Pseudarthrosis failures of anterior subaxial cervical spine fusion using a plate with a single screw per vertebral body: a case series.

INTRODUCTION: The UNIPLATE was developed to improve operative times and limit dissection at the lateral margins of the vertebral bodies. The distinguishing character of this plate is its thin design, which requires only one screw per vertebral level (monovertebral screw plate). Most cervical spine plates, in contrast, are designed for two screws per vertebral level (bivertebral screw plate). Limited reports of the biomechanical efficacy of the UNIPLATE are available, and to the authors' knowledge, this report represents the largest clinical study of its use. METHODS: This is a retrospective chart-review study of consecutively treated patients without previous cervical spine surgery undergoing anterior cervical diskectomy and fusion at one or two levels. The primary end point was symptomatic pseudarthrosis requiring revision surgery. Pseudarthrosis is defined as a failure of bony fusion on the operated level seen on thin-cut computed tomography scans performed on symptomatic patients. The rate of revision surgery caused by symptomatic pseudarthrosis was compared between patients undergoing one- and two-level fusion surgeries treated with UNIPLATE compared with other plates with two screws per vertebral level. The minimum follow-up was 18 months. RESULTS: A total of 162 patients were identified, including 125 patients with one-level fusion and 37 patients with two-level fusion surgery. The median follow-up period was 3.3 years. A significantly greater incidence (odds ratio 10.2, P = 0.042) of reoperation for symptomatic pseudarthrosis was noted for patients treated with the UNIPLATE (4 of 13, 31%) compared with patients treated with bivertebral screw plates (1 of 24, 2.5%). No significant difference in reoperation attributable to symptomatic pseudarthrosis was noted for different plating systems for one-level fusion surgeries. CONCLUSIONS: There is an increased rate of reoperation for symptomatic pseudarthrosis after anterior cervical diskectomy and fusion surgery with the use of a monovertebral screw semiconstrained plate, particularly in two-level fusion surgeries. Use of the UNIPLATE system has since been abandoned at our institution in favor of bivertebral screw plating systems.

Trends in neurosurgical complication rates at teaching vs nonteaching hospitals following duty-hour restrictions.

BACKGROUND: In 2003 the Accreditation Council for Graduate Medical Education implemented duty-hour restrictions for residents, with an unclear impact on patient care. OBJECTIVE: The authors hypothesize that implementation of duty-hour restrictions is not associated with decreased morbidity for neurosurgical patients. This hypothesis was tested with the Nationwide Inpatient Sample to examine inpatient complications associated with a common elective procedure, craniotomy for meningioma. METHODS: The Nationwide Inpatient Sample was queried for all patients admitted for elective craniotomy for meningioma from 1998 to 2008, excluding the year 2003. Each case was queried for common in-hospital postoperative complications. The complication rate was compared for 5-year epochs at teaching and nonteaching hospitals before (1998-2002) and after (2004-2008) the adoption of the Accreditation Council for Graduate Medical Education work-hour restriction. Multivariate analysis was performed to control for the effects of age and medical comorbidities. RESULTS: We identified 21177 patients who met inclusion criteria. We identified an effect of age, preexisting medical comorbidity, and timing of surgery on postoperative complication rates. At teaching hospitals, the complication rate increased from 14% to 16% (P < .001). In contrast, this increase was not mirrored at nonteaching hospitals, which saw a nearly constant postoperative complication rate of 15% from 1998 to 2002 and 15% for the years 2004 to 2008 (P = .979). This effect remained significant in a multivariate analysis including age and existing comorbidities as covariates (P = .016). CONCLUSION: In patients undergoing craniotomy for meningioma, postoperative complication rates increased at teaching hospitals, but not at nonteaching hospitals over the 5-year epochs before and after 2003.

The surgical skills laboratory residency interview: an enjoyable alternative.

