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Contralateral posterior interhemispheric approach to deep medial parietooccipital vascular malformations: surgical technique and results

Jan-Karl Burkhardt, Ethan A. Winkler, and Michael T. Lawton

OBJECTIVE

Deep medial parietooccipital arteriovenous malformations (AVMs) and cerebral cavernous malformations (CCMs) are traditionally resected through an ipsilateral posterior interhemispheric approach (IPIA), which creates a deep, perpendicular perspective with limited access to the lateral margins of the lesion. The contralateral posterior interhemispheric approach (CPIA) flips the positioning, with the midline positioned horizontally for retraction due to gravity, but with the AVM on the upper side and the approach from the contralateral, lower side. The aim of this paper was to analyze whether the perpendicular angle of attack that is used in IPIA would convert to a parallel angle of attack with the CPIA, with less retraction, improved working angles, and no significant increase in risk.

METHODS

A retrospective review of pre- and postoperative clinical and radiographic data was performed in 8 patients who underwent a CPIA.

RESULTS

Three AVMs and 5 CCMs were resected using the CPIA, with an average nidus size of 2.3 cm and CCM diameter of 1.7 cm. All lesions were resected completely, as confirmed on postoperative catheter angiography or MRI. All patients had good neurological outcomes, with either stable or improved modified Rankin Scale scores at last follow-up.

CONCLUSIONS

The CPIA is a safe alternative approach to the IPIA for deep medial parietooccipital vascular malformations that extend 2 cm or more off the midline. Contralaterality and retraction due to gravity optimize the interhemispheric corridor, the surgical trajectory to the lesion, and the visualization of the lateral margin, without resection or retraction of adjacent normal cortex. Although the falx is a physical barrier to accessing the lesion, it stabilizes the ipsilateral hemisphere while gravity delivers the dissected lesion through the transfalcine window. Patient positioning, CSF drainage, venous preservation, and meticulous dissection of the deep margins are critical to the safety of this approach.

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Rate of perioperative neurological complications after surgery for cervical spinal cord stimulation

Andrew K. Chan, Ethan A. Winkler, and Line Jacques

OBJECTIVE

Cervical spinal cord stimulation (cSCS) is used to treat pain of the cervical region and upper extremities. Case reports and small series have shown a relatively low risk of complication after cSCS, with only a single reported case of perioperative spinal cord injury in the literature. Catastrophic cSCS-associated spinal cord injury remains a concern as a result of underreporting. To aid in preoperative counseling, it is necessary to establish a minimum rate of spinal cord injury and surgical complication following cSCS.

METHODS

The Nationwide Inpatient Sample (NIS) is a stratified sample of 20% of all patient discharges from nonfederal hospitals in the United States. The authors identified discharges with a primary procedure code for spinal cord stimulation (ICD-9 03.93) associated with a primary diagnosis of cervical pathology from 2002 to 2011. They then analyzed short-term safety outcomes including the presence of spinal cord injury and neurological, medical, and general perioperative complications and compared outcomes using univariate analysis.

RESULTS

Between 2002 and 2011, there were 2053 discharges for cSCS. The spinal cord injury rate was 0.5%. The rates of any neurological, medical, and general perioperative complications were 1.1%, 1.4%, and 11.7%, respectively. There were no deaths.

CONCLUSIONS

In the largest series of cSCS, the risk of spinal cord injury was higher than previously reported (0.5%). Nonetheless, this procedure remains relatively safe, and physicians may use these data to corroborate the safety of cSCS in an appropriately selected patient population. This may become a key treatment option in an increasingly opioid-dependent, aging population.

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Letter to the Editor. Shunt dependency following aSAH

Ayhan Kanat

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Perioperative morbidity and mortality after lumbar trauma in the elderly

Ethan A. Winkler, John K. Yue, Harjus Birk, Caitlin K. Robinson, Geoffrey T. Manley, Sanjay S. Dhall, and Phiroz E. Tarapore

OBJECT

Traumatic fractures of the thoracolumbar spine are common injuries, accounting for approximately 90% of all spinal trauma. Lumbar spine trauma in the elderly is a growing public health problem with relatively little evidence to guide clinical management. The authors sought to characterize the complications, morbidity, and mortality associated with surgical and nonsurgical management in elderly patients with traumatic fractures of the lumbar spine.

