Amir Ahmadian

Analysis of lumbar plexopathies and nerve injury after lateral retroperitoneal transpsoas approach: diagnostic standardization

OBJECT The minimally invasive lateral transpsoas approach has become an increasingly popular means of fusion. The most frequent complication is related to lumbar plexus nerve injuries; these can be diagnosed based on distribution of neurological deficit following the motor and/or sensory nerve injury. However, the literature has failed to provide a clinically relevant description of these complications. With accurate clinical diagnosis, spine practitioners can provide more precise prognostic and management recommendations to include observation, nerve blocks, neurodestructive procedures, medications, or surgical repair strategies. The purpose of this study was to standardize the clinical findings of lumbar plexopathies and nerve injuries associated with minimally invasive lateral retroperitoneal transpsoas lumbar fusion. METHODS A thorough literature search of the MEDLINE database up to June 2012 was performed to identify studies that reported lumbar plexus and nerve injuries after the minimally invasive lateral retroperitoneal transpsoas approach. Included studies were assessed for described neurological deficits postoperatively. Studies that did attempt to describe nerve-related complications clinically were excluded. A clinically relevant assessment of lumbar plexus nerve injury was derived to standardize early diagnosis and outline prognostic implications. RESULTS A total of 18 studies were selected with a total of 2310 patients; 304 patients were reported to have possible plexus-related complications. The incidence of documented nerve and/or root injury and abdominal paresis ranged from 0% to 3.4% and 4.2%, respectively. Motor weakness ranged from 0.7% to 33.6%. Sensory complications ranged from 0% to 75%. A lack of consistency in the descriptions of the lumbar plexopathies and/or nerve injuries as well as a lack of diagnostic paradigms was noted across studies reviewed. Sensory dermal zones were established and a standardized approach was proposed. CONCLUSIONS There is underreporting of postoperative lumbar plexus nerve injury and a lack of standardization of clinical findings of neural complications related to the minimally invasive lateral retroperitoneal transpsoas approach. The authors provide a diagnostic paradigm that allows for an efficient and accurate classification of postoperative lumbar plexopathies and nerve injuries.

Management of sagittal balance in adult spinal deformity with minimally invasive anterolateral lumbar interbody fusion: a preliminary radiographic study

OBJECT Minimally invasive (MI) fusion and instrumentation techniques are playing a new role in the treatment of adult spinal deformity. The open pedicle subtraction osteotomy (PSO) and Smith-Petersen osteotomy (SPO) are proven segmental methods for improving regional lordosis and global sagittal parameters. Recently the MI anterior column release (ACR) was introduced as a segmental method for treating sagittal imbalance. There is a paucity of data in the literature evaluating the alternatives to PSO and SPO for sagittal balance correction. Thus, the authors conducted a preliminary retrospective radiographic review of prospectively collected data from 2009 to 2012 at a single institution. The objectives of this study were to: 1) investigate the radiographic effect of MI-ACR on spinopelvic parameters, 2) compare the radiographic effect of MI-ACR with PSO and SPO for treatment of adult spinal deformity, and 3) investigate the radiographic effect of percutaneous posterior spinal instrumentation on spinopelvic parameters when combined with MI transpsoas lateral interbody fusion (LIF) for adult spinal deformity. METHODS Patient demographics and radiographic data were collected for 36 patients (9 patients who underwent MI-ACR and 27 patients who did not undergo MI-ACR). Patients included in the study were those who had undergone at least a 2-level MI-LIF procedure; adequate preoperative and postoperative 36-inch radiographs of the scoliotic curvature; a separate second-stage procedure for the placement of posterior spinal instrumentation; and a diagnosis of degenerative scoliosis (coronal Cobb angle > 10° and/or sagittal vertebral axis > 5 cm). Statistical analysis was performed for normality and significance testing. RESULTS Percutaneous transpedicular spinal instrumentation did not significantly alter any of the spinopelvic parameters in either the ACR group or the non-ACR group. Lateral MI-LIF alone significantly improved coronal Cobb angle by 16°, and the fractional curve significantly improved in a subgroup treated with L5-S1 transforaminal lumbar interbody fusion. Fifteen ACRs were performed in 9 patients and resulted in significant coronal Cobb angle correction, lumbar lordosis correction of 16.5°, and sagittal vertebral axis correction of 4.8 cm per patient. Segmental analysis revealed a 12° gain in segmental lumbar lordosis and a 3.1-cm correction of the sagittal vertebral axis per ACR level treated. CONCLUSIONS The lateral MI-LIF with ACR has the ability to powerfully restore lumbar lordosis and correct sagittal imbalance. This segmental MI surgical technique boasts equivalence to SPO correction of these global radiographic parameters while simultaneously creating additional disc height and correcting coronal imbalance. Addition of posterior percutaneous instrumentation without in situ manipulation or overcorrection does not alter radiographic parameters when combined with the lateral MI-LIF.

