbar instrumentation cases performed by 5 attending surgeons from the Division of Neurosurgery, University of California at San Diego, was performed. In all, 184 charts were reviewed, spanning a 3-year period. There were 16 cases in which a dural tear and repair were carried out and subsequently treated with subfascial Jackson-Pratt (JP) drainage. Of those 16 cases, 8 patients were managed with prolonged JP drainage using the intraoperatively placed subfascial drain. Patients were discharged home on oral antibiotics according to the customary criteria with the JP drain in place and were instructed regarding proper drain maintenance. Jackson-Pratt drains were removed in clinic in a delayed fashion, approximately 10 to 17 days postoperatively. Patients were subsequently reevaluated at regular intervals for any persistent CSF leak. RESULTS: In the 8 cases reviewed, all patients were discharged in a time frame comparable to that of patients undergoing similar instrumentation in which no CSF leak was identified, or in whom a CSF leak was identified and repaired intraoperatively. No patients suffered complications arising from prolonged drain presence. No patients suffered from persistent CSF leak after drains were removed. CONCLUSION: Our study suggests that routine intraoperative subfascial JP drain placement aids in the early diagnosis of postoperative lumbar CSF leak. Primary closure of dural tear remains the standard of care. Furthermore, in select cases, prolonged JP drainage in the setting of postoperative CSF leak may be a useful technique for the treatment of these leaks.

The pathophysiologic mechanism of cerebellar mutism.

OBJECTIVE: Cerebellar mutism (CM) is a postoperative complication of mainly pediatric posterior fossa surgery. Multiple theories exist for explaining this phenomenon. We have made an attempt to further understand this entity given a particularly interesting case as it relates to multiple pathophysiologic pathways. METHODS: We have reviewed the details surrounding a particularly interesting case of CM. A retrospective analysis of this patient's clinical history and recovery is described. An extensive literature review has been performed in conjunction with an attempt to help elucidate details and a better understanding of CM. RESULTS: A thorough analysis of existing theories as to the pathophysiologic mechanism of CM has been performed as it relates to the details of this particular case. A case is described in which a child exhibiting CM abruptly improved and made a relatively quick recovery after the triggering of the melodic speech pathway by way of watching and beginning to sing along with a video. It appears that this incident involving a familiar song catalyzed various speech pathways, which apparently were in some state of shock. This phenomenon seems to be a temporary entity involving not only the mechanical coordination of speech production, but also the initiation of speech itself. CONCLUSIONS: Evidence exists for a pathophysiologic pathway for speech by way of coordinating phonation and articulation. In addition, there seems to exist a pathway by which the initiation of speech may be altered or halted by posterior fossa pathology, namely, vermian or dentate nuclear injury. In particular to this case, we found that the incidental appreciation of other forms of speech, melodic in this instance, may be the key to help stimulate and accelerate the recovery from CM.

Minimally disruptive decompression and transforaminal lumbar interbody fusion.

BACKGROUND: Posterior spinal procedures through tubular exposures have been described. However, tubes restrain visibility and require co-axial instrument manipulation, increasing difficulty and potentially compromising surgical results. An independent-blade retractor system overcomes the obstacles of working through a tube and has been used to perform minimally-disruptive decompression and instrumented tranforaminal lumbar interbody fusion (TLIF). PURPOSE: To evaluate the advantages to patient recovery and surgical efficacy of this technique. METHODS/RESULTS: Retrospective review of technique employing a minimally-disruptive approach to decompression and transforaminal lumber interbody fusion (TLIF). CONCLUSIONS: Minimally-disruptive decompression and instrumented TLIF can be performed in a safe and effective manner using an independent-blade retractor system. Relative to traditional-open techniques, surgical goals can be accomplished, but with the benefits of minimally-disruptive surgery.

Automated intraoperative EMG testing during percutaneous pedicle screw placement.

BACKGROUND: EMG screw testing has been shown to be sensitive and reliable in open spinal instrumentation cases. However, there is little evidence to show its applicability to percutaneous screw placement. PURPOSE: To demonstrate the utility of EMG testing in percutaneous techniques, where lack of direct visualization poses an added risk to nerve injury. STUDY DESIGN: Summary of intraoperative EMG results during percutaneous pedicle screw placement. METHODS: Percutaneous pedicle screws were placed in twenty patients (22 levels, 88 pedicles). The initial fluoroscopically-guided k-wires and the subsequent taps were insulated and stimulated via an automated EMG system. Low threshold values prompted repositioning of the pedicle trajectory. RESULTS: Four (5%) k-wires induced EMG thresholds less than 10mA, prompting repositioning. One was repositioned without improvement, but with improvement upon tapping. One k-wire with very low threshold (3mA) was repositioned with an improved result (13mA). In 78 pedicles (89%) the tap threshold was greater than the k-wire. CONCLUSIONS: EMG testing helps to identify suboptimal screw trajectories, allowing for early adjustment and confirmation of improved placement. Tapping often improved thresholds, perhaps by compressing the bone and creating a denser, more insulative pedicle wall. EMG testing may improve the safety of percutaneous screw techniques, where the pedicle cannot be visually inspected.