PURPOSE: The authors aimed to trial an alternative interviewing strategy by inviting residency candidates to our surgical anatomy laboratory. Interviews were coincident with surgical dissection. The authors hypothesized that residency candidates hoping to match into a surgical subspecialty might enjoy this unconventional interviewing strategy, which would mimic an operating room experience. METHODS: On scheduled residency interview dates, formal, unstructured interviews were held with half of the neurosurgical faculty, and unstructured surgical skills laboratory-based interviews were held with the other half of the neurosurgical faculty. Interviews in the skills laboratory featured cases and corresponding surgical dissection guided by faculty. After the interview, the residency candidates were encouraged to complete an optional survey about their interview process. The survey results were pooled for analysis. RESULTS: Of 28 interviewed, 19 individuals responded to the survey. The survey respondents had favorable reviews of the all aspects of the interview process. When asked to report the most enjoyable part of the interview, all respondents listed the surgical skills laboratory. The average respondent scores for importance of the surgical skills laboratory interview (9.5 ± 1.1) compared with conventional interview with faculty (9.2 ± 1.0) or residents (9.1 ± 1.0) was not significantly different (p = 0.50, analysis of variance). CONCLUSIONS: The surgical skills laboratory interviews were reviewed favorably by the survey respondents. Nearly all respondents listed the surgical skills interview as the most enjoyable part of the interview experience. The authors advocate this residency interview strategy for surgical subspecialty residencies.

Increased rate of complications on a neurological surgery service after implementation of the Accreditation Council for Graduate Medical Education work-hour restriction.

OBJECT: The Accreditation Council for Graduate Medical Education instituted mandatory 80-hour work-week limitations in July 2003. The work-hour restriction was met with skepticism among the academic neurosurgery community and is thought to represent a barrier to teaching, ultimately compromising patient care. The authors hypothesize that the introduction of the mandatory resident work-hour restriction corresponds with an overall increase in morbidity rate. METHODS: This study compares the morbidity and mortality rates on an academic neurological surgery service before and after institution of the work-hour restriction. Complications are individually assessed at a monthly divisional conference by neurosurgical faculty and residents. A prospective database was commenced in July 2000 recording all complications, complications that were deemed to be potentially avoidable ("possibly preventable"), and complications that were deemed unavoidable. The incidence of morbidity and mortality from July 2000 to June 2003 is compared with the incidence from July 2003 to June 2006. RESULTS: The overall rate of morbidity and mortality increased from 103 to 114 per 1000 patients treated after institution of the work-hour restriction, although this increase was not statistically significant (χ(2)(1, N = 8546) = 2.6, p = 0.106). The morbidity rate increased from 70 to 89 per 1000 patients treated after institution of the work-hour restriction (χ(2)(1, N = 8546) = 10, p = 0.001). The overall mortality rate was diminished from 32 to 27 per 1000 patients treated after institution of the work-hour restriction (χ(2)(1, N = 8546) = 3.2, p = 0.075). Morbidities considered avoidable or possibly preventable were seen to increase from 56 to 66 per 1000 patients treated (χ(2)(1, N = 8546) = 5.7, p = 0.017). Avoidable or possibly preventable mortalities numbered 3 per 1000 patients treated, and this rate did not change after introduction of the work-hour restriction (χ(2)(1, N = 8546) = 0.08, p = 0.777). CONCLUSIONS: The morbidity rate on a neurological surgery service is increased after implementation of the work-hour restriction. Mortality rates remain unchanged.

Pneumosinus dilitans and meningioma: a case series and review of the literature.

Pneumosinus dilitans (PSD) is enlargement of the sinuses of the skull base and is frequently seen with meningiomas. Identifying PSD on imaging can assist with operative planning and preparation. Meningiomas associated with PSD are not more commonly high grade, and complete resection is frequently possible.

Safety of microvascular decompression for trigeminal neuralgia in the elderly. Clinical article.