Minimally invasive lateral retroperitoneal transpsoas interbody fusion for L4–5 spondylolisthesis: clinical outcomes

OBJECT In this study the authors report on the clinical outcomes, safety, and efficacy of lateral retroperitoneal transpsoas minimally invasive surgery-lumbar interbody fusion (MIS-LIF) at the L4-5 disc space in patients with spondylolisthesis. This approach has become an increasingly popular means of fusion. Its most frequent complication is lumbar plexus injury. Reported complication rates at the L4-5 disc space vary widely in the literature, bringing into question the safety of MIS-LIF for the L4-5 region, especially in patients with spondylolisthesis. METHODS The authors retrospectively reviewed prospectively acquired multicenter databases of patients with Grade I and II L4-5 spondylolisthesis who had undergone elective MIS-LIF between 2008 and 2011. Clinical follow-up had been scheduled for 1, 3, 6, 12, and 24 months postoperatively. Outcome measures included estimated blood loss, operative time, length of hospital stay, integrity of construct, complications, fusion rates, visual analog scale (VAS), Oswestry Disability Index (ODI), and 36-Item Short Form Health Survey (SF-36). RESULTS Eighty-four patients with L4-5 MIS-LIF were identified, 31 of whom met the study inclusion criteria: 26 adults with Grade I and 5 adults with Grade II L4-5 spondylolisthesis who had undergone elective MIS-LIF and subsequent posterior percutaneous pedicle screw fixation without surgical manipulation of the posterior elements (laminectomy, foraminotomy, facetectomy). The study cohort consisted of 9 males (29%) and 22 females (71%) with an average age of 61.5 years. The mean total blood loss was 94 ml (range 20-250 ml). The mean hospital stay and follow-up were 3.5 days and 18.2 months, respectively. The average score on the ODI improved from 50.4 preoperatively to 30.9 at the last follow-up (p < 0.0001). The SF-36 score improved from 38.1 preoperatively to 59.5 at the last follow-up (p < 0.0001). The VAS score improved from 69.9 preoperatively to 38.7 at the last follow-up (p < 0.0001). No motor weakness or permanent deficits were documented in any patient. Correction of deformity did not have any neurological complications. All patients had improvement in anterolisthesis. Residual postoperative listhesis across cases was noted in 4 patients (12.9%). Transient anterior thigh numbness (Sensory Dermal Zone III) was noted in 22.5% of patients. CONCLUSIONS With its established surgical corridors through the retroperitoneum and psoas muscle, the MIS-LIF combined with posterior percutaneous pedicle screw fixation/reduction is a safe, reproducible, and effective technique for patients with symptomatic degenerative spondylolisthesis at the L4-5 vertebral segment.

Long-term outcome of vagus nerve stimulation therapy after failed epilepsy surgery

OBJECTIVE Adequate control of intractable epilepsy continues to be a challenge. Little is known about the role of VNS therapy in intractable epilepsy in patients who failed to respond to surgical management. The objective of the present study is to determine the efficacy of vagus nerve stimulation therapy in patients with intractable epilepsy who have failed surgical and medical therapy. METHODS All the patients who had persistent seizures after cranial surgery who subsequently underwent vagus nerve stimulator (VNS) placement at our institution from 1998 to 2008 were included in the study. Thirty-seven consecutive patients were enrolled and followed for the outcome measures of seizure burden, anti-epileptic drug (AED) burden and quality of life (QoL). Minimum follow-up was 18 months. RESULTS Overall, 24 (64.9%), 9 (24.3%), 4 (10.8%) patients reported less than 30%, between 30% and 60% and greater than 60% reduction in seizure frequency after VNS placement, respectively at a mean of 5 years follow-up period. Post-VNS anti-epileptic requirement exhibited a decreasing trend. 17 patients (45.9%) report an improvement in QoL (better or much better). CONCLUSION VNS therapy in patients who have failed medical and surgical therapies only provides marginal improvement in seizure control but has greater likelihood to improve subjective QoL issues. In addition, VNS has the potential to reduce AED burden without adversely impacting seizure management. Given the low surgical risk of VNS placement, vagus nerve stimulation as a therapeutic modality should be individualized to achieve best clinical response and fewest side effects.