Extreme Lateral Interbody Fusion (XLIF): a novel surgical technique for anterior lumbar interbody fusion.

BACKGROUND: Minimally disruptive approaches to the anterior lumbar spine continue to evolve in a quest to reduce approach-related morbidity. A lateral retroperitoneal, trans-psoas approach to the anterior disc space allows for complete discectomy, distraction, and interbody fusion without the need for an approach surgeon. PURPOSE: To demonstrate the feasibility of a minimally disruptive lateral retroperitoneal approach and the advantages to patient recovery. METHODS/RESULTS: The extreme lateral approach (Extreme Lateral Interbody Fusion [XLIF]) is described in a step-wise manner. There have been no complications thus far in the author's first 13 patients. CONCLUSIONS: The XLIF approach allows for anterior access to the disc space without an approach surgeon or the complications of an anterior intra-abdominal procedure. Longer-term follow-up and data analysis are under way, but initial findings are encouraging.

Indirect revascularisation for paediatric moyamoya disease: the EDAMS technique.

Moyamoya disease can have devastating effects on paediatric patients as a result of cerebral ischaemia. Several direct and indirect surgical methods have been devised in order to facilitate revascularisation. Debate has long ensued about which methods are most efficacious and yet safe. The authors describe their experience with a straightforward method for performing the EDAMS (encephalo-duro-arterio-myo-synangiosis) technique.

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.

Endoscopic third ventriculostomy.

Among patients with idopathic aqueductal stenosis or impedance of cerebrospinal fluid (CSF) flow in the posterior fossa due to tumour, endoscopic fenestration of the floor of the third ventricle creates an alternative route for CSF flow to the subarachnoid space via the prepeduncular cistern. By reestablishing CSF flow, this procedure dissipates any pressure gradient on midline structures. This may obviate the need for traditional CSF shunt diversion techniques in such settings. Currently, endoscopic third ventriculostomy is indicated in approximately 25% of patients with hydrocephalus and can be performed instead of shunt placement. Appropriate patients are those with aqueductal stenosis (10%), obstructive tumours (10%), and obstructive cysts (5%). Additional recent data suggest the favorability of third ventriculostomy over shunt implantation in additional patient cohorts. Operative technique is discussed.

Subfrontal transbasal approach and technique for resection of craniopharyngioma.

A multimodality approach to craniopharyngioma, including minimally invasive stereotactic techniques, microsurgery, conventional radiotherapy, and radiosurgery has been recommended to tackle craniopharyngioma aggressively while minimizing harm to the patient. With all approaches, there are varying levels of risk for endocrinological morbidity, vascular complications, neuropsychological and behavioral disorders, neurocognitive disorders, and learning disabilities. Although many treatment options are available, total tumor resection remains the most commonly performed procedure for treatment of craniopharyngioma, and it is still believed to give the patient the greatest chance of having an independent and productive life with low risk of recurrences. The authors prefer the subfrontal transbasal approach for resection of these tumors, and they describe this approach and illustrate it with the accompanying figures.

Microsurgical keyhole middle fossa arachnoid cyst fenestration.

Microsurgical keyhole fenestration is a safe and effective surgical procedure for the treatment of middle fossa arachnoid cysts. This procedure can be performed with minimal morbidity through a keyhole craniotomy. Patient selection is crucial, as is knowledge of the surgical anatomy. We provide a detailed description of the technique, with Illustrations of the key aspects of the procedure.

Vertebral body granuloma of the cervical region after pencil injury.

OBJECTIVE AND IMPORTANCE: Granuloma formation has been reported as a rare complication of pencil lead injury. Insufficient data exist regarding pencil lead injuries of the cervical spine. We present the findings in an 18-year-old male patient with secondary granuloma formation after a penetrating transoral pencil injury. We suggest that imaging characteristics and a detailed history will assist with the diagnosis of such lesions. CLINICAL PRESENTATION AND INTERVENTION: The patient was an 18-year-old man who presented with cervical pain. His history included falling as a child while having a pencil in his mouth. T2-weighted imaging studies documented a 1- x 1-cm enhancing lesion posterior to the vertebral body at the C3 level. The patient underwent a C3 vertebrectomy, and specimens were notable for infection, pencil lead, and granuloma formation. CONCLUSION: In the evaluation of a potential granuloma or mass lesion of the cervical spine in a child or adolescent, the differential diagnosis may include a neoplasm. Although computed tomography is an ideal tool to detect foreign objects, including pencil leads, only awareness of the potential for pencil lead injuries and that pencil lead fragments may remain unrecognized on computed tomographic scans will assist the physician in diagnosing such injuries.