OBJECT: Microvascular decompression (MVD) offers an effective and durable treatment for patients suffering from trigeminal neuralgia (TN). Because the disorder has a tendency to occur in older persons, the risks of surgical treatment in the elderly have been a topic of recent interest. To date, evidence derived from several small retrospective and a single prospective case series has suggested that age does not increase the complication rate associated with surgery. Using a large national database, the authors aimed to study the impact of age on in-hospital complications following MVD for TN. METHODS: Using the Nationwide Inpatient Sample (NIS) for the 10-year period from 1999 to 2008, the authors selected all patients who underwent MVD for TN. The primary outcome of interest was the in-hospital mortality rate. Secondary outcomes of interest were cardiac, pulmonary, thromboembolic, cerebrovascular, and wound complications as well as the duration of hospital stay, total hospital charges, and discharge location. An elderly cohort of patients was first defined as those 65 years of age and older and then redefined as those 75 years and older. RESULTS: A total of 3273 patients who underwent MVD for TN were identified, having a median age of 57 years. Within this sample, 31.5% were 65 years and older and 10.7% were 75 years and older. The in-hospital mortality rate was 0.68% for patients 65 years or older (p = 0.0087) and 1.16% for those 75 years or older (p = 0.0026). In patients younger than 65 years, the in-hospital mortality rate was 0.13% (3 deaths among 2241 patients). As analyzed using the chi-square test (for both 65 and 75 years as the age cutoff) and the Pearson rank correlation coefficient, the risk of cardiac, pulmonary, thromboembolic, and cerebrovascular complications was higher in older patients (that is, those 65 and older and those 75 and older), but the risks of wound complications and CNS infection were not. The risk of any in-hospital complication occurring in a patient 65 years and older was 7.36% (p < 0.0001) and 10.0% in those 75 years and older (p < 0.0001). There was no difference in the total hospital charges associated with age. The duration of the hospital stay was longer in older patients, and the likelihood of discharge home was lower in older patients. CONCLUSIONS: Microvascular decompression for TN in the elderly population remains a reasonable surgical option. However, based on data from a large national database, authors of the present study suggest that complications do tend to gradually increase in tandem with an advanced age. While age does not act as a risk factor in isolation, it may serve as a convenient surrogate for complication rates. The authors hope that this information can be of use in guiding older patients through decisions for the surgical treatment of TN.

Helmet use and reduction in skull fractures in skiers and snowboarders admitted to the hospital.

OBJECT: Helmet use has been associated with fewer hospital visits among injured skiers and snowboarders, but there remains no evidence that helmets alter the intracranial injury patterns. The authors hypothesized that helmet use among skiers and snowboarders reduces the incidence of head injury as defined by findings on head CT scans. METHODS: The authors performed a retrospective review of head-injured skiers and snowboarders at 2 Level I trauma centers in New England over a 6-year period. The primary outcome of interest was intracranial injury evident on CT scans. Secondary outcomes included the following: need for a neurosurgical procedure, presence of spine injury, need for ICU admission, length of stay, discharge location, and death. RESULTS: Of the 57 children identified who sustained a head injury while skiing or snowboarding, 33.3% were wearing a helmet at the time of injury. Of the helmeted patients, 5.3% sustained a calvarial fracture compared with 36.8% of the unhelmeted patients (p = 0.009). Although there was a favorable trend, there was no significant difference in the incidence of epidural hematoma, subdural hematoma, intraparenchymal hemorrhage, subarachnoid hemorrhage, or contusion in helmeted and unhelmeted patients. With regard to secondary outcomes, there were no significant differences between the 2 groups in percentage of patients requiring neurosurgical intervention, percentage requiring admission to an ICU, total length of stay, or percentage discharged home. There was no difference in the incidence of cervical spine injury. There was 1 death in an unhelmeted patient, and there were no deaths among helmeted patients. CONCLUSIONS: Among hospitalized children who sustained a head injury while skiing or snowboarding, a significantly lower number of patients suffered a skull fracture if they were wearing helmets at the time of the injury.

Venous air embolism: an unusual complication of atlantoaxial arthrodesis: case report.

