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Adam S. Kanter and Praveen V. Mummaneni

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H. Michael Keyoung, Adam S. Kanter and Praveen V. Mummaneni

✓There are many potential risks associated with spinal deformity correction procedures including transient and/or permanent neurological deficits. Typically, neurological deficits caused by the surgical correction of spinal kyphosis occur acutely during surgery or immediately after surgery. Delayed postoperative neurological deficits are extremely rare.

The authors report a case of delayed neurological deficit that occurred 48 hours after surgical correction of thoracic hyperkyphosis. An 18-year-old man with myotonic dystrophy presented with a 110° T7–L1 kyphosis. The patient underwent an uneventful two-stage correction procedure of the hyperkyphotic deformity. First, anterior discectomies and fusion were performed from T-7 to L-1 using rib autograft, and all segmental vessels were preserved. Subsequently, on the same day, the patient underwent posterior Smith–Petersen osteotomies and T7–L2 pedicle screw fixation. Intact somatosensory and motor evoked potentials were maintained throughout both operations. Postoperatively, he remained neurologically intact without sequelae for nearly 48 hours. On postoperative Day 2, the patient developed delayed monoplegia of the left leg and sensory level loss below T-10.

Medical management enabled complete reversal of the patient's monoplegia and sensory loss. At 2-year follow-up, the patient had no adverse neurological sequelae.

In this case, a delayed postoperative neurological deficit occurred following spinal hyperkyphosis correction. The authors discuss the possible etiological mechanisms behind this complication and suggest strategies for its management.

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Adam S. Kanter, Michael Y. Wang and Praveen V. Mummaneni

Object

Patients with ankylosing spondylitis (AS) who present with cervical spine fractures represent a unique challenge to spine surgeons. These injuries often result in neurological deficits that necessitate early and aggressive surgical management with posterior and/or anterior fixation. The authors introduce a clinical problem-solving algorithm to assist in the surgical management of instability and deformity in this exigent patient population.

Methods

Thirteen patients with AS and fractures of the cervical spine were radiographically evaluated to determine if spinal realignment was obtainable with cervical manipulation or traction. Seven patients had flexible deformities that were stabilized with either anterior or posterior fixation only, and 6 patients had fixed deformities and required circumferential anterior–posterior instrumentation. All patients were observed for neurological outcome, radiographic evidence of bone fusion, and complications.

Results

With the use of the authors' treatment algorithm, all patients were able to achieve satisfactory spinal realignment and bone fusion; 92% of patients achieved postoperative stability or improvement in Nurick and modified Japanese Orthopaedic Association scale scores. One patient experienced neurological deterioration following surgery, and 1 patient died at an acute rehabilitative facility following discharge.

Conclusions

Patients with AS are highly susceptible to extensive neurological injury and spinal deformity after sustaining cervical fractures from even minor traumatic forces. These injuries are uniquely complex in nature and require considerable scrutiny and aggressive surgical management to optimize spinal stability and functional outcomes. The authors' clinical problem-solving algorithm will assist spine surgeons in providing optimal care in this difficult population.

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Vincent Y. Wang, Adam S. Kanter and Praveen V. Mummaneni

✓Ossified ligamentum flavum (OLF) in the thoracic spine is a rare cause of myelopathy, often presenting with progressive symptomatology over an extended period of time. Surgical decompression via wide laminectomy has been the mainstay of treatment for this symptomatic disease phenomenon, but complications such as kyphotic deformity have developed due to extensive bone removal and release of the posterior tension band. The authors present a case of OLF excised via a minimally invasive microsurgical approach in which an expandable tubular retractor system was used. This approach enables complete decompression of the spinal canal while minimizing nerve, vascular, and musculoskeletal disruption, thus maintaining the native biomechanical disposition of the intact vertebral column.