METHODS

Using the National Sample Program of the National Trauma Data Bank, the authors performed a retrospective analysis of patients ≥ 55 years of age who had traumatic fracture to the lumbar spine. This group was divided into middle-aged (55–69 years) and elderly (≥ 70 years) cohorts. Cohorts were subdivided into nonoperative, vertebroplasty or kyphoplasty, noninstrumented surgery, and instrumented surgery. Univariate and multivariable analyses were used to characterize and identify predictors of medical and surgical complications, mortality, hospital length of stay, ICU length of stay, number of days on ventilator, and hospital discharge in each subgroup. Adjusted odds ratios, mean differences, and associated 95% CIs were reported. Statistical significance was assessed at p < 0.05, and the Bonferroni correction for multiple comparisons was applied for each outcome analysis.

RESULTS

Between 2003 and 2012, 22,835 people met the inclusion criteria, which represents 94,103 incidents nationally. Analyses revealed a similar medical and surgical complication profile between age groups. The most prevalent medical complications were pneumonia (7.0%), acute respiratory distress syndrome (3.6%), and deep venous thrombosis (3%). Surgical site infections occurred in 6.3% of cases. Instrumented surgery was associated with the highest odds of each complication (p < 0.001). The inpatient mortality rate was 6.8% for all subjects. Multivariable analyses demonstrated that age ≥ 70 years was an independent predictor of mortality (OR 3.16, 95% CI 2.77–3.60), whereas instrumented surgery (multivariable OR 0.38, 95% CI 0.28–0.52) and vertebroplasty or kyphoplasty (OR 0.27, 95% CI 0.17–0.45) were associated with decreased odds of death. In surviving patients, both older age (OR 0.32, 95% CI 0.30–0.34) and instrumented fusion (OR 0.37, 95% CI 0.33–0.41) were associated with decreased odds of discharge to home.

CONCLUSIONS

The present study confirms that lumbar surgery in the elderly is associated with increased morbidity. In particular, instrumented fusion is associated with periprocedural complications, prolonged hospitalization, and a decreased likelihood of being discharged home. However, fusion surgery is also associated with reduced mortality. Age alone should not be an exclusionary factor in identifying surgical candidates for instrumented lumbar spinal fusion. Future studies are needed to confirm these findings.

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Thoracic laminectomy and midline myelotomy for resection of a spinal ependymoma

Lea Scherschinski, Ethan A. Winkler, Charuta G. Furey, Timothy C. Gooldy, Joshua S. Catapano, and Michael T. Lawton

Spinal cord ependymomas comprise 25% of all intramedullary tumors and are typically treated with resection. A man in his mid-60s presented with imbalance and sensory deficits in both lower extremities, and a spinal thoracic intramedullary ependymoma spanning the levels T2 and T3 was diagnosed. After a laminectomy was performed, the tumor was microsurgically resected, and the patient demonstrated no neurological deficits on postoperative examination. Subsequent MRI showed complete resection of the tumor. This video showcases a thoracic intramedullary ependymoma resected using careful microdissection into the median raphe as a safe entry zone to preserve neurological function.

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Surgical selection and outcomes among elderly patients with brain arteriovenous malformations

Jan-Karl Burkhardt, Ethan A. Winkler, Joshua S. Catapano, Robert F. Spetzler, and Michael T. Lawton

OBJECTIVE

Studies of resection of brain arteriovenous malformations (AVMs) in the elderly population are scarce. This study examined factors influencing patient selection and surgical outcome among elderly patients.

METHODS

Patients 65 years of age and older who underwent resection of an unruptured or ruptured brain AVM treated by two surgeons at two centers were identified. Patient demographic characteristics, AVM characteristics, clinical presentation, and outcomes measured using the modified Rankin Scale (mRS) were analyzed. For subgroup analyses, patients were dichotomized into two age groups (group 1, 65–69 years old; group 2, ≥ 70 years old).

