The Use of Tubular Retractors for Translaminar Discectomy for Cranially and Caudally Extruded Discs.

BACKGROUND: The conventional interlaminar approach is adequate for access to most disc herniations in lumbar spine surgery. The access to cranially and caudally migrated disc fragments, by conventional interlaminar fenestration, requires an extension of the fenestration with the potential destruction of the facet joint complex and consequent postsurgical instability. To describe the technique and results of the translaminar technique of targeted discectomy using tubular retractors for the surgical treatment of cranially and caudally extruded discs. MATERIALS AND METHODS: The study period extended from January 2008 to December 2014. All patients with lumbar herniated discs who failed conservative management were selected for surgery and underwent routine erect radiographs and magnetic resonance imaging (MRI) of the lumbar spine. The patients with cranially or caudally migrated discs were included in this study. The technique involves approaching migrated disc through an oval window (sculpted through an 18 mm tubular retractor using a burr) in the lamina precisely over the location of the migrated disc as predicted by the preoperative MRI (inferior lamina for inferior migration and superior lamina for superior migration). The perioperative parameters studied were operative time, blood loss, complications, Oswestry Disability Index (ODI), and visual analog scale (VAS) for leg pain before surgery and at last followup. In the study, 4 patients underwent a postoperative computed tomography-scan with a three-dimensional reconstruction to visualize the oval window and to rule out any pars fracture. All technical difficulties and complications were analyzed. RESULTS: 17 patients in the age group of 41-58 years underwent the translaminar technique of targeted discectomy. The migration of disc was cranial in 12 patients and caudal in 5 patients. Fourteen of the affected discs were at the L4-L5 level and three were at the L5-S1 level. The mean VAS (leg pain) scale improved from 8 to 1 and the mean ODI changed from 59.8 to 23.6. There were no intraoperative or postoperative complications encountered in this study. Furthermore, no patient in the present study required a conventional laminotomy or medial facetectomy. There was no evidence of iatrogenic pars injury or instability at the last followup. There were no recurrences till the last followup. CONCLUSIONS: The targeted translaminar approach preserves structures important for segmental spinal stability thus causing minimal anatomical disruption. This approach allows access to the extruded disc fragment and intervertebral disc space comparable to classical approaches.

Minimally Invasive Transforaminal Lumbar Interbody Fusion: An Attractive Option for Select Failed Backs.

STUDY DESIGN: Retrospective case series. PURPOSE: To compare minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) outcomes in primary and revision surgeries. OVERVIEW OF LITERATURE: Revision spinal fusion is often associated with an increased risk of approach-related complications. Patients can potentially benefit from the decreased approach-related morbidity associated with MI-TLIF. METHODS: Sixty consecutive MI-TLIF patients (20 failed back [Fa group], 40 primary [Pr group]) who underwent surgery between January 2011 and May 2012 were reviewed after Institutional Review Board approval to compare operative times, blood loss, complications, Oswestry Disability Index (ODI) scores, and Visual Analog Scale (VAS) scores for back and leg pain before surgery and at the last follow-up. RESULTS: Nineteen revision surgeries were compared with 36 primary surgeries. One failed back and four primary patients were excluded because of inadequate data. The mean follow-up times were 28 months and 24 months in the Pr and Fa groups, respectively. The mean pre- and postoperative ODI scores were 53.18 and 20.23 in the Pr group and 52.01 and 25.72 in the Fa group, respectively (ODI percentage change: Pr group, 60.36%±29.73%; Fa group, 69.32%±13.72%; p=0.304, not significant). The mean pre- and postoperative VAS scores for back pain were 4.77 and 1.75 in the Pr group and 4.1 and 2.0 in the Fa group, respectively, and the percentage changes were statistically significant (VAS back pain percentage change: Pr group, 48.78±30.91; Fa group, 69.32±13.72; p=0.027). The mean pre- and postoperative VAS scores for leg pain were 6.52 and 1.27 in the Pr group and 9.5 and 1.375 in the Fa group, respectively (VAS leg pain percentage change: Pr group, 81.07±29.39; Fa group, 75.72±15.26; p=0.538, not significant). There were no statistically significant differences in operative time and estimated blood loss and no complications. CONCLUSIONS: MI-TLIF outcomes were comparable between primary and revision surgeries. The inherent technique of MI-TLIF is particularly suitable for select failed backs because it exploits the intact paramedian corridor.

