Life threatening epistaxis complicating extended maxillotomy for chordoma

Postoperative hemorrhagic complications of the "open-door" maxillotomy approach to the skull base and clivus are uncommon. We report a case of maxillary artery pseudoaneurysm and discuss the management of this condition.

New proposals for training in neurosurgery

The rapidly evolving changes in working patterns, career structure and the regulation of training of doctors have provided an ideal opportunity for proposals to improve the programme for the training of neurosurgeons. The Education and Training Committee of the Society of British Neurological Surgeons (D.G. Hardy, A. J. W. Steers, N. T. Gurusinghe, P. M. Foy, P. van Hille, R. A. Cowie, H. A. Crockard, O. Sparrow and S. Burn) has, in recent months, worked closely with the Specialist Advisory Committee (SAC) in neurosurgery, Department of Health (Modernizing Medical Careers Group, H. A. Crockard, A. Havers, T. Hobbs) and colleagues from the major neuroscience specialties to develop a new programme based on a 'Common Stem' approach. This article describes the principles of the programme. The proposals have received approval by the Council of the SBNS, the Presidents of the four Surgical Royal Colleges and the Senate of Surgery.

Comparison of seven different scales used to quantify severity of cervical spondylotic myelopathy and post-operative improvement

Considerable uncertainty exists over the benefit that patients receive from surgical decompressive treatment for cervical spondylotic myelopathy (CSM). Such difficulties might be addressed by accurate quantification of CSM severity as part of a trial determining the outcome of surgery in different patient groups. This study compares the applicability of various existing quantitative severity scales to measurement of CSM severity and the effects on severity of surgical decompression. Scores on the following scales were determined on 100 patients with CSM preoperatively and then again six months following surgical decompression: Odom's Criteria, Nurick grade, Ranawat grade, Myelopathy Disability Index (MDI), Japanese Orthopaedic Association (JOA) Score, European Myelopathy Score (EMS) and Short Form-36 Health Survey (SF36). All the scales showed significant improvement following surgery. However, each had differing qualities of reliability, validity and responsiveness that made them more or less suitable. The MDI showed the greatest sensitivity between different severity levels, sensitivity to operative change and reliability. However, analysis of all the questionnaire scales into components that looked at different aspects of function revealed potential problems with redundancy and a lack of consistency. This prospective observational study provides a rational basis for determining the advantages and disadvantages of different existing scales in measurement of CSM severity and for making adaptations to develop a scale more specifically suited to a comprehensive surgical trial.

Paroxysmal raised intracranial pressure associated with spinal meningeal cysts

Raised intracranial pressure in association with spinal meningeal cysts has rarely been reported. We describe four patients in whom evidence of paroxysmal raised intracranial pressure was found in association with spinal meningeal cysts. Cerebrospinal fluid diversion procedures have previously been shown to relieve local symptoms due to spinal cysts. In our patients symptoms of paroxysmal headache were alleviated by this method, suggesting a causal relationship with the raised pressure. This association may be an under diagnosed cause of paroxysmal headaches. We review the medical literature on the classification of spinal meningeal cysts, evaluate the theories of their origin and offer suggestions on the pathogenesis of the abnormal CSF dynamics that may allow an interplay between raised intracranial pressure and spinal meningeal cysts to produce paroxysmal symptoms.

Two cases of quadriparesis following anterior cervical discectomy, with normal perioperative somatosensory evoked potentials

Two cases illustrate an uncommon failure of perioperative somatosensory evoked potential (SEP) monitoring to detect iatrogenic lesions causing temporary quadriparesis during straightforward cervical surgery. In both cases, anterior cervical discectomy at one or two levels was undertaken with bone graft and titanium implants, and cortical SEP were monitored to alternate stimulation of the left and right median or ulnar nerves. The SEP showed only minor changes during surgery, not considered pathologically significant, and were normal when recorded postoperatively. Both patients, however, experienced marked postoperative limb weakness or paralysis. Motor evoked potentials (MEP) recorded postoperatively to transcranial magnetic stimulation were absent. The clinical motor deficits resolved over the ensuing months. In spite of the normally low incidence of "false negatives," in these two cases SEP monitoring failed to detect a iatrogenic lesion causing moderate to severe, though temporary, motor impairment. Monitoring of MEP may be considered as an alternative to SEP during anterior cervical procedures, while combined monitoring of SEP and MEP may be the ideal.