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John H. Chi, Sanjay S. Dhall, Adam S. Kanter and Praveen V. Mummaneni

Object

Thoracic disc herniations can be surgically treated with a number of different techniques and approaches. However, surgical outcomes comparing the various techniques are rarely reported in the literature. The authors describe a minimally invasive technique to approach thoracic disc herniations via a transpedicular route with the use of tubular retractors and microscope visualization. This technique provides a safe method to identify the thoracic disc space and perform a decompression with minimal paraspinal soft tissue disruption. The authors compare the results of this approach with clinical results after open transpedicular discectomy.

Methods

The authors performed a retrospective cohort study comparing results in 11 patients with symptomatic thoracic disc herniations treated with either open posterolateral (4 patients) or mini-open transpedicular discectomy (7 patients). Hospital stay, blood loss, modified Prolo score, and Frankel score were used as outcome variables.

Results

Patients who underwent mini-open transpedicular discectomy had less blood loss and showed greater improvement in modified Prolo scores (p = 0.024 and p = 0.05, respectively) than those who underwent open transpedicular discectomy at the time of early follow-up within 1 year of surgery. However, at an average of 18 months of follow-up, the Prolo score difference between the 2 surgical groups was not statistically significant. There were no major or minor surgical complications in the patients who received the minimally invasive technique.

Conclusions

The mini-open transpedicular discectomy for thoracic disc herniations results in better modified Prolo scores at early postoperative intervals and less blood loss during surgery than open posterolateral discectomy. The authors' technique is described in detail and an intraoperative video is provided.

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Stephen M. Pirris, Sanjay Dhall, Praveen V. Mummaneni and Adam S. Kanter

Surgical access to extraforaminal lumbar disc herniations is complicated due to the unique anatomical constraints of the region. Minimizing complications during microdiscectomies at the level of L5–S1 in particular remains a challenge. The authors report on a small series of patients and provide a video presentation of a minimally invasive approach to L5–S1 extraforaminal lumbar disc herniations utilizing a tubular retractor with microscopic visualization.

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Adam S. Kanter, David S. Bradford, David O. Okonkwo, Setti S. Rengachary and Praveen V. Mummaneni

Seven millennia of anthropological artifacts and historical tales reference human spinal deformity, its diagnosis, and treatment—many of the latter of which turned out to be worse than the deformity itself. From Hippocrates to Harrington to the 21st century, the literature base has expanded in exponential fashion to yield an imperfect but constantly improving body of evidence, experience, and understanding of this challenging disease phenomenon. This review details the pre-1990 innovations, whose failures and successes have equally contributed to the advancement and dissemination of the increasingly evidence-based field of spinal deformity.

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Fred C. Lam, Adam S. Kanter, David O. Okonkwo, James W. Ogilvie and Praveen V. Mummaneni

In the first part of this 2-part historical review, the authors outlined the early diagnostic and therapeutic strategies used in the management of spinal deformity. In this second part, they expand upon those early innovations and further detail the advances from 1990 to the modern era.

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The comprehensive anatomical spinal osteotomy and anterior column realignment classification

Presented at the 2018 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Juan S. Uribe, Frank Schwab, Gregory M. Mundis Jr., David S. Xu, Jacob Januszewski, Adam S. Kanter, David O. Okonkwo, Serena S. Hu, Deviren Vedat, Robert Eastlack, Pedro Berjano and Praveen V. Mummaneni

OBJECTIVE

Spinal osteotomies and anterior column realignment (ACR) are procedures that allow preservation or restoration of spine lordosis. Variations of these techniques enable different degrees of segmental, regional, and global sagittal realignment. The authors propose a comprehensive anatomical classification system for ACR and its variants based on the level of technical complexity and invasiveness. This serves as a common language and platform to standardize clinical and radiographic outcomes for the utilization of ACR.

METHODS

The proposed classification is based on 6 anatomical grades of ACR, including anterior longitudinal ligament (ALL) release, with varying degrees of posterior column release or osteotomies. Additionally, a surgical approach (anterior, lateral, or posterior) was added. Reliability of the classification was evaluated by an analysis of 16 clinical cases, rated twice by 14 different spine surgeons, and calculation of Fleiss kappa coefficients.