Posterior Cervicothoracic Instrumentation: Testing the Clinical Efficacy of Tapered Rods (Dual-Diameter Rods).

STUDY DESIGN: Prospective study. OBJECTIVE: To study the clinical efficacy of tapered rods in posterior cervicothoracic instrumentation. SUMMARY OF BACKGROUND DATA: The cervicothoracic spine is a junctional area with complex biomechanics. A variety of disorders affect this region, rendering it unstable. Numerous posterior constructs have been evaluated by in vitro biomechanical studies. There are no data available on the clinical efficacy of a screw-rod system utilizing tapered (dual-diameter) rods. This is the first study analyzing the efficacy of this system in clinical scenarios in the short term. MATERIALS AND METHODS: All consecutive patients with cervicothoracic junctional pathologies undergoing surgical treatment by posterior instrumentation utilizing tapered rods, between April 2007 and April 2012 were included in the study. The tapered rod tapers from a diameter of 5.5-3.5 mm to accommodate thoracic pedicle screws and lateral mass screws/pedicle screws of cervical spine, respectively. The cases were periodically followed up. Postoperative radiographs and computed tomography scans were analyzed. RESULTS: There were 14 cases, 11 males and 3 females. The etiology was tuberculosis in 7 cases, neoplasm in 5, and 1 each of trauma and deformity. Three patients required combined anterior and posterior surgeries and remaining 10 were managed by posterior-only procedures. The average follow-up was 28 months. Three patients died (surgically unrelated reasons) and 1 was lost to follow-up. Excluding 2 patients with neoplastic and traumatic etiologies, patients with neurological deficit had significant improvement. One patient had postoperative cerebrospinal fluid leak which was recognized and corrected subsequently. No biomechanical failure occurred in any of the patients. No intraoperative complications were noted. CONCLUSIONS: This study demonstrates that tapered rods are an excellent and a viable option to connect screws to stabilize cervicothoracic junction in the short term. This study complements the biomechanical studies previously reported.

Microendoscopic excision of C2 osteoid osteoma: a technical report.

STUDY DESIGN: Case report and description of technique. OBJECTIVE: To describe a microendoscopic posterior approach for excision of an osteoid osteoma of C2. SUMMARY OF BACKGROUND DATA: Microendoscopic techniques are widely used in the management of degenerative disorders of the spine. This is the first report of their use in the management of an osteoid osteoma via the posterior approach. METHODS: A 12-year-old-boy presented with left-sided neck pain of 3-month duration. Investigations revealed an osteoid osteoma of C2 lamina-lateral mass complex. The patient underwent a posterior microendoscopic excision using 18-mm diameter METRx system (Medtronic Sofamor Danek, Memphis, TN) of tubular retractors. A postoperative computed tomographic scan was done and preoperative and postoperative visual analogue scale and Neck Disability Index were evaluated. The patient was periodically followed up for 1 year. RESULTS: The postoperative computed tomographic scan revealed complete excision of the tumor. The visual analogue scale score for neck pain improved from 3/5 (preoperative) to 0/5 (postoperative) and Neck Disability Index from 33.33 (preoperative) to 0 (postoperative) at 1-year follow-up. CONCLUSION: Microendoscopic techniques can be extended to excise lesions of the spine. It is a safe procedure in experienced hands. The advantages are minimal morbidity, minimal postoperative pain and discomfort, less analgesic dependence, and better cosmesis. The authors recommend this technique for accessible lesions involving the spine.

Should we cross the cross-links?

