Martin Wood

Promoting fusion in minimally invasive lumbar interbody stabilization with low-dose bone morphogenic protein-2—but what is the cost?

BACKGROUND Using bone morphogenic protein (BMP) to augment fusion in spine surgery is widespread and lends itself in particular to minimally invasive lumbar fusion, where the surface area for fusion is significantly less than the equivalent open procedure. PURPOSE Here we described the use of very low-dose BMP in promoting fusion in minimally invasive lumbar interbody fixation but also highlight some of the potential complications of BMP-2 use and techniques available to reduce or avoid them. STUDY DESIGN Prospective observational study of consecutive patients undergoing minimally invasive lumbar interbody fusion with percutaneous pedicle screws. PATIENT SAMPLE Thirty patients aged between 22 and 78 years (mean 53 years). OUTCOME MEASURES Thin-slice lumbar computed tomography scanning with multiplanar reconstruction at 6 and 12 months postoperative. METHODS Thirty-six spinal levels were instrumented in total, of which four underwent posterior lumbar interbody fusion and 32 underwent transforaminal lumbar interbody fusion. Bone graft harvested locally was placed in the disc space with low-dose BMP-2 (1.4 mg per level). RESULTS Thirty-three of 36 spinal levels showed complete fusion at a mean postoperative scan time of 7.1 months. Two levels demonstrated partial fusion at 6 months, which was complete at 12 months. There was one case of nonunion at 12 months, which also demonstrated vertebral body osteolysis. Despite very low-dose BMP-2, two cases of asymptomatic heterotopic ossification were observed, and there were two cases of perineural cyst formation, one of whom required revision of the interbody cage. CONCLUSIONS The use of BMP with autograft in the disc space during minimally invasive lumbar interbody fusion is associated with a high rate of early fusion. Even with very low-dose BMP used in this study, complications related to BMP usage were not avoided completely.

Safety and efficacy of intradural extramedullary spinal tumor removal using a minimally invasive approach.

BACKGROUND: Although minimally invasive surgery for intradural tumors offers the potential benefits of less postoperative pain, a quicker recovery, and the avoidance of long-term instability from multilevel laminectomy, there are concerns over whether one can safely and effectively remove intradural extramedullary tumors in a fashion comparable to open techniques and whether the advantages of minimally invasive surgery are clinically significant. OBJECTIVE: To review our early experience with minimally invasive techniques for intradural extramedullary tumors of the spine. METHODS: Thirteen intradural tumors (1 cervical, 6 thoracic, 6 lumbar) in 11 patients were operated on using a muscle-splitting, tube-assisted paramedian oblique approach with hemilaminectomy to access the spinal canal while preserving the spinous process and ligaments. Fluoroscopy and navigation were used to determine the surgical level in all thoracic and lumbar cases. RESULTS: Satisfactory tumor resection using standard microsurgical techniques was achieved in all but 1 case using a minimally invasive approach. Surgical time and intraoperative blood loss were favorable compared with our open technique cases. There was no postoperative morbidity with the minimally invasive approach, although in 2 patients with tumors in the mid- and upper thoracic spine, the surgical incision was inaccurately placed by 1 level. In 1 case, the approach was converted to open when the tumor could not be found, and postoperatively there was a cerebrospinal fluid leak with infection that required readmission. CONCLUSION: Intradural extramedullary tumors can be safely and effectively removed using minimally invasive techniques. The pros and cons of minimally invasive vs open surgery are discussed.