RESULTS

Overall, 112 patients were included in this study (group 1, n = 61; group 2, n = 51). Most of the patients presented with hemorrhage (71%), a small nidus (< 3 cm, 79%), and a low Spetzler-Martin (SM) grade (grade I or II, 63%) and were favorable surgical candidates according to the supplemented SM grade (supplemented SM grade < 7, 79%). A smaller AVM nidus was statistically significantly more likely to be present in patients with infratentorial AVMs (p = 0.006) and with a compact AVM nidus structure (p = 0.02). A larger AVM nidus was more likely to be treated with preoperative embolization (p < 0.001). Overall outcome was favorable (mRS scores 0–3) in 71% of the patients and was statistically independent from age group or AVM grading. Patients with ruptured AVMs at presentation had significantly better preoperative mRS scores (p < 0.001) and more favorable mRS scores at the last follow-up (p = 0.04) than patients with unruptured AVMs.

CONCLUSIONS

Outcomes were favorable after AVM resection in both groups of patients. Elderly patients with brain AVMs treated microsurgically were notable for small nidus size, AVM rupture, and low SM grades. Microsurgical resection is an important treatment modality for elderly patients with AVMs, and supplemented SM grading is a useful tool for the selection of patients who are most likely to achieve good neurological outcomes after resection.

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Incidence, classification, and treatment of angiographically occult intracranial aneurysms found during microsurgical aneurysm clipping of known aneurysms

Jan-Karl Burkhardt, Michelle H. Chua, Ethan A. Winkler, W. Caleb Rutledge, and Michael T. Lawton

OBJECTIVE

During the microsurgical clipping of known aneurysms, angiographically occult (AO) aneurysms are sometimes found and treated simultaneously to prevent their growth and protect the patient from future rupture or reoperation. The authors analyzed the incidence, treatment, and outcomes associated with AO aneurysms to determine whether limited surgical exploration around the known aneurysm was safe and justified given the known limitations of diagnostic angiography.

METHODS

An AO aneurysm was defined as a saccular aneurysm detected using the operative microscope during dissection of a known aneurysm, and not detected on preoperative catheter angiography. A prospective database was retrospectively reviewed to identify patients with AO aneurysms treated microsurgically over a 20-year period.

RESULTS

One hundred fifteen AO aneurysms (4.0%) were identified during 2867 distinct craniotomies for aneurysm clipping. The most common locations for AO aneurysms were the middle cerebral artery (60 aneurysms, 54.1%) and the anterior cerebral artery (20 aneurysms, 18.0%). Fifty-six AO aneurysms (50.5%) were located on the same artery as the known saccular aneurysm. Most AO aneurysms (95.5%) were clipped and there was no attributed morbidity. The most common causes of failed angiographic detection were superimposition of a large aneurysm (type 1, 30.6%), a small aneurysm (type 2, 18.9%), or an adjacent normal artery (type 3, 36.9%). Multivariate analysis identified multiple known aneurysms (odds ratio [OR] 3.45, 95% confidence interval [CI] 2.16–5.49, p < 0.0001) and young age (OR 0.981, 95% CI 0.965–0.997, p = 0.0226) as independent predictors of AO aneurysms.

CONCLUSIONS

Meticulous inspection of common aneurysm sites within the surgical field will identify AO aneurysms during microsurgical dissection of another known aneurysm. Simultaneous identification and treatment of these additional undiagnosed aneurysms can spare patients later rupture or reoperation, particularly in those with multiple known aneurysms and a history of subarachnoid hemorrhage. Limited microsurgical exploration around a known aneurysm can be performed safely without additional morbidity.