STUDY DESIGN: A unique case of a patient with intraoperative venous air embolism (VAE) during atlantoaxial arthrodesis has been discussed. OBJECTIVE: To describe an uncommon complication of atlantoaxial arthrodesis, VAE. SUMMARY OF BACKGROUND DATA: Although several techniques for atlantoaxial arthrodesis have proven effective, lateral mass or pedicle screw constructs have been shown to have superior strength with acceptable morbidity. Placement of lateral mass or pedicle screws into the C1 or C2 vertebrae requires consideration of relevant local anatomy, including vascular and nervous structures. We present a rare complication of surgery in this anatomic distribution, VAE. To the authors' knowledge, there has been no similar report described. METHODS: A previously healthy 38-year-old man was found to have os odontoideum with atlantoaxial instability; arthrodesis was thus planned, with C1 lateral mass and C2 pedicle screws. Intraoperatively, during dissection of the C1-C2 joint capsule, the patient experienced a precipitous drop in blood pressure, end-tidal CO2, and oxygen saturation. Shortly thereafter, the patient was noted to be asystolic. RESULT: With suspicion for air embolus, the surgical field was flooded with irrigant, the incision closed with haste, and the patient rolled to the supine position. Cardiopulmonary resuscitation was initiated with return of pulse within minutes. A transesophageal echocardiogram was performed approximately 15 minutes after the onset of suspected air embolus, revealing increased atrial pressures consistent with VAE. Following echocardiogram, the patient was returned to prone position for completion of arthrodesis. Remaining surgery and arousal were uneventful. CONCLUSION: This is the first report of intraoperative VAE occurring with atlantoaxial arthrodesis. Enlarged venous anastomoses present at the atlantoaxial junction should be taken into consideration during surgical dissection, and the potential danger of VAE with atlantoaxial arthrodesis should be understood. With aggressive intraoperative treatment, this patient suffered no long-term complications.

Raymond M. P. Donaghy: a pioneer in microneurosurgery.

Raymond M. P. Donaghy was one of the true pioneers of modern neurosurgery. His restless dedication, innovation, and desire to humbly disseminate his knowledge facilitated the advancement of the field of microneurosurgery. Many of his trainees--most notably M. Gazi Yasargil--continued to advance the field, developing innovative microsurgical instruments and techniques. The history of microneurosurgery is incomplete without a glimpse at the life of this remarkable man.

Use of an artificial neural network to predict head injury outcome.

OBJECT: The authors describe the artificial neural network (ANN) as an innovative and powerful modeling tool that can be increasingly applied to develop predictive models in neurosurgery. They aimed to demonstrate the utility of an ANN in predicting survival following traumatic brain injury and compare its predictive ability with that of regression models and clinicians. METHODS: The authors designed an ANN to predict in-hospital survival following traumatic brain injury. The model was generated with 11 clinical inputs and a single output. Using a subset of the National Trauma Database, the authors "trained" the model to predict outcome by providing the model with patients for whom 11 clinical inputs were paired with known outcomes, which allowed the ANN to "learn" the relevant relationships that predict outcome. The model was tested against actual outcomes in a novel subset of 100 patients derived from the same database. For comparison with traditional forms of modeling, 2 regression models were developed using the same training set and were evaluated on the same testing set. Lastly, the authors used the same 100-patient testing set to evaluate 5 neurosurgery residents and 4 neurosurgery staff physicians on their ability to predict survival on the basis of the same 11 data points that were provided to the ANN. The ANN was compared with the clinicians and the regression models in terms of accuracy, sensitivity, specificity, and discrimination. RESULTS: Compared with regression models, the ANN was more accurate (p < 0.001), more sensitive (p < 0.001), as specific (p = 0.260), and more discriminating (p < 0.001). There was no difference between the neurosurgery residents and staff physicians, and all clinicians were pooled to compare with the 5 best neural networks. The ANNs were more accurate (p < 0.0001), more sensitive (p < 0.0001), as specific (p = 0.743), and more discriminating (p < 0.0001) than the clinicians. CONCLUSIONS: When given the same limited clinical information, the ANN significantly outperformed regression models and clinicians on multiple performance measures. While this paradigm certainly does not adequately reflect a real clinical scenario, this form of modeling could ultimately serve as a useful clinical decision support tool. As the model evolves to include more complex clinical variables, the performance gap over clinicians and logistic regression models will persist or, ideally, further increase.

