When a dural defect is encountered during spine surgery, the dura mater must be reconstituted to minimize the occurrence of minor or major life-threatening sequelae. The neurosurgical literature lacks strategies for managing large dural defects encountered during surgery. The authors describe a 24-year-old man who developed cauda equina syndrome secondary to altered CSF flow in a large thoracolumbar arachnoid cyst. Surgical decompression and fenestration of the arachnoid cyst were performed, and the large dural defect was treated using a multilayer closure with collagen matrix, titanium mesh, and methylmethacrylate. At his 24-month postoperative follow-up, the patient had recovered full strength in his legs, and his sensory deficits and sexual dysfunction had resolved. His incision had healed well, and there were no signs of pseudomeningocele. He had no additional positional headaches. The defect was managed effectively with this technique. Although this technique is not a first-line strategy for dural closure in the spine, it can be considered in challenging cases when large dural defects are not amenable to traditional closure techniques.
Matthew T. Neal, Randall J. Hlubek, Alexander E. Ropper, and U. Kumar Kakarla
Tyler S. Cole, Kaith K. Almefty, Jakub Godzik, Amy H. Muma, Randall J. Hlubek, Eduardo Martinez-del-Campo, Nicholas Theodore, U. Kumar Kakarla, and Jay D. Turner
Cervical spondylotic myelopathy (CSM) is the primary cause of adult spinal cord dysfunction. Diminished hand strength and reduced dexterity associated with CSM contribute to disability. Here, the authors investigated the impact of CSM severity on hand function using quantitative testing and evaluated the response to surgical intervention.
Thirty-three patients undergoing surgical treatment of CSM were prospectively enrolled in the study. An occupational therapist conducted 3 functional hand tests: 1) palmar dynamometry to measure grip strength, 2) hydraulic pinch gauge test to measure pinch strength, and 3) 9-hole peg test (9-HPT) to evaluate upper extremity dexterity. Tests were performed preoperatively and 6–8 weeks postoperatively. Test results were expressed as 1) a percentile relative to age- and sex-stratified norms and 2) achievement of a minimum clinically important (MCI) difference. Patients were stratified into groups (mild, moderate, and severe myelopathy) based on their modified Japanese Orthopaedic Association (mJOA) score. The severity of stenosis on preoperative MRI was graded by three independent physicians using the Kang classification.
The primary presenting symptoms were neck pain (33%), numbness (21%), imbalance (12%), and upper extremity weakness (12%). Among the 33 patients, 61% (20) underwent anterior approach decompression, with a mean (SD) of 2.9 (1.5) levels treated. At baseline, patients with moderate and low mJOA scores (indicating more severe myelopathy) had lower preoperative pinch (p < 0.001) and grip (p = 0.01) strength than those with high mJOA scores/mild myelopathy. Postoperative improvement was observed in all hand function domains except pinch strength in the nondominant hand, with MCI differences at 6 weeks ranging from 33% of patients in dominant-hand strength tests to 73% of patients in nondominant-hand dexterity tests. Patients with moderate baseline mJOA scores were more likely to have MCI improvement in dominant grip strength (58.3%) than those with low mJOA scores/severe myelopathy (30%) and high mJOA scores/mild myelopathy (9%, p = 0.04). Dexterity in the dominant hand as measured by the 9-HPT ranged from < 1 in patients with cord signal change to 15.9 in patients with subarachnoid effacement only (p = 0.03).
Patients with CSM achieved significant improvement in strength and dexterity postoperatively. Baseline strength measures correlated best with the preoperative mJOA score; baseline dexterity correlated best with the severity of stenosis on MRI. The majority of patients experienced MCI improvements in dexterity. Baseline pinch strength correlated with postoperative mJOA MCI improvement, and patients with moderate baseline mJOA scores were the most likely to have improvement in dominant grip strength postoperatively.
