Is It Real False Negative Finding in Motor Evoked Potential Monitoring during Corrective Surgery of Ankylosing Spondylitis? A Case Report.

We performed L1 posterior vertebral columnar resection and posterior correction for Andersson's lesion and thoracolumbar kyphosis in an ankylosing spondylitis patient during motor evoked potential (MEP) monitoring. We checked MEP intra-operatively, whenever a dangerous procedure for neural elements was performed, and no abnormal findings were seen during surgery. After the operation, we examined neurologic function in the recovery room; the patient showed a progressive neurologic deficit and no response to MEP. After emergency neural exploration and decompression surgery, the neurologic deficit was recovered. We questioned whether to acknowledge the results of this case as a false negative. We think the possible reason for this result may be delayed development of paralysis. So, we recommend that MEP monitoring should be performed not only after important operative steps but also after all steps, including skin suturing, for final confirmation.

Surgical treatment of "chin-on-pubis" deformity in a patient with ankylosing spondylitis: a case report of consecutive cervical, thoracic, and lumbar corrective osteotomies.

STUDY DESIGN: A case report. OBJECTIVE: To report the successful consecutive spinal osteotomies of multiple segments performed on a patient with extremely severe kyphotic deformity. SUMMARY OF BACKGROUND DATA: There have been no reports on the experience and surgical strategy of spinal osteotomy on multiple segments for severe global spine deformity. METHODS: A 48-year-old man, a patient with ankylosing spondylitis with "chin-on-pubis" deformity, underwent consecutive spinal osteotomies to correct the severe, fixed global kyphosis. The axial skeletons from the skull, all vertebrae, and both sacroiliac joints and hip joint were fused into a single bone. After both hip resectional arthroplasties for the first step, staged, sequential spinal osteotomies, including pedicle subtraction osteotomy (PSO) on C6, posterior vertebral column resection on T11-T12, and PSO on L3, were performed. Finally, both total hip arthoroplasties were performed. RESULTS: The chin-brow vertical angle improved from 140° to 15°. Correction angles of 45°, 70°, and 30° in the cervical, thoracic, and lumbar spines, respectively, were achieved without complication. At the last follow-up, excellent improvement in activities of daily living and horizontal gaze were achieved. CONCLUSION: This is the first report on C6 PSO and spinal osteotomies in whole spine segments. For patients with a severe global kyphotic deformity, it is important to place the patient in a stable prone position so that corrective surgery can be performed on the thoracolumbar spine. To accomplish this, initially correcting the deformities in the hip joints and the cervical spine can yield excellent clinical results.

Assessment of pedicle perforation by the cervical pedicle screw placement using plain radiographs: a comparison with computed tomography.

STUDY DESIGN: A retrospective study. OBJECTIVE: To suggest methods for detecting pedicle perforation on the basis of cervical pedicle screw (CPS) position on plain radiographs. SUMMARY OF BACKGROUND DATA: No studies have reported correlations between CPS position and pedicle perforation as observed on plain radiographs. This study was performed under the assumption that the detection of pedicle perforation would help to minimize the risks of neurovascular injury and help to obtain stable fixation. METHODS: A total of 48 subjects (with 205 screws) who had undergone CPS placement from C3 to C7 were enrolled in this study. To evaluate CPS position, the positions of the screw heads (neutral; the lateral margin of lateral mass cross the polyaxial screw head core, medial, or lateral) and tips (medial to uncovertebral joint [UVJ], within UVJ, or lateral to UVJ) on anteroposterior (AP) radiographs were analyzed. On the postoperative computed tomography, we analyzed the grade of pedicle perforation (grade 0: no PF; 1: < 25%; 2: 20%-50%; 3: > 50% of the screw diameter violation). Grades 0 and 1 were considered to be the correct position. RESULTS: Correct positioning was found for 174 screws (84.9%), and incorrect positioning was found for 31 screws (15.1%). The screw head was placed in a neutral position for 182 screws (88.8%), in the lateral position for 15 screws (7.3%), and in the medial position for 8 screws (3.9%). Of the 182 screws whose heads were in neutral position, 151 (83%) screws whose tips were located medial to the UVJ area were correctly positioned (sensitivity 0.89, specificity 1.0). A significant correlation was observed between the position of the screw tip and the grade of pedicle perforation (P = 0.000). CONCLUSION: A screw with a head that is located in a neutral position and a tip that is placed medial to the UVJ area on plain radiographs is considered to be in the safest position. A tip positioned lateral to the UVJ area or a head located out of the neutral position is expected to increase the risk of perforation. The use of intraoperative radiographs during CPS placement will help to identify the screws that are expected to cause pedicle perforation and allow the appropriate corrections to be made.

The influence of thoracic inlet alignment on the craniocervical sagittal balance in asymptomatic adults.