STUDY DESIGN: Retrospective study. OBJECTIVE: To assess critically if cross-links are necessary adjuvants in posterior spinal constructs. SUMMARY OF BACKGROUND DATA: Although numerous biomechanical studies are available in the literature, there has been no clinical study that has evaluated the need for cross-links in clinical situations. METHODS: The spinal constructs of patients of varied etiology who underwent surgery between July 2007 and July 2011 without the usage of cross-links were evaluated. The immediate postoperative erect radiographs were compared with the erect radiographs at the last follow-up by 2 independent observers (spine fellows not involved in the management of the patients) critically for any rotational instability using the Nash-Moe technique of assessment of vertebral rotation as well as for any "parallelogram effect." The intraobserver and interobserver reliability was analyzed. RESULTS: There were 208 cases included in the study during the study period that satisfied the criteria. The total number of motion segments fused was 707 ranging from 1 to 15 involving various etiologies. The average follow-up was 15 months (12-36 mo). Barring one patient with a thoracolumbar fracture with rotational instability (AO [Arbeitsgemeinschaft für Osteosynthesefragen] type C) who had undergone a short-segment fixation, none of the cases demonstrated any rotational instability in the follow-up radiographs. Interestingly, the rotational instability (parallelogram effect) in that patient got corrected spontaneously once anterior reconstruction was performed. The intraobserver reliability was 100% and the interobserver reliability was 92.83%. This variability was in assessing the grade of vertebral rotation only; none of the levels had a change in rotation irrespective of variation in grade assessment in the final postoperative radiograph. CONCLUSION: This study concludes that use of cross-links in clinical practice may be avoidable. The derivations from biomechanical studies do not translate into clinical advantages. Eliminating the usage of cross-links reduces the operative time as well as the overall total hospital costs (a single cross-link may cost anywhere between $1500 and $2000 and surgeons tend to use single or multiple cross-links). Additionally, prominence of implants, corrosion, infection, implant failure, and pseudarthrosis are the other complications attributed to cross-links in the literature that can be eliminated by preventing their incorporation in spinal constructs. LEVEL OF EVIDENCE: N/A.

Pyridine-catalyzed stereoselective addition of acyclic 1,2-diones to acetylenic esters: synthetic and theoretical studies of an unprecedented rearrangement.

A systematic study of the addition of various 1,2-acyclic diones to activated acetylenic esters catalyzed by pyridine under mild conditions is described. This reaction provides a new protocol for the stereoselective synthesis of 1,2-diaroyl maleates. The exclusive formation of the cis isomer is especially noteworthy. This reaction occurs through the initial generation of a pyridine-dimethyl acetylene dicarboxylate zwitterion and its addition to the dione followed by an unprecedented benzoyl migration. Pyridine and substituted pyridines, such as 4-dimethylaminopyridine (DMAP) and 3-methoxypyridine, are the best catalysts and anhydrous 1,2-dimethoxyethane is found to be the solvent of choice. Structural, electronic, energetic and mechanistic details of the reaction are also revealed by density functional theory calculations, which strongly support the exclusive formation of the cis isomer of the 1,2-diaroyl maleates.

Congenital immunodeficiency disorder.

A 17 year old girl, a 9th standard student with history of recurrent pneumonia and soft tissue "cold abscesses" since neonatal period, presented with fever and cough with yellowish expectoration of 2 months duration. Her clinical and radiological finding along with elevated serum IgE level were consistent with the diagnosis of hyper immunoglobulin E syndrome or Job's syndrome.

Engaging zwitterions in carbon-carbon and carbon-nitrogen bond-forming reactions: A promising synthetic strategy.

An Account of carbon-carbon and carbon-nitrogen bond-forming reactions mediated by zwitterions generated by the addition of organic nucleophiles to activated unsaturated systems highlighting their synthetic potential is presented.

Engaging the pyridine-DMAD zwitterion in a novel strategy for the selective synthesis of highly substituted benzene and cyclopentenedione derivatives.

[reaction: see text] The pyridine-mediated reaction of dimethyl acetylenedicarboxylate and cyclobutene-1,2-diones affords selective access to either hexasubstituted benzene derivatives or cyclopentenedione derivatives depending on the concentration of pyridine.

Pyridine-catalyzed addition of diaryl-1,2-diones to dimethyl butynedioate leading to the formation of 1,2-diaroyl dimethyl maleates via an unprecedented rearrangement.

[reaction: see text] Pyridine catalyzes the reaction of 1,2-diaryl diones with dimethyl butynedioate to afford diaroyl maleates. This unprecedented rearrangement involves a unique benzoyl migration and proceeds with complete stereoselectivity.

A novel three-component reaction for the diastereoselective synthesis of 2H-pyrimido[2,1-a]isoquinolines via 1,4-dipolar cycloaddition.

[reaction: see text] The 1,4-dipole derived from isoquinoline and DMAD has been shown to react readily with N-tosylimines resulting in the diastereoselective synthesis of 2H-pyrimido[2,1-a]isoquinoline derivatives.