Jakub Godzik, Bernardo de Andrada Pereira, Anna G. U. Sawa, Jennifer N. Lehrman, Randall J. Hlubek, Brian P. Kelly, and Jay D. Turner
The objective of this study was to evaluate a novel connector design and compare it with traditional side connectors, such as a fixed-angle connector (FAC) and a variable-angle connector (VAC), with respect to lumbosacral stability and instrumentation strain.
Standard nondestructive flexibility tests (7.5 Nm) and compression tests (400 N) were performed using 7 human cadaveric specimens (L1–ilium) to compare range of motion (ROM) stability, posterior rod strain (RS), and sacral screw bending moment (SM). Directions of motion included flexion, extension, left and right lateral bending, left and right axial rotation, and compression. Conditions included 1) the standard 2-rod construct (2R); 2) the dual-tulip head (DTH) with 4-rod construct (4R); 3) FACs with 4R; and 4) VACs with 4R. Data were analyzed using repeated-measures ANOVA.
Overall, there were no statistically significant differences in ROM across the lumbosacral junction among conditions (p > 0.07). Compared with 2R, DTH and FAC significantly reduced RS in extension, left axial rotation, and compression (p ≤ 0.03). VAC significantly decreased RS compared with 2R in flexion, extension, left axial rotation, right axial rotation, and compression (p ≤ 0.03), and significantly decreased RS compared with DTH in extension (p = 0.02). DTH was associated with increased SM in left and right axial rotation compared with 2R (p ≤ 0.003) and in left and right lateral bending and left and right axial rotation compared with FAC and VAC (p ≤ 0.02). FAC and VAC were associated with decreased SM compared with 2R in right and left lateral bending (p ≤ 0.03).
RS across the lumbosacral junction can be high. Supplemental rod fixation with DTH is an effective strategy for reducing RS across the lumbosacral junction. However, the greatest reduction in RS and SM was achieved with a VAC that allowed for straight (uncontoured) accessory rod placement.
Michael R. Levitt, Randall J. Hlubek, Karam Moon, M. Yashar S. Kalani, Peter Nakaji, Kris A. Smith, Andrew S. Little, Kerry Knievel, Jane W. Chan, Cameron G. McDougall, and Felipe C. Albuquerque
Cerebral venous pressure gradient (CVPG) from dural venous sinus stenosis is implicated in headache syndromes such as idiopathic intracranial hypertension (IIH). The incidence of CVPG in headache patients has not been reported.
The authors reviewed all cerebral venograms with manometry performed for headache between January 2008 and May 2015. Patient demographics, headache etiology, intracranial pressure (ICP) measurements, and radiographic and manometric results were recorded. CVPG was defined as a difference ≥ 8 mm Hg by venographic manometry.
One hundred sixty-four venograms were performed in 155 patients. There were no procedural complications. Ninety-six procedures (58.5%) were for patients with IIH. The overall incidence of CVPG was 25.6% (42 of 164 procedures): 35.4% (34 of 96 procedures) in IIH patients and 11.8% (8 of 68 procedures) in non-IIH patients. Sixty procedures (36.6%) were performed in patients with preexisting shunts. Seventy-seven patients (49.7%) had procedures preceded by an ICP measurement within 4 weeks of venography, and in 66 (85.7%) of these patients, the ICP had been found to be elevated. CVPG was seen in 8.3% (n = 5) of the procedures in the 60 patients with a preexisting shunt and in 0% (n = 0) of the 11 procedures in the 77 patients with normal ICP (p < 0.001 for both). Noninvasive imaging (MR venography, CT venography) was assessed prior to venography in 112 (68.3%) of 164 cases, and dural venous sinus abnormalities were demonstrated in 73 (65.2%) of these cases; there was a trend toward CVPG (p = 0.07). Multivariate analysis demonstrated an increased likelihood of CVPG in patients with IIH (OR 4.97, 95% CI 1.71–14.47) and a decreased likelihood in patients with a preexisting shunt (OR 0.09, 95% CI 0.02–0.44).
CVPG is uncommon in IIH patients, rare in those with preexisting shunts, and absent in those with normal ICP.