Far lateral lumbar disc herniation part 1: Imaging, neurophysiology and clinical features

Far lateral lumbar disc herniations(FLLDH)represent a separate category of disc pathology which includes both intraforaminal and extraforaminal lumbar disc herniations,that are characterized by a peculiar clinical presentation,diagnostic and treatment modalities as compared to the more frequent median and paramedian disc hernias.Surgical treatment often represents the only effective weapon for the cure of this disease and over the years different approaches have been developed that can reach the region of the foramen or external to it,with different degrees of invasiveness.The diagnosis is more demanding and still underestimated as it requires a more detailed knowledge in the spine anatomy and dedicated radiological studies.Computerized tomography and in particular magnetic resonance imaging are the appropriate tools for the diagnosis of FLLDH.Despite the widespread use of these diagnostic tests,many cases of FLLDH are overlooked due to insufficiently detailed radiological examinations or due to the execution of exams not focused to the foraminal or the extraforaminal region.Neurophysiological studies represent a valid aid in the diagnostic classification of this pathology and in some cases they can facilitate the differential diagnosis with other types of radiculopathies.In the present study,a comprehensive review of the clinical presentation,epidemiology,radiological study and the neurophysiological aspects is presented.

Surgical treatment of the thoracic and thoracolumbar disc herniations through the posterior far lateral approach

Objective To evaluate the feasibility,safety and efficacy of surgical treatment of the thoracic and thoracolumbar disc herniations through the posterior far lateral approach.Methods From April 2005 to June 2010,24 consecutive patients

Clinical efficacy of three different minimally invasive procedures for far lateral lumbar disc herniation

Background Far lateral lumbar disc herniation （FLLDH） accounts for 2.6% to 11.7% of all lumbar herniated discs. Numerous surgical approaches have been described for treating this condition. The purpose of this study was to evaluate minimally invasive surgical techniques for the treatment of FLLDH. Methods From June 2000 to March 2006, 52 patients with FLLDH were treated with minimally invasive procedures. All patients were assessed by anteroposterior and lateral roentgenography and computed tomography （CT）. Some patients underwent myelography, discography, and magnetic resonance imaging. Procedures performed included Yeung Endoscopy Spine System （YESS） （n=25）, METRx MicroDiscectomy System （n=13）, and X-tube （n=14）. Patients were followed up for a mean of 13.5 months. Clinical outcomes were assessed using a visual analog scale （VAS） and Nakai criteria. Results All 3 procedures significantly improved radiating leg symptoms （P 〈0.005）. After surgery, 84.0%, 84.6%, and 92.8% of patients in the YESS, METRx, and X-tube groups had excellent or good outcomes. There were no statistically significant differences of VAS scores between the groups. The YESS procedure was associated with the shortest operation time, simplest anesthesia, and least trauma compared with the other 2 procedures, especially for type I herniations. The METRx procedure was the most suitable for type Ⅱ herniations and posterior endoscopic facetectomy. Posterior lumbar interbody fusion and unilateral pedicle screw instrumentation with X-tube was the most suitable for herniations combined with degenerative lumbar instability （type Ⅲ）. Conclusion Minimally invasive strategies and options should be determined with reference to the type of FLLDH.

Anatomical study of endoscope-assisted far lateral keyhole approach to the ventral craniocervical region with neuronavigational guidance

Background Image-guided neurosurgery, endoscopic-assisted neurosurgery and the keyhole approach are three important parts of minimally invasive neurosurgery and have played a significant role in treating skull base lesions. This study aimed to investigate the potential usefulness of coupling of the endoscope with the far lateral keyhole approach and image guidance at the ventral craniocervical junction in a cadaver model. Methods We simulated far lateral keyhole approach bilaterally in five cadaveric head specimens （10 cranial hemispheres）. Computed tomography-based image guidance was used for intraoperative navigation and for quantitative measurements. Skull base structures were observed using both an operating microscope and a rigid endoscope. The jugular tubercle and one-third of the occipital condyle were then drilled, and all specimens were observed under the microscope again. We measured and compared the exposure of the petroclivus area provided by the endoscope and by the operating microscope. Statistical analysis was performed by analysis of variance followed by the Student-Newman-Keuls test. Results With endoscope assistance and image guidance, it was possible to observe the deep ventral craniocervical junction structures through three nerve gaps （among facial-acoustical nerves and the lower cranial nerves） and structures normally obstructed by the jugular tubercle and occipital condyle in the far lateral keyhole approach. The surgical area exposed in the petroclival region was significantly improved using the 0° endoscope （1147.80 mm2） compared with the operating microscope （（756.28±50.73） mm2）. The far lateral retrocondylar keyhole approach, using both 0° and 30° endoscopes, provided an exposure area （（1147.80±159.57） mm2 and （1409.94±155.18） mm2, respectively） greater than that of the far lateral transcondylar transtubercular keyhole approach （（1066.26±165.06） mm2） （P 〈0.05）. Conclusions With the aid of the endoscope and image guidance, it is possible to approach the ventral craniocervical junction with the far lateral keyhole approach. The use of an angled-lens endoscope can significantly improve the exposure of the petroclival region without drilling the jugular tubercle and occipital condyle.

Classification and microsurgical treatment of foramen magnum meningioma

Background To investigate the classification and microsurgical treatment of foramen magnum meningioma(FMM).Methods We retrospectively analyzed 76 patients with FMM and classified them into two classifications,classification ABS according to the relationship between the FMM and the brainstem and classification SIM according to the relationship between the FMM and the vertebral artery(VA).All patients underwent either the far lateral approach(54 cases)or the suboccipital midline approach(22 cases).Results Of the 76 cases,47 cases were located ahead of the brainstem(A),16 cases at the back of the brainstem(B),and 13 cases were located laterally to the brainstem(S).There were 15 cases located superior to the VA(S),49 cases were inferior(I),and 12 cases were mixed type(M).Among 76 cases,71 cases were resected with Simpson grade 2(93.42%),3 with Simpson grade 3(3.95%),and 2 with Simpson grade 4(2.63%).We summarized four anatomical triangles:triangles SOT,VOT,JVV,and TVV.The mean postoperative Karnofsky performance score was improved in all patients(p<0.05).However,several complications occurred,including hoarseness and CSF leak.Conclusion ABS and SIM classifications are objective indices for choosing the surgical approach and predicting the difficulty of FMMs,and it is of great importance to master the content,position relationship with the tumor,and variable anatomical structures in the four"triangles"for the success of the operation.