RESULTS

The 6 grades of ACR are as follows: grade A, ALL release with hyperlordotic cage, intact posterior elements; grade 1 (ACR + Schwab grade 1), additional resection of the inferior facet and joint capsule; grade 2 (ACR + Schwab grade 2), additional resection of both superior and inferior facets, interspinous ligament, ligamentum flavum, lamina, and spinous process; grade 3 (ACR + Schwab grade 3), additional adjacent-level 3-column osteotomy including pedicle subtraction osteotomy; grade 4 (ACR + Schwab grade 4), 2-level distal 3-column osteotomy including pedicle subtraction osteotomy and disc space resection; and grade 5 (ACR + Schwab grade 5), complete or partial removal of a vertebral body and both adjacent discs with or without posterior element resection. Intraobserver and interobserver reliability were 97% and 98%, respectively, across the 14-reviewer cohort.

CONCLUSIONS

The proposed anatomical realignment classification provides a consistent description of the various posterior and anterior column release/osteotomies. This reliability study confirmed that the classification is consistent and reproducible across a diverse group of spine surgeons.

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Michael Y. Wang, Stacie Tran, G. Damian Brusko, Robert Eastlack, Paul Park, Pierce D. Nunley, Adam S. Kanter, Juan S. Uribe, Neel Anand, David O. Okonkwo, Khoi D. Than, Christopher I. Shaffrey, Virginie Lafage, Gregory M. Mundis Jr., Praveen V. Mummaneni and the MIS-ISSG Group

OBJECTIVE

The past decade has seen major advances in techniques for treating more complex spinal disorders using minimally invasive surgery (MIS). While appealing from the standpoint of patient perioperative outcomes, a major impediment to adoption has been the significant learning curve in utilizing MIS techniques.

METHODS

Data were retrospectively analyzed from a multicenter series of adult spinal deformity surgeries treated at eight tertiary spine care centers in the period from 2008 to 2015. All patients had undergone a less invasive or hybrid approach for a deformity correction satisfying the following inclusion criteria at baseline: coronal Cobb angle ≥ 20°, sagittal vertical axis (SVA) > 5 cm, or pelvic tilt > 20°. Analyzed data included baseline demographic details, severity of deformity, surgical metrics, clinical outcomes (numeric rating scale [NRS] score and Oswestry Disability Index [ODI]), radiographic outcomes, and complications. A minimum follow-up of 2 years was required for study inclusion.

RESULTS

Across the 8-year study period, among 222 patients, there was a trend toward treating increasingly morbid patients, with the mean age increasing from 50.7 to 62.4 years (p = 0.013) and the BMI increasing from 25.5 to 31.4 kg/m2 (p = 0.12). There was no statistical difference in the severity of coronal and sagittal deformity treated over the study period. With regard to radiographic changes following surgery, there was an increasing emphasis on sagittal correction and, conversely, less coronal correction. There was no statistically significant difference in clinical outcomes over the 8-year period, and meaningful improvements were seen in all years (ODI range of improvement: 15.0–26.9). Neither were there statistically significant differences in major complications; however, minor complications were seen less often as the surgeons gained experience (p = 0.064). Operative time was decreased on average by 47% over the 8-year period.

Trends in surgical practice were seen as well. Total fusion construct length was unchanged until the last year when there was a marked decrease in conjunction with a decrease in interbody levels treated (p = 0.004) while obtaining a higher degree of sagittal correction, suggesting more selective but powerful interbody reduction methods as reflected by an increase in the lateral and anterior column resection techniques being utilized.

CONCLUSIONS

The use of minimally invasive methods for adult spinal deformity surgery has evolved over the past decade. Experienced surgeons are treating older and more morbid patients with similar outcomes. A reliance on selective, more powerful interbody approaches is increasing as well.