Improving accuracy and reducing radiation exposure in minimally invasive lumbar interbody fusion

OBJECT The authors assessed the accuracy of placement of lumbar transpedicular screws by using a computer-assisted, imaged-guided, minimally invasive technique with continuous electromyography (EMG) monitoring. METHODS This was a consecutive case series with prospective assessment of procedural accuracy. Forty-seven consecutive patients underwent minimally invasive lumbar interbody fusion and placement of pedicle screws (PSs). A computer-assisted image guidance system involving CT-based images was used to guide screw placement, while EMG continuously monitored the lumbar nerve roots at the operated levels with a 5-mA stimulus applied through the pedicle access needle. All patients underwent CT scanning to determine accuracy of PS placement. All episodes of adjusted screw trajectory based on positive EMG responses were recorded. Pedicle screw misplacement was defined as breach of the pedicle cortex by the screw of more than 2 mm. RESULTS Two hundred twelve PSs were inserted in 47 patients. The screw misplacement rate was 4.7%. One patient experienced new postoperative radiculopathy resulting from a sacral screw that was too long, with lumbosacral trunk impingement. The trajectory of the pedicle access needle was altered intraoperatively on 20 occasions (9.4% of the PSs) based on positive EMG responses, suggesting that nerve root impingement may have resulted from these screws had the EMG monitoring not been used. CONCLUSIONS The combination of computer-assisted navigation combined with continuous EMG monitoring during pedicle cannulation results in a low rate of PS misplacement, with avoidance of screw positions that might cause neural injury. Furthermore, this technique allows reduction of the radiation exposure for the surgical team without compromising the accuracy of screw placement.

A comparison of CT-based navigation techniques for minimally invasive lumbar pedicle screw placement.

Study Design A comparison of 2 surgical techniques. Objective To determine the relative accuracy of minimally invasive lumbar pedicle screw placement using 2 different CT-based image-guided techniques. Summary of Background Three-dimensional intraoperative fluoroscopy systems have recently become available that provide the ability to use CT-quality images for navigation during image-guided minimally invasive spinal surgery. However, the cost of this equipment may negate any potential benefit in navigational accuracy. We therefore assess the accuracy of pedicle screw placement using an intraoperative 3-dimensional fluoroscope for guidance compared with a technique using preoperative CT images merged to intraoperative 2-dimensional fluoroscopy. Methods Sixty-seven patients undergoing minimally invasive placement of lumbar pedicle screws (296 screws) using a navigated, image-guided technique were studied and the accuracy of pedicle screw placement assessed. Electromyography (EMG) monitoring of lumbar nerve roots was used in all. Group 1: 24 patients in whom a preoperative CT scan was merged with intraoperative 2-dimensional fluoroscopy images on the image-guidance system. Group 2: 43 patients using intraoperative 3-dimensional fluoroscopy images as the source for the image guidance system. The frequencies of pedicle breach and EMG warnings (indicating potentially unsafe screw placement) in each group were recorded. Results The rate of pedicle screw misplacement was 6.4% in group 1vs 1.6% in group 2 (P=0.03). There were no cases of neurologic injury from suboptimal placement of screws. Additionally, the incidence of EMG warnings was significantly lower in group 2 (3.7% vs. 10% (P=0.03). Conclusions The use of an intraoperative 3-dimensional fluoroscopy system with an image-guidance system results in greater accuracy of pedicle screw placement than the use of preoperative CT scans, although potentially dangerous placement of pedicle screws can be prevented by the use of EMG monitoring of lumbar nerve roots.

Minimally invasive lumbar decompression: long-term outcome, morbidity, and the learning curve from the first 50 cases.

Study Design Prospective observational study. Objective To describe our experience with the first 50 cases of minimally invasive lumbar canal decompression in terms of patient outcome up to 2 years, the learning curve incurred, and complications when compared with our most recent 50 cases. Summary of Background Data Lumbar canal stenosis is a common condition in the elderly population, the symptoms of which respond well to surgical decompression. A minimally invasive approach offers potential short and long-term benefits to patients but the technique is associated with a learning curve and equivalence to open surgery regarding efficacy and complications needs to be demonstrated. Methods Fifty patients (mean age 70 y) who presented with clinical and radiological features of lumbar canal stenosis and who had failed a period of conservative management underwent lumbar canal decompression through a paramedian oblique, muscle splitting approach using a 16 to 18 mm operating tube and microscope. Outcome was assessed using the Oswestry Disability Index and Short Form-36 at 3 months, 1 year, and 2 years. Results Significant clinical improvements were seen at 3 months that were sustained at 1 and 2 years. Clinical outcome improved whereas operative time and complications fell as experience increased, helping to define the learning curve with this technique. Conclusions Minimally invasive lumbar decompression seems to offer patients a clinical benefit comparable to that observed in published open series, with potential advantages in terms of postoperative pain and recovery. However, there is a learning curve and whether this technique offers long-term benefits with regard to a reduction in back pain or postoperative spondylolisthesis is not yet known.