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Isolated abducens nerve palsy associated with subarachnoid hemorrhage: a localizing sign of ruptured posterior inferior cerebellar artery aneurysms

Jan-Karl Burkhardt, Ethan A. Winkler, George F. Lasker, John K. Yue, and Michael T. Lawton

OBJECTIVE

Compressive cranial nerve syndromes can be useful bedside clues to the diagnosis of an enlarging intracranial aneurysm and can also guide subsequent evaluation, as with an acute oculomotor nerve (cranial nerve [CN] III) palsy that is presumed to be a posterior communicating artery aneurysm and a surgical emergency until proven otherwise. The CN VI has a short cisternal segment from the pontomedullary sulcus to Dorello’s canal, remote from most PICA aneurysms but in the hemodynamic pathway of a rupturing PICA aneurysm that projects toward Dorello’s canal. The authors describe a cranial nerve syndrome for posterior inferior cerebellar artery (PICA) aneurysms that associates subarachnoid hemorrhage (SAH) and an isolated abducens nerve (CN VI) palsy.

METHODS

Clinical and radiological data from 106 surgical patients with PICA aneurysms (66 ruptured and 40 unruptured) were retrospectively reviewed. Data from a group of 174 patients with other aneurysmal SAH (aSAH) were analyzed in a similar manner to control for nonspecific effects of SAH. Univariate statistical analysis compared incidence and risk factors associated with CN VI palsy in subarachnoid hemorrhage.

RESULTS

Overall, 13 (4.6%) of 280 patients had CN VI palsy at presentation, and all of them had ruptured aneurysms (representing 13 [5.4%] of the 240 cases of ruptured aneurysms). CN VI palsies were observed in 12 patients with ruptured PICA aneurysms (12/66 [18.1%]) and 1 patient with other aSAH (1/174 [0.1%], p < 0.0001). PICA aneurysm location in ruptured aneurysms was an independent predictor for CN VI palsy on multivariate analysis (p = 0.001). PICA aneurysm size was not significantly different in patients with or without CN VI palsy (average size 4.4 mm and 5.2 mm, respectively). Within the PICA aneurysm cohort, modified Fisher grade (p = 0.011) and presence of a thick cisternal SAH (modified Fisher Grades 3 and 4) (p = 0.003) were predictors of CN VI palsy. In all patients with ruptured PICA aneurysms and CN VI palsy, dome projection and presumed direction of rupture were directed toward the ipsilateral and/or contralateral Dorello’s canal, in agreement with laterality of the CN palsy. In patients with bilateral CN VI palsies, a medial projection with extensive subarachnoid blood was observed near bilateral canals.

CONCLUSIONS

This study establishes a localizing connection between an isolated CN VI palsy, SAH, and an underlying ruptured PICA aneurysm. CN VI palsy is an important clinical sign in aSAH and when present on initial clinical presentation may be assumed to be due to ruptured PICA aneurysms until proven otherwise. The deficit may be ipsilateral, contralateral, or bilateral and is determined by the direction of the aneurysm dome projection and extent of subarachnoid bleeding toward Dorello’s canal, rather than by direct compression.

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Microsurgical resection of brain arteriovenous malformations in the elderly: outcomes analysis and risk stratification

Jan-Karl Burkhardt, George F. Lasker, Ethan A. Winkler, Helen Kim, and Michael T. Lawton

OBJECTIVE

Few outcomes studies have been published on microsurgical resection of arteriovenous malformations (AVMs) in elderly patients, and most are limited by a small sample size and the heterogeneous application of treatment modalities. This study aimed to determine whether functional outcomes at last follow-up (LFU) in patients 60 years or older differed when stratified by age.

METHODS

Patients 60 years or older (n = 104) who had undergone microsurgical AVM resection (total, n = 72; 60–65 years, n = 35; and > 65 years, n = 37) or observation (n = 32) were identified from a prospective database. Age, sex, Spetzler-Martin (SM) grade, supplemented SM grade, clinical presentation, AVM location, AVM-associated aneurysms, and functional outcome measured using the modified Rankin Scale (mRS score 0–2 [favorable] vs mRS score > 2 [unfavorable]) at LFU were analyzed.

