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Lee A. Tan, Ippei Takagi, and Harel Deutsch

Spinal epidural abscess (SEA) often requires prompt surgical decompression to prevent potential devastating neurological deficits. Dorsally located SEA usually can be evacuated via simple laminectomies. Ventral SEA often requires an anterior approach such as thoracotomy to achieve adequate exposure and decompression. We report a case of ventral thoracic SEA associated with discitis and osteomyelitis that was successfully treated via minimally invasive transpedicular approach. The patient had immediate and dramatic symptomatic improvement and was ambulatory on post-operative Day 1. The minimally invasive transpedicular approach avoids the surgical morbidity associated with anterior approach and is effective surgical alternative to treat ventral SEA.

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Lee A. Tan, David C. Straus, and Vincent C. Traynelis


The cervical interfacet spacer (CIS) is a relatively new technology that can increase foraminal height and area by facet distraction. These offer the potential to provide indirect neuroforaminal decompression while simultaneously enhancing fusion potential due to the relatively large osteoconductive surface area and compressive forces exerted on the grafts. These potential benefits, along with the relative ease of implantation during posterior cervical fusion procedures, make the CIS an attractive adjuvant in the management of cervical pathology. One concern with the use of interfacet spacers is the theoretical risk of inducing iatrogenic kyphosis. This work tests the hypothesis that interfacet spacers are associated with loss of cervical lordosis.


Records from patients undergoing posterior cervical fusion at Rush University Medical Center between March 2011 and December 2012 were reviewed. The FacetLift CISs were used in all patients. Preoperative and postoperative radiographic data were reviewed and the Ishihara indices and cervical lordotic angles were measured and recorded. Statistical analyses were performed using STATA software.


A total of 64 patients were identified in whom 154 cervical levels were implanted with machined allograft interfacet spacers. Of these, 15 patients underwent anterior-posterior fusions, 4 underwent anterior-posterior-anterior fusions, and the remaining 45 patients underwent posterior-only fusions. In the 45 patients with posterior-only fusions, a total of 110 levels were treated with spacers. There were 14 patients (31%) with a single level treated, 16 patients (36%) with two levels treated, 5 patients (11%) with three levels treated, 5 patients (11%) with four levels treated, 1 patient (2%) with five levels treated, and 4 patients (9%) with six levels treated. Complete radiographic data were available in 38 of 45 patients (84%). On average, radiographic follow-up was obtained at 256.9 days (range 48–524 days). There was no significant difference in the Ishihara index (5.76 preoperatively and 6.17 postoperatively, p = 0.8037). The analysis had 80% power to detect a change of 4.25 in the Ishihara index at p = 0.05. There was no significant difference in the preand postoperative cervical lordotic angles (35.6° preoperatively and 33.6° postoperatively, p = 0.2678). The analysis had 80% power to detect a 7° change in the cervical lordotic angle at p = 0.05. The ANOVA of the Ishihara index and cervical lordotic angle did not show a statistically significant difference in degree of change in cervical lordosis among patients with a different number of levels of CIS insertion (p = 0.25 and p = 0.96, respectively).


In the authors' experience of placing CISs in more than 100 levels, they found no evidence of significant loss of cervical lordosis. The long-term impacts of these implants on fusion rates and clinical outcomes (particularly radiculopathy and postoperative C-5 palsies) remain active areas of interest and fertile ground for further studies.

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Lee A. Tan, Manish K. Kasliwal, and Harel Deutsch

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Lee A. Tan, Carter S. Gerard, Vincent C. Traynelis, and Paul A. Anderson

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Manish K. Kasliwal, Lee A. Tan, and John E. O'Toole

Spinal metastases are the most common of spinal neoplasms and occur predominantly in an extradural location. Their appearance in an intradural location is uncommon and is associated with a poor prognosis. Cerebrospinal fluid dissemination accounts for a significant number of intradural spinal metastases mostly manifesting as leptomeningeal carcinomatoses or drop metastases from intracranial tumors. The occurrence of local tumor dissemination intradurally following surgery for an extradural spinal metastasis has not been reported previously. The authors describe 2 cases in which local intradural and intramedullary tumor recurrences occurred following resection of extradural metastases that were complicated by unintended durotomy. To heighten clinical awareness of this unusual form of local tumor recurrence, the authors discuss the possible etiology and clinical consequences of this entity.