Epidemiological aspects of spontaneous subarachnoid haemorrhage in Queensland, Australia.

AIMS To examine the epidemiology of spontaneous subarachnoid haemorrhage (SAH) within the population of Queensland, Australia in 2002. METHODS A retrospective population and hospital-based survey of all cases of spontaneous SAH occurring within the population of Queensland (3.7 million) during the calendar year 2002 was performed. Cases were identified from hospital separation coding data and the register of births, deaths and marriages. Standard demographic data was recorded for each case identified. RESULTS The annual incidence of SAH in our population was 9.4 cases per 100,000. There was a steady increase in the incidence of SAH with increasing age, with the incidence rising to 38.8 per 100,000 in those aged greater than 80. The overall mortality rate was 33.1%, with 6% of all cases dying before reaching hospital care. The annual incidence in the indigenous population of Queensland was 8.9 /100,000.

Outcomes after surgery and postoperative radiotherapy for perineural spread of head and neck cutaneous squamous cell carcinoma

Queensland, Australia, has the highest rates of cutaneous squamous cell carcinoma (SCC). Perineural invasion (PNI) is associated with reduced local control and survival.

Minimally invasive transforaminal lumbar interbody fusion and spondylolisthesis.

The purpose of this study was to assess the clinical and radiological outcomes of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) surgery for lumbar spondylolisthesis. A prospective analysis was conducted of 23 consecutive patients with grade I or grade II lumbar spondylolisthesis who underwent a MI-TLIF using image guidance between August 2008 and September 2010. The patient group comprised 13 males and 10 females (mean age 57 years), 22 of whom underwent single level fusion and one patient with a two level fusion. All patients underwent postoperative CT scans to assess pedicle screw and cage placement and fusion at six months. The Oswestry Disability Index (ODI) scores were recorded preoperatively and at the six-month follow-up. We found that 22 of 23 (95.7%) patients showed evidence of fusion at six months with a mean improvement of 26.7 on ODI scores. The mean length of hospital stay was four days. The mean operative time was 172 minutes. Anatomical reduction of the spondylolisthesis was complete in 16 patients and incomplete in seven. Regarding complications, we observed: one of 94 (1.1%) pedicle screws misplaced, which did not require revision postoperatively; one of 23 patients (4.3%) with a pulmonary embolism and one of 23 (4.3%) patients with transient nerve root pain. There were no occurrences of infection and no postoperative cerebrospinal fluid leaks. We conclude that MI-TLIF offers patients a safe and effective surgical option for lumbar spondylolisthesis treatment. Furthermore, it may offer patients additional advantages in terms of postoperative pain and recovery.

Complications from minimally invasive lumbar interbody fusion: Experience from 100 patients

Minimally invasive lumbar fusion is well described and is reported to offer significant advantages to patients in terms of blood loss, a reduction in post-operative pain and a quicker recovery. However, this technique may expose patients to a greater risk of complications when compared to open lumbar instrumented fusion that may negate these advantages. Between January 2007 and March 2001, we conducted a prospective observational study of 100 consecutive patients (48 males and 52 females, mean age of 54 years) to investigate complications occurring from minimally invasive lumbar interbody fusion surgery using an image-guided technique. All patients underwent post-operative CT scans to assess implant placement. Scanning was repeated at 6 months to assess bony fusion. We observed the following complications: 2.5% (11/435) pedicle screw misplacement, 1.7% (2/120) interbody cage misplacement; 0.8% (1/120) interbody cage migration; 0.8% (1/120) patients requiring a post-operative blood transfusion; 2% (2/100) venous thrombo-embolism and 3% (3/100) patients with complications thought to be related to the use of bone morphogenic protein. There were no occurrences of infection and no cerebrospinal fluid leaks. We concluded that the rate of complications from minimally invasive lumbar interbody fusion is low, and compares favourably with the rates of complication from open procedures. Moreover, computerised navigation systems can be used in place of real-time fluoroscopy to guide implant placement, without an increase in the rate of complications.