The anatomical relationship of the diaphragm to the thoracolumbar junction during the minimally invasive lateral extracoelomic (retropleural/retroperitoneal) approach

OBJECT The thoracolumbar junction (T11-L2) poses an anatomical dilemma, given the presence of the lower rib cage and the diaphragm when performing anterolateral approaches. To circumvent dealing with the diaphragm, a minimally invasive lateral extracoelomic approach has been used to approach the thoracolumbar junction by mobilizing the diaphragm anteriorly. No anatomical studies have described the attachments of the diaphragm and their surgical significance during the lateral approach to the thoracolumbar spine. The objective of this study is to describe the anatomical relationship of the diaphragm in reference to the minimally invasive lateral approach to the thoracolumbar spine and its surgical significance. METHODS Nine adult fresh-frozen cadaveric specimens were dissected and studied (18 sides). All specimens were placed in the lateral decubitus position, similar to the surgical technique, for the dissections. The relationship between the retroperitoneum, retropleural space, diaphragm, and thoracolumbar spine was analyzed in reference to the minimally invasive lateral approach. Special attention was given to the attachments of the diaphragm and their relationship to the ribs during the early stages of the approach. RESULTS All 18 sides were successfully dissected, analyzed, and photographed. The diaphragm is a musculotendinous sheet extending between the thoracic and abdominal cavities. Its attachments can be divided into 3 main categories: 1) sternal or anterior, 2) costal or lateral, and 3) lumbar or posterior. These attachments are described in detail, with specific reference to the lateral approach. When performing the minimally invasive lateral extracoelomic approach to the thoracolumbar spine, the lateral and posterior attachments must be identified and dissected to successfully mobilize the diaphragm anteriorly. CONCLUSIONS The diaphragm has multiple attachments that can be categorized as anterior, lateral, and posterior. In reference to the minimally invasive lateral extracoelomic approach to the thoracolumbar junction, the surgically significant attachments are primarily to the 12th rib and transverse process of L-1.

Stand-alone minimally invasive lateral lumbar interbody fusion: Multicenter clinical outcomes

Stand-alone minimally invasive lateral transpsoas interbody fusion (MIS-LIF), without posterior instrumentation, is feasible because the technique does not necessitate the disruption of the stabilizing elements. The objectives of this study are to evaluate the efficacy and clinical outcomes of patients who underwent stand-alone lateral interbody fusion. A multicenter chart review was conducted to identify patients who underwent stand-alone MIS-LIF between 2008 and 2012. Patients were classified by spinal pathology (degenerative disc disease [DDD], spondylolisthesis [SL] and adult degenerative scoliosis [ADS]). Routine clinical follow-up was scheduled at 3, 6, and12 months. Outcome measures included hospital length of stay, fusion rates, neurologic complications, integrity of construct and clinical outcome questionnaires (Visual Analog Scale [VAS] and Oswestry Disability Index [ODI]). A total of 59 patients met the inclusion criteria. The average age was 60 years (range 31-86 years). Spinal pathologies treated were DDD in 37 (63%), SL in four (7%) and ADS in 18 (30%) patients. Fusion rate was 93% of patients (95% of levels) at 12 months. Two patients required re-operation. Mean hospital stay and follow-up were 3.3days (range 1-10) and 14.6 months, respectively. The mean preoperative VAS and ODI were 69.1 and 51.8, respectively. VAS improved to 37.8 (p<0.0005). ODI improved to 31.8 (p<0.0005). Seventy percent of patients had grade 0 subsidence while 30% had grade I and grade II subsidence. Stand-alone MIS-LIF is viable option in a carefully selected patient population for both single and multilevel disease and shows significant improvement in health related quality of life.