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Lee A. Tan, Carter S. Gerard, Sumeet K. Ahuja, and Roham Moftakhar

Cerebellopontine angle (CPA) lesions account for up to 10% of all intracranial tumors. The most common CPA lesions are vestibular schwannomas (70–80%), meningiomas (10–15%) and epidermoid cysts (5%). CPA tumors are estimated to be the secondary cause for up to 9.9% patients with trigeminal neuralgia. We demonstrate a case of medically refractory trigeminal neuralgia caused by a CPA meningioma that was successfully treated via retrosigmoid approach. The patient had immediate and dramatic symptomatic improvement after surgery. Detailed surgical techniques of retrosigmoid craniotomy and tumor dissection are presented in high definition video with narration.

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Lee A. Tan, Ricardo B. Fontes, and Richard W. Byrne

Choroid plexus papillomas (CPP) are uncommon benign brain tumors that usually arise in the fourth ventricle in adults and lateral ventricles in children. Extraventricular CPPs are rare and can be found primarily in the cerebellopontine angle (CPA). We present a case of primary extraventricular CPP in the right CPA successfully resected with retrosigmoid approach. Detailed surgical techniques of retrosigmoid craniotomy and tumor dissection are presented in high definition video with narration.

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Lee A. Tan, Manish K. Kasliwal, and Vincent C. Traynelis

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Ricardo B. Fontes, Lee A. Tan, and John E. O'Toole

Spinal dural arteriovenous fistula (dAVF) is the most common vascular malformation of the spinal cord. Traditionally it is treated by the standard muscle-splitting midline approach with bilateral laminectomies extending from one level above to one level below the dAVF. We present a minimally invasive approach for ligation of dAVF with concurrent use of intraoperative indocyanine green (ICG) angiography. Minimally invasive watertight dural closure technique is also demonstrated and discussed. The minimally invasive approach with intraoperative ICG results in quicker recovery, early mobilization and shorter hospital stay compared to traditional open approach.

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Lee A. Tan, Carter S. Gerard, Paul A. Anderson, and Vincent C. Traynelis


Iatrogenic foraminal stenosis is a well-known complication in cervical spine surgery. Machined interfacet allograft spacers can provide a large surface area, which ensures solid support, and could potentially increase foraminal space. The authors tested the hypothesis that machined interfacet allograft spacers increase cervical foraminal height and area.


The C4–5, C5–6, and C6–7 facets of 4 fresh adult cadavers were exposed, and the cartilage was removed from each facet using customized rasps. Machined allograft spacers were tamped into the joints. The spines were scanned with the O-arm surgical imaging system before and after placement of the spacers. Two individuals independently measured foraminal height and area on obliquely angled sagittal images.


Foraminal height and area were significantly greater following placement of the machined interfacet spacers at all levels. The Pearson correlation between the 2 radiographic reviewers was very strong (r = 0.971, p = 0.0001), as was the intraclass correlation coefficient (ICC = 0.907, p = 0.0001). The average increase in foraminal height was 1.38 mm. The average increase in foraminal area was 18.4% (0.097 mm2).


Modest distraction of the facets using machined interfacet allograft spacers can increase foraminal height and area and therefore indirectly decompress the exiting nerve roots. This technique can be useful in treating primary foraminal stenosis and also for preventing iatrogenic foraminal stenosis that may occur when the initially nonlordotic spine is placed into lordosis either with repositioning after central canal decompression or with correction using instrumentation. These grafts may be a useful adjunct to the surgical treatment of cervical spine disease.