Great auricular nerve perineural spread of squamous cell carcinoma.

Cutaneous squamous cell carcinoma is the second commonest skin cancer accounting for around 20% of malignant skin cancers. The highest incidence is in Queensland, Australia. Perineural infiltration occurs in 2.4% of cutaneous squamous cell carcinoma and when it occurs the prognosis is worse. Large nerve perineural infiltration (or perineural spread) which is noticeable either through neural symptoms, radiographically or histologically in resected specimens, has a completely different prognosis although the exact relationship is uncertain. The facial and trigeminal nerves are affected most commonly. We present two cases of great auricular nerve perineural spread and discuss the world literature and treatment options. Both of our cases remain free of recurrence at the time of publication. A 41-year-old male presented in July 2009 for further management of a recently excised metastatic submental lymph node and complained of a 3-month history of altered sensation over the left cheek and left earlobe. Clinical examination revealed only a thickened ‘cord-like’ area over his upper left sternocleidomastoid muscle below his left ear. The lymph node had been excised elsewhere and revealed metastatic squamous cell carcinoma with extracapsular spread. In 2008, he had a wide resection and vermillionectomy for a squamous cell carcinoma of the lower lip followed by a second excision for positive margins. He had also, over the years, received cryotherapy for a left cheek lesion without histological sampling. An ultrasound-guided fine needle aspiration was performed, revealing squamous cell carcinoma along the great auricular nerve. A magnetic resonance imaging (Figs 1,2) revealed a tubular enhancing structure running superficial and parallel to the left sternocleidomastoid which performed a u-loop behind the sternocleidomastoid inferiorly at the level of the C4/5 disc and then towards the cervical plexus. The structure terminated 1.5 cm lateral to the C3/4 exit foramen on the left side. Superiorly, the structure divided at the level of the parotid gland and could not be followed proximally. A left modified radical neck dissection and right level 1–4 neck dissection and superficial parotidectomy were performed. The great auricular nerve was multiply assessed along its course proximally and distally with frozen section and branches into the superficial parotid fascia were dissected carefully from the subdermal tissue. Frozen sections demonstrated positive margins proximally in C3 as far as C3 could be followed into the pre-vertebral muscles. Clear margins were obtained proximally in C2. Perineural spread of C3 into the spinal foramen was unexpected. We were also aware of a false positive frozen section at the proximal end of C3 and submitting the patient to unnecessary risk. We therefore marked the distal end of the C3 nerve, woke the patient and awaited the formal paraffin sections. A week later, a neurosurgical team performed a C2/3 foramenotomy with resection of left C3 nerve. Histology demonstrated clear margins at the proximal end of C3. The patient received post-operative radiotherapy to the course of the great auricular nerve to the spinal foramen and remains free of disease at 2 years. A further 57-year-old man was treated for a recurrent cutaneous squamous cell carcinoma of his right cheek which had spread to the superficial aspect of great auricular nerve. He again was treated with surgery in similar fashion to the first case with post-operative radiotherapy. He remains tumour free at 3 years following his original recurrence. In small nerve perineural infiltration, 32% of patients die from disease when nerves 0.1 mm or larger are involved. Overall, once clinical or radiological evidence of perineural spread is detected, then the 5-year survival is 20–30%. The exact pathogenesis of perineural spread is unknown, but the most accepted theory is that nerves provide a pathway of least resistance for growth of tumours. Perineural spread can present with pain, complete numbness or other dysaesthesias such as formication (sensation of ants crawling on the skin).