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

OBJECTIVE: We 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). METHODS: A 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). RESULTS: Radiographic 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. CONCLUSION: The 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.

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.

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.

Atypical presentation of C-7 radiculopathy.

OBJECT: The authors retrospectively reviewed the presenting symptomatology and 6-month outcome in 241 consecutive patients who underwent C6-7 anterior cervical discectomy (ACD) from an overall series of 1008 patients in whom the senior author performed one-level procedures. METHODS: In 28 (12%) of the 241 patients, the sole complaint was subscapular pain on the side ipsilateral to nerve root compression. In 11 patients (5%), the primary complaint was unilateral deep breast or chest pain. No patient experienced any of the traditional radicular signs involving C-7 such as numbness of the second or third digits, pain in the triceps, and/or atrophy or weakness of the triceps or pronator muscles. Of the 28 patients presenting with subscapular pain 238 (93%) of 241 experienced complete symptom relief within 6 months, and of the 11 who presented with chest pain complete relief or relief to the point of requiring nonnarcotic analgesic agents occurred in nine cases. CONCLUSIONS: Approximately 15% of patients with a C-7 radiculopathy are likely to present with atypical symptoms that, if persisting after nonsurgical therapy, will often resolve after ACD and fusion.

Fronto-orbital and cranial osteotomies with resorbable fixation using an endoscopic approach.

Over the past 3 years the authors have used modified minimally invasive endoscopic techniques in the surgical correction of craniosynostosis. For selected patients, these techniques offer an alternative to traditional techniques, minimizing postoperative morbidity and the need for cranial banding. Long-term follow-up will be needed to assess the ultimate efficacy of these techniques. Traditional techniques for repair of craniosynostosis have historically had a record of excellent aesthetic results with acceptable morbidity. Ultimately, each patient is best served by a customized plan, developed and implemented by a multidisciplinary team capable of the full range of techniques.

Two-year clinical and radiographic success of minimally invasive lateral transpsoas approach for the treatment of degenerative lumbar conditions.

BACKGROUND: The lateral transpsoas approach to interbody fusion is a less disruptive but direct-visualization approach for anterior/anterolateral fusion of the thoracolumbar spine. Several reports have detailed the technique, the safety of the approach, and the short term clinical benefits. However, no published studies to date have reported the long term clinical and radiographic success of the procedure. MATERIALS AND METHODS: The current study is a retrospective chart review of prospectively collected clinical and radiographic outcomes in 62 patients having undergone the Anterolateral transpsoas procedure at a single institution for anterior column stabilization as treatment for degenerative conditions, including degenerative disk disease, spondylolisthesis, scoliosis, and stenosis. Only patients who were a minimum of 2 years postoperative were included in this evaluation. Clinical outcomes measured included visual analog pain scales (VAS) and Oswestry disability index (ODI). Radiographic outcomes included identification of successful arthrodesis. RESULTS: Sixty-two patients were treated with lateral interbody fusion between 2003 and December 2006. Twenty-six patients (42%) were single-level, 13 (21%) 2-level, and 23 (37%) 3- or more levels. Forty-five (73%) included supplemental posterior pedicle fixation, 4 (6%) lateral fixation, and 13 (21%) were stand-alone. Pain scores (VAS) decreased significantly from preoperative to 2 years follow-up by 37% (P < .0001). Functional scores (ODI) decreased significantly by 39% from preoperative to 2 years follow-up (P < .0001). Clinical success by ODI-change definition was achieved in 71% of patients. Radiographic success was achieved in 91% of patients, with 1 patient with pseudarthrosis requiring posterior revision. CONCLUSION: The lateral transpsoas approach is similar to a traditional anterior lumbar interbody fusion, in that access is obtained through a retroperitoneal, direct-visualization exposure, and a large implant can be placed in the interspace to achieve disk height and alignment correction. The 2 years plus clinical and radiographic success rates are similar to or better than those reported for traditional anterior and posterior approach procedures, which, coupled with significant short-term benefits of minimal morbidity, make the lateral approach a safe and effective treatment option for anterior/anterolateral lumbar fusions.

Nonsyndromic craniosynostosis: current treatment options.

The significance and etiology of abnormal skull shape have been under investigation since ancient times. Nonsyndromic, or isolated, craniosynostosis predominates and is defined as suture fusion that creates functional impairments related to local effects of the fusion. The purpose of this article is to present our current approach to patients with nonsyndromic craniosynostosis, outlining the place of both open, conventional approaches and newer, minimally invasive, endoscopic assisted craniosynostosis correction.