STUDY DESIGN: A prospective radiographic study. OBJECTIVES: To analyze the relationship between craniocervical sagittal balance and thoracic inlet (TI) alignment and to present the parameters that would help predict physiological lordosis of the cervical spine. SUMMARY OF BACKGROUND DATA: The physiological cervical lordosis (CL) and related factors has not been clearly defined yet. No studies have reported correlations between TI alignment and sagittal balance of the cervical spine. METHODS: Cervical spine lateral radiograph of 77 asymptomatic adult volunteers (aged between 21 and 50 y) were taken to analyze the following parameters. (1) Thoracic inlet parameters: thoracic inlet angle (TIA), T1 slope, neck tilting (NT); (2) cervical spine parameters: C0-2 angle, C2-7 angle, % ratio of (C0-2/C0-7 angle), (C2-7/C0-7 angle), and cervical tilting; (3) cranial parameters: C0 angle, cranial offset, and cranial tilting. Statistical analysis was performed using the Pearson correlation coefficients and multiple regression analysis. RESULTS: The mean TIA, T1 slope, NT were 69.5, 25.7, and 43.7, respectively. The mean C0-2 angle, C2-7 angle, C0 angle, cranial offset, cervical tilting, and cranial tilting were -22.4 degrees, -9.9 degrees, -9.3 degrees, 20.9 mm, 18 degrees, and 7.7 degrees, respectively. The ratio of C0-2:C2-7 angle was maintained as 77:23% and cervical tilting:cranial tilting was 70.2:29.8%. A significant correlation was found between TIA and T1 slope (r=0.694), T1 slope and C2-7 angle (r=-0.624), C2-7 angle and C0-2 angle (r=-0.547), C0-2 angle and cranial offset (r=-0.406). CONCLUSIONS: The thoracic inlet alignment had significant correlations with craniocervical sagittal balance. To preserve physiological NT around 44 degrees, large TIA increased T1 slope and CL and vice versa. TIA and T1 slope could be used as parameters to predict physiological alignment of the cervical spine. The results of this study may serve as baseline data for the evaluation of sagittal balance or planning of a fusion angle in the cervical spine.

Clinical outcomes of cervical radiculopathy following epidural steroid injection: a prospective study with follow-up for more than 2 years.

STUDY DESIGN: A prospective clinical outcome study. OBJECTIVE: To analyze clinical outcome and prognostic factors of the epidural steroid injection (ESI) for cervical radiculopathy (CR) patients who were considered surgical candidates. SUMMARY OF BACKGROUND DATA: The clinical outcomes and prognostic factors of ESI for CR have not been consistently reported, and there has been no prospective study with long-term follow-up. METHODS: ESI was administered in 98 patients (mean age = 50.1 yr, follow-up = 40.4 mo) with CR without major neurological deficit. A total of 3 or fewer ESIs were administered, using either the interlaminar or transforaminal technique. The patients were divided into 2 groups: those who did not have surgery and those who underwent surgery at the last follow-up. We analyzed statistical difference of relevant clinical (sex, age, duration of symptom, previous episode of CR, visual analogue scale [VAS] of arm pain, etc.), radiological factors (soft disc vs. hard disc, central disc vs. foraminal disc, single segment involvement vs. multiple segment involvement, degree of neural compression and degeneration, etc.) and clinical outcomes (VAS of arm pain, Odom's criteria, and neck disability index) between the 2 groups. RESULTS: The patients received mean 1.8 ESI treatments. At the final follow-up, 79 of the patients (80.6%) did not undergo surgery, whereas the other 19 patients (19.4%) underwent surgery. Of the clinical factors, recurred CR (15.2% vs. 42.1%, P = 0.022) and mean VAS score of arm pain before (6.1 vs. 8.2, P = 0.000) and after ESI (2.8 vs. 6.9, P = 0.000) were significantly different between both groups. Radiological factors and outcome parameters showed no significant difference. CONCLUSION: In more than 80% of patients with CR who were surgical candidates, surgery was avoided using ESI. The significant factors predisposing failure of ESI were intensity of symptom and a previous episode of CR. ESI is therefore considered a safe and effective treatment to choose before undergoing surgery.

Asymptomatic cervical cord compression in lumbar spinal stenosis patients: a whole spine magnetic resonance imaging study.

STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze incidence of asymptomatic cervical cord compression and related factors in lumbar stenosis patients. SUMMARY OF BACKGROUND DATA: Neural compression resulted from degenerative disc is not unusual in the asymptomatic cervical spine. However, its incidence and clinically related factors in lumbar stenosis patients have not been studied. METHODS: We analyzed lumbar stenosis index (LSI), cervical cord compression index (CCI), and Torg-Pavlov ratio of whole spine magnetic resonance images of 93 lumbar stenosis patients. We compared lumbar stenosis involving a single segment versus multiple segments in the cases with the LSI of double-level or more, patients in 60s versus in 70s, and male versus female for the above variables. RESULTS: Of total 93 cases, 71 cases did not demonstrate cervical cord compression, but moderate or severe cervical cord compression was observed in 22 cases (23.7%). The multiple segment lumbar stenosis group, the 70s group, and male group had statistically significant higher CCI. The correlation coefficient between the CCI and the LSI indicated a strong positive linear relationship with 0.54 (P = 0). CONCLUSION: Moderate or severe cervical cord compression was observed in 24% of lumbar stenosis patients. Asymptomatic cervical cord compression is more likely to be developed in lumbar stenosis patients who are aged, male, and involving multiple segments. These factors should be considered for management of lumbar stenosis patients.

Ventricular tachycardia during arthroscopic shoulder surgery: a report of two cases.

We routinely have performed arthroscopic shoulder surgery under general anesthesia in the beach chair position using epinephrine (0.33 mg/L) saline irrigation. At a 2-week interval, two patients, a 19-year-old man scheduled to undergo an arthroscopic Bankart repair for left traumatic anterior instability and a 49-year-old woman scheduled for an arthroscopic rotator cuff repair for a left rotator cuff tear, were resuscitated by chest compression and defibrillation due to a sudden developed cardiogenic shock following ventricular tachycardia at the time of arthroscopic shoulder surgery. They were transferred to the intensive care unit because their emergent echocardiogram showed significantly decreased cardiac functions. They were fully recovered and then discharged. Epinephrine was considered to be the cause of ventricular tachycardia because the two patients showed no anaphylactic reaction to drugs or symptoms of air embolism related to the beach chair position. In addition, according to our observation of epinephrine flow patterns, it was more likely that highly concentrated epinephrine was rapidly infused into the body. This complication is very rare. However, thorough understanding of the side effects and their development of epinephrine during arthroscopic shoulder surgery should neither be overemphasized nor disregarded.