The champagne angle

A patient's observation led us to investigate whether drinking from a champagne flute required more cranio-cervical extension than drinking from other types of wine glasses. We measured the cranio-cervical extension required by normal volunteers to drink from four different types of glass. The mean [95% confidence intervals] extension from the neutral position required to drain each glass was: narrow flute 40 degrees [35-44]; wide flute 22 degrees [19-25]; wine glass 26 degrees [24-29]; champagne saucer 0 degree [-1-2]. Drinking from the narrow rimmed champagne flute required significantly more extension than the other types of glass (p < 0.001), and 73% of the total available cranio-cervical extension.

A multidisciplinary team approach to skull base chordomas

OBJECT

A multidisciplinary team devised a protocol for long-term care of patients with skull base chordomas. In this study they describe their approach.

METHODS

Forty-two patients presented between 1986 and 1998 and were treated by maximum surgical cytoreduction and photon radiation therapy. Tumor volume-doubling time determined on the basis of magnetic resonance imaging, immunostaining, and cell proliferation (Ki67 labeling index [LI]) studies indicated growth rates of individual chordomas. The best outlook was associated with the greatest extent of tumor removal achieved during the first operation. There were no deaths associated with patients who underwent first-time surgery, but there was a 7.1% mortality rate associated with those who underwent subsequent operations. Cerebrospinal fluid leaks, additional cranial nerve palsies, and pharyngeal wound problems were the most difficult management problems encountered after second and subsequent surgeries. The time interval between operations was usually between 2 years and 3 years after the first surgery; very few patients required a second surgery, with a quiescent period in excess of 5 years. Life-table 5- and 10-year survival rates were 77% and 69%, respectively.

CONCLUSIONS

The authors believe that this series of skull base chordomas provides new insights into the management of these lesions, particularly with regard to techniques that increase survival times and studies that aid in formulating prognoses.

A multidisciplinary team approach to skull base chondrosarcomas

OBJECT

The authors review their experience with treating skull base chondrosarcomas, which are much rarer than skull base chordomas and differ from them in prognosis and treatment.

METHODS

Seventeen patients (12 male and five female patients) with histologically verified chondrosarcomas were followed up prospectively over a 12-year period. The mean age at presentation was 35.9 years. Most patients presented with cranial nerve palsies. Seven had undergone surgery prior to referral to the authors' unit. All underwent maximum surgical cytoreduction by the most direct surgical approach; only the two patients harboring the mesenchymal variant underwent radiotherapy.

CONCLUSIONS

One patient died of a pulmonary embolus; the patients harboring mesenchymal chondrosarcomas died at 20 and 36 months, respectively, after treatment. Of the remaining patients, 93% were alive 5 years postsurgery and had a projected 10-year survival rate of 84% (mean survival time 9.3 years). These data emphasize the very slow progression of this tumor compared with skull base chordoma.

Clinical and radiological correlates of severity and surgery-related outcome in cervical spondylosis

OBJECT

The aim of this study was to determine if radiological features could be used to predict outcome in patients with cervical spondylotic myelopathy (CSM).

METHODS

The authors studied 69 patients consecutively referred to The National Hospital, Queen Square, for decompressive surgery. Data obtained from preoperative cervical spine magnetic resonance (MR) imaging studies were each analyzed on two separate occasions by two blinded radiologists. The parameters determined were signal change and the presence and severity of compression. Clinical outcome was determined by pre- and postoperative timed walks, as well as by evaluation of myelopathy disability index scores, Ranawat classification, and Nurick grades. There was good inter- and intraobserver reliability for determination of radiological data. A significant relationship was found between MR imaging signal change and surgery-related outcome, as reflected by improvement in walking parameters; however, this was confounded by the fact that signal change also related to preoperative walking parameters, and those patients for whom preoperative walking function was worse experienced greater functional improvement in walking postoperatively. The relationships between ambulatory-related data and severity or extent of spinal cord compression were less marked.