Functional recovery of severe obturator and femoral nerve injuries after lateral retroperitoneal transpsoas surgery

The minimally invasive lateral retroperitoneal transpsoas approach is a popular fusion technique. However, potential complications include injury to the lumbar plexus nerves, bowel, and vasculature, the most common of which are injuries to the lumbar plexus. The femoral nerve is particularly vulnerable because of its size and location; injury to the femoral nerve has significant clinical implications because of its extensive sensory and motor innervation of the lower extremities. The authors present an interesting case of a 49-year-old male patient in whom femoral and obturator nerve functional recovery unexpectedly occurred 364 days after the nerves had been injured during lateral retroperitoneal transpsoas surgery. Chronological video and electrodiagnostic findings demonstrate evidence of recovery. Classification and mechanisms of nerve injury and nerve regeneration are discussed.

Occipitocervical fusion via occipital condylar fixation: a clinical case series.

Study Design: Retrospective review/case series. Objective: This study aims to present the clinical feasibility of condylar fixation in occipitocervical (OC) fusion. Here, we present the largest clinical series to date of patients who underwent OC fusion via cervicocondylar fixation using a polyaxial screw/rod construct. Summary of Background Data: The novel technique using the occipital condyles as the sole cranial fixation point has been described. Both cadaveric and biomechanical studies, in recent literature, have shown technical feasibility and surgical safety of condylar fixation. Methods: We retrospectively reviewed a prospectively acquired database of all patients treated with OC fusion via cervicocondylar fixation at our institution between 2007 and 2011. All patients were scheduled for follow-up postoperatively at weeks 2, 6, 12, 24, and annually thereafter. Outcome measures included estimated blood loss, operative time, complications, integrity of the construct, and fusion rates. Exclusion criteria included condylar fracture, previous cervical fusion, or vertebral artery injury. Enrolled patients subsequently underwent posterior OC fixation using occipital condyle, C1 lateral mass, and/or C2 pars interarticularis screw fixation. Subaxial cervical fixation consisted of lateral mass screw placement. Intraoperative fluoroscopy and hypoglossal monitoring were used. Results: We identified 12 consecutive patients who underwent OC fusion using the occipital condyle as the cranial fixation point using polyaxial screws. The mean operative time was 283 minutes (192–416). The mean total blood loss was 229 mL (100–400). Mean follow-up was 21.4 months (4–39). One patient suffered from a superficial wound infection. There were no neural or vascular complications. Radiographic evidence of OC fusion was noted for all patients with >6-month follow-up. Conclusions: OC fusion using occipital condylar screws is a feasible alternative to current occipital plate fixation. Condylar screw fixation can be performed safely with successful arthrodesis as a treatment for OC instability in patients.

Combined subgaleal/myocutaneous technique for temporalis muscle dissection.

Background The frontal branch of the facial nerve (FBFN) is the most susceptible neural structure to injury during frontotemporal craniotomies. The balance between adequate temporalis muscle mobilization and frontal branch protection with minimal anatomical alteration is the philosophy behind our approach to temporalis muscle dissection. Objective To describe a combined subgaleal/myocutaneous technique for dissection and mobilization of the temporalis muscle in anterolateral cranial approaches. Methods Interdisciplinary literature review of the anatomical course of the FBFN was performed. Retrospective analysis of anterolateral craniotomies performed at our institution in which the combined subgaleal/myocutaneous (CSGMC) technique was performed. Results A total of 71 cases of anterolateral craniotomies (excluding full variant orbitozygomatic) were performed with the successful application of a CSGMC technique (36 pterional, 31 orbitopterional, and 4 fronto-orbital). Partial frontalis weakness was transient in one case. Conclusion The CSGMC technique provides sufficient protection for the FBFN and allows for adequate mobilization for a variety of skull base exposures while minimally violating myofascial anatomy. This is the first reported technique that allows both adequate temporalis muscle mobilization with performance of the one-piece orbitofrontal and orbitopterional approaches, without disruption of the superficial/deep temporalis fascia and fat-pad complex.

Decompressive craniectomy with massive intractable intraoperative cerebral edema: utilization of silicone sheet for temporary scalp closure

The authors present a case of extreme brain herniation encountered during decompressive craniectomy in a 21-month-old boy who suffered a trauma event that necessitated temporary scalp closure in which a sterile silicone sheet was placed. Although the clinical situation is usually expected to lead to brain death or severe disability, the patients 3-year follow-up examination revealed a highly functional child with a good quality of life. The authors discuss the feasibility and advantages of temporary scalp expansion as a treatment option when extreme brain herniation is encountered during craniotomy.