RESULTS

AVM patients undergoing microsurgical resection were younger, had lower AVM grades, and were more likely to present with rupture. Overall outcome in the surgical group was favorable in 71% of the patients and was statistically significantly better in patients 60–65 years old (p = 0.039). In patients older than 65 years, outcome was dependent on SM grade and level of preexisting functional dependence. Patients with supplemented SM grades of greater than 6 points had favorable outcomes that were age dependent (p = 0.029). This difference was not observed in patients with lower supplemented SM grades or in those with low or high preoperative SM grades (SM grade ≤ 2 and grade ≥ 4, respectively).

CONCLUSIONS

This study demonstrates that favorable outcomes can be achieved with microsurgical resection of AVMs in elderly patients, with careful patient selection. Outcomes in more elderly patients (> 65 years of age) are more dependent on preoperative SM and supplemented SM grading than those in younger cohorts.

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Laminoplasty versus laminectomy with posterior spinal fusion for multilevel cervical spondylotic myelopathy: influence of cervical alignment on outcomes

Darryl Lau, Ethan A. Winkler, Khoi D. Than, Dean Chou, and Praveen V. Mummaneni

OBJECTIVE

Cervical curvature is an important factor when deciding between laminoplasty and laminectomy with posterior spinal fusion (LPSF) for cervical spondylotic myelopathy (CSM). This study compares outcomes following laminoplasty and LPSF in patients with matched postoperative cervical lordosis.

METHODS

Adults undergoing laminoplasty or LPSF for cervical CSM from 2011 to 2014 were identified. Matched cohorts were obtained by excluding LPSF patients with postoperative cervical Cobb angles outside the range of laminoplasty patients. Clinical outcomes and radiographic results were compared. A subgroup analysis of patients with and without preoperative pain was performed, and the effects of cervical curvature on pain outcomes were examined.

RESULTS

A total of 145 patients were included: 101 who underwent laminoplasty and 44 who underwent LPSF. Preoperative Nurick scale score, pain incidence, and visual analog scale (VAS) neck pain scores were similar between the two groups. Patients who underwent LPSF had significantly less preoperative cervical lordosis (5.8° vs 10.9°, p = 0.018). Preoperative and postoperative C2–7 sagittal vertical axis (SVA) and T-1 slope were similar between the two groups. Laminoplasty cases were associated with less blood loss (196.6 vs 325.0 ml, p < 0.001) and trended toward shorter hospital stays (3.5 vs 4.3 days, p = 0.054). The perioperative complication rate was 8.3%; there was no significant difference between the groups. LPSF was associated with a higher long-term complication rate (11.6% vs 2.2%, p = 0.036), with pseudarthrosis accounting for 3 of 5 complications in the LPSF group. Follow-up cervical Cobb angle was similar between the groups (8.8° vs 7.1°, p = 0.454). At final follow-up, LPSF had a significantly lower mean Nurick score (0.9 vs 1.4, p = 0.014). Among patients with preoperative neck pain, pain incidence (36.4% vs 31.3%, p = 0.629) and VAS neck pain (2.1 vs 1.8, p = 0.731) were similar between the groups. Similarly, in patients without preoperative pain, there was no significant difference in pain incidence (19.4% vs 18.2%, p = 0.926) and VAS neck pain (1.0 vs 1.1, p = 0.908). For laminoplasty, there was a significant trend for lower pain incidence (p = 0.010) and VAS neck pain (p = 0.004) with greater cervical lordosis, especially when greater than 20° (p = 0.011 and p = 0.018). Mean follow-up was 17.3 months.

CONCLUSIONS

For patients with CSM, LPSF was associated with slightly greater blood loss and a higher long-term complication rate, but offered greater neurological improvement than laminoplasty. In cohorts of matched follow-up cervical sagittal alignment, pain outcomes were similar between laminoplasty and LPSF patients. However, among laminoplasty patients, greater cervical lordosis was associated with better pain outcomes, especially for lordosis greater than 20°. Cervical curvature (lordosis) should be considered as an important factor in pain outcomes following posterior decompression for multilevel CSM.