A case-comparison study of the subdural evacuating port system in treating chronic subdural hematomas.

OBJECT: The Subdural Evacuating Port System (SEPS) was recently introduced as a novel method of treating chronic subdural hematomas (SDHs). This system is a variation of the existing twist-drill craniostomy methods for treating chronic SDH. Compared with craniotomy or bur hole treatment of chronic SDH, this system offers the possibility of treatment at bedside without general anesthesia. In comparison with existing twist-drill methods, the system theoretically offers the advantage of a hermetically closed system that can evacuate a hematoma without an intracranial catheter. METHODS: The authors performed a case-control study of all chronic SDHs treated at a single institution over a 5-year period and compared the efficacy and safety of the SEPS to bur hole evacuation. Patients were matched for age, injury mechanism, medical comorbidities, use of anticoagulation, and radiographic appearance of the SDH. The primary outcome of interest was the recurrence rate in each group, which was evaluated by radiographic evidence as well as the number of patients requiring a second procedure. Secondary outcomes examined were mortality, infection, acute hematoma formation, seizure, length of hospital stay, length of intensive care unit stay, and discharge location. RESULTS: The authors found that there were no appreciable differences in symptoms on presentation, existing comorbidities, home medications, or laboratory values between the treatment groups. The average Hounsfield units of preoperative CT scanning was similar in both groups. Radiographic recurrence was statistically similar between the SEPS group (25.9%) and the bur hole group (18.5%; p = 0.37). Although there was a trend toward higher reoperation rates in the SEPS group, the need for a subsequent procedure was also statistically similar between the SEPS group (25.9%) and the bur hole group (14.8%; p = 0.25). The mortality rate was not significantly different between the SEPS group (9.5%) and the bur hole group (4.8%; p = 0.50). The SEPS procedure provided a mean reduction in SDH thickness of 27.3% compared with 37.9% with bur hole (p = 0.05) when comparing the preoperative CT scan with the first postoperative CT scan. The percentage of reduction in SDH thickness when comparing the preoperative CT scan with the most recent postoperative CT scan was 40.5% in the SEPS group and 45.4% in the bur hole group (p = 0.31). CONCLUSIONS: The SEPS offers an alternative type of twist-drill craniostomy for the treatment of chronic SDH with a trend toward higher recurrence in our experience. The efficacy and safety of SEPS is similar to that of other twist-drill methods reported in the literature. In the authors' experience, the efficacy of this treatment as measured by radiographic worsening or the need for a subsequent procedure is statistically similar to that of bur hole treatment. There was no difference in mortality or other adverse outcomes associated with SEPS.

External carotid artery to middle cerebral artery bypass with the saphenous vein graft.

Patients with occlusive cerebrovascular disease who have failed maximal medical therapy, which consists of antiplatelet agents as well as maximizing modifiable risk factors such as blood pressure, cholesterol, smoking cessation, and obesity, and whose lesions are not amenable or have not responded to the more common vascular procedures (i.e., carotid endarterectomy or stenting) are considered candidates for an extracranial-intracranial bypass. Additionally, for a patient to be a candidate, he/she must have an adequate graft vessel. Typically, this vessel is the superficial temporal artery. However, oftentimes, the superficial temporal artery is an inadequate vessel or the patient requires a high-flow conduit. It is in these patients that use of the saphenous vein should be considered. In this report, we detail the technical aspects of performing an extracranial-intracranial bypass by using a saphenous vein graft.

External carotid artery to middle cerebral artery bypass with the saphenous vein graft.

