Surgical Strategy for Thoracic Disc Herniation: Analysis of 27 Cases Managed with Transthoracic Microdiscectomy, Lateral Extracavitary Approach and Arthropediculectomy

Abstract

IntroductionSurgical management of symptomatic thoracic disc herniation (TDH) has historically been problematic and technically demanding. Numerous surgical approaches currently used for the management of TDH can be categorized as posterolateral, lateral extracavitary and anterolateral. The latter group of approaches has optimal characteristics for the ventral exposure of the spinal channel and is best suited for resection of central or calcified TDH. However, posterolateral approaches are still widely used by neurosurgeons due to familiarity of the anatomy and less invasive characteristics. We present an analysis of eight year experience in the surgical management of TDH, utilizing transthoracic microdiscectomy (TTM), lateral extracavitary approach (LEA) and arthropediculectomy (APE), emphasizing the criteria for selecting an appropriate surgical method. Material and MethodsThe case series included 27 patients operated on between 2009 and 2015. The group was comprised of 16 men and 11 women, ages 41–66 (mean 52). Twenty four patients were diagnosed with thoracic myelopathy presenting as weakness in the lower limbs and (or) pelvic organ dysfunction, three patients presented with radiculopathy. Neuroimaging studies included CT and MRI in all patients. Six patients required MRI with contrast for the differential diagnosis. Indication for the operation were radiologically established compression of the spinal cord and it's neurovascular deravates by the TDH with the clinics of myeloradiculopathy Seven patients underwent TTM, six patients underwent LEA and fourteen patients were operated utilizing APE. Consideration factors in the selection of the surgical method included: 1. Neurological symptoms; 2. Type, size, location and lateralization of the TDH; 3. Consistency of the TDH; 4. The extent of the spinal cord compression with TDH; 5. Touch area between TDH and ventral aspect of the spinal cord; 6. Signs of TDH with dural adherence or transdural penetration; 7. Comorbidities and body habitus. Patients with lateral TDHs underwent APE. The ones with medial/mediolateral TDHs were stratified based upon the extent of TDH calcification. Patients with soft herniations were operated on via LEA. Those with heavily calcified, large or multiple TDHs were candidates for microdiscectomy via TTM. In patients with strict contraindications for thoracotomy, APE was performed. ResultsAnalysis of preoperative and final follow-up Frankel grades showed difference in the functional outcomes of patients after different surgical approaches. Of the 7 patients after TTM, the Frankel grade improved to E in 5 (74%), reached grade D in 2 (26%) and worsened in 0%. Results of LEA showed improvement to grade E in all 6 (100%) patients. Ten (72%) patients operated via APE improved to grade E, 3 (28%) patients improved to lesser degree. The approach associated morbidity in our series averaged 7% for TTM, 6,5% for LEA and 5,5% for APE (p > 0,05). ConclusionTTM allow excellent exposure of the mediolateral TDHs and is also the best choice for multiple/calcified TDHs in association with osteophytes. LEA provides more lateral access to TDH but entails larger osteoligamentous resection and blood loss, leading to high morbidity. APE is best suited for lateral, soft TDH or for medically compromised patients with contraindication for thoracotomy.