Patients with occlusive cerebrovascular disease who have failed maximal medical therapy, which consists of antiplatelet agents as well as maximizing modifiable risk factors such as blood pressure, cholesterol, smoking cessation, and obesity, and whose lesions are not amenable or have not responded to the more common vascular procedures (i.e., carotid endarterectomy or stenting) are considered candidates for an extracranial-intracranial bypass. Additionally, for a patient to be a candidate, he/she must have an adequate graft vessel. Typically, this vessel is the superficial temporal artery. However, oftentimes, the superficial temporal artery is an inadequate vessel or the patient requires a high-flow conduit. It is in these patients that use of the saphenous vein should be considered. In this report, we detail the technical aspects of performing an extracranial-intracranial bypass by using a saphenous vein graft.

Hearing preservation with the transcrusal approach to the petroclival region.

OBJECTIVE: We studied the hearing results and outcomes after transcrusal craniotomy. STUDY DESIGN: We conducted a retrospective review. SETTING: This study was conducted at a tertiary care hospital. PATIENTS: We studied 10 consecutive patients, including two men and eight women, who underwent transcrusal craniotomy for petroclival masses or tumors. INTERVENTION: The intervention consisted of therapeutic removal of petroclival meningioma. MAIN OUTCOME MEASURE: The main outcome measure of this study was hearing preservation as measured by standard audiogram. RESULTS: There were six meningiomas, one eighth nerve schwannoma, one fifth nerve schwannoma, one chordoma, and one midbasilar artery aneurysm. Postoperative hearing was measured according to the AAOHNS criteria. Complications and further therapies were recorded. Postoperative hearing was measured in eight. The cochlear nerve was severed in one patient. One was unavailable for follow up. Eight patients retained hearing at or near preoperative levels, seven with SRT within 10 dB and speech discrimination within 10% of preoperative levels. Four patients presented with trigeminal symptoms, one with third nerve palsy and two with facial weakness. Postoperative deficits included fourth, sixth, seventh, and eighth nerve palsies in three patients. Complications included one wound infection, two cerebrospinal fluid leak, and two cases of meningitis, both of which were sterile. There were secondary procedures in five patients-three radiosurgery, two shunts, one tracheotomy, and one g-tube. CONCLUSIONS: Transcrusal craniotomy is a safe and effective approach to the petroclival region. Excellent hearing results can be expected with this technique.

Working area and angle of attack in three cranial base approaches: pterional, orbitozygomatic, and maxillary extension of the orbitozygomatic approach.

OBJECTIVE: This study was designed to quantify the operative exposure obtained in the pterional, orbitozygomatic, and modified orbitozygomatic with maxillary extension surgical approaches. METHODS: The pterional and orbitozygomatic approaches and a variation of the orbitozygomatic osteotomy that included an extra centimeter of bone resection in the inferior direction ("maxillary extension") were performed on cadaveric heads. For each surgical exposure, the working area was determined by using triangles defined with anatomic points. The "angle of attack" of the approaches for the same target point was determined with the use of a robotic microscope. RESULTS: The maximum allowable angle of attack was significantly greater with the orbitozygomatic approach (37.2 +/- 4.7 degrees) than that with the pterional approach (27.1 +/- 4.3 degrees) (P < 0.001). The angle of attack with the maxillary extension (42.0 +/- 4.9 degrees) was significantly greater than that with the orbitozygomatic approach (P < 0.001). The working areas were 281, 343, and 371 mm(2) for the pterional, orbitozygomatic, and maxillary extension approaches, respectively. The orbitozygomatic approach with maxillary extension had a significantly larger working area than the pterional approach (P = 0.011). CONCLUSION: Increments in bony removal open a wider angle in which to work more than they increase the actual amount of working area. Increasing the amount of bone removed by using an orbitozygomatic approach instead of a pterional approach converts a narrow space into a wide portal, allowing surgeons to work closer to the surgical target while decreasing the need for brain retraction. Extending the orbitozygomatic approach into the maxillary region also improves the exposure area and angle, but less significantly.