CONCLUSIONS

Cervical cord compression and intrinsic MR imaging signal change correlate with clinical severity, and, in this population, the presence of signal change was correlated with better surgery-related outcome. However, confounding factors and the lack of strong correlation indicate that these radiological measurements are insufficient to be used as a reliable tool for predicting surgery-related benefits in individual patients.

Bilateral posterolateral approach to mirror-image C-2 neurofibromas. Report of four cases

Multiple nerve root tumors are usually present in patients afflicted with neurofibromatosis Type 1. Although rare, upper cervical mirror-image neurofibromas have been reported in the medical literature, and their surgical management has been addressed in several reports; however, little has been mentioned or is known regarding upper cervical or craniocervical stability following resection of these tumors. In this report the authors describe four cases of large mirror-image C-2 neurofibromas resected in two stages via the posterolateral approach. One patient presented with acute neurological deterioration after a biopsy sample had been obtained, whereas the other three presented with gradual onset of lower-extremity weakness over several months. The time interval between the first and second decompressive surgery ranged from 10 days to 12 weeks. There were no surgery-related complications, and all patients recovered motor function in their extremities. During a follow-up period of 16 to 36 months, there was no clinical or radiological evidence of upper cervical spine instability. Although the series is too small to draw any definitive conclusions, in the authors' experience the posterolateral approach provides a direct route for the successful surgical treatment of bilateral craniocervical nerve root tumors without destabilizing the upper cervical segments.

Skull base chordomas: correlation of tumour doubling time with age, mitosis and Ki67 proliferation index

The aim of the study was to assess the relationship between the rate of clinical tumour growth and various histological features, including Ki67 labelling index, in skull base chordoma. Cases of skull base chordoma from 19 patients (six female, 13 male; age range 8-63 years) were reviewed and the diagnosis confirmed based on histological and immunohistochemical features. In each biopsy cellularity, pleomorphism, mitotic activity, apoptotic bodies, necrosis and inflammatory cell infiltrate were graded and Ki67 labelling index (LI) calculated as a measure of proliferation. Tumour doubling time was assessed by quantitative analysis of tumour volumes in post-operative magnetic resonance images and correlated with age, sex, histological parameters and Ki67 LI. It was shown that increasing patient age, the presence of mitotic figures or a Ki67 LI in excess of 6% were associated with faster growing tumours.

Precise cannulation of the foramen ovale in trigeminal neuralgia complicating osteogenesis imperfecta with basilar invagination: technical case report

OBJECTIVE AND IMPORTANCE

Trigeminal neuralgia is a rare feature of basilar invagination, which is itself a complication of osteochondrodysplastic disorders. Microvascular decompression is an unattractive option in medically refractory cases. The conventional percutaneous approach to the trigeminal ganglion is anatomically impossible because the foramen ovale points inferiorly and posteromedially. We report a new technique for image-guided trigeminal injection in a patient with basilar invagination complicating osteogenesis imperfecta.

CLINICAL PRESENTATION

A 26-year-old woman with osteogenesis imperfecta presented with a 3-year history of typical left maxillary division trigeminal neuralgia, which was poorly controlled by carbamazepine at the maximum tolerated dose. She had obvious cranial deformities, left optic atrophy, delayed left eye closure, tongue atrophy, but normal facial sensation and corneal reflexes. A computed tomographic scan and magnetic resonance imaging confirmed severe basilar invagination.

TECHNIQUE

Frameless stereotactic glycerol injection of the left trigeminal ganglion was performed under general anesthesia using the infrared-based EasyGuide Neuro system (Philips Medical Systems, Best, The Netherlands) with magnetic resonance imaging and computed tomographic registration. The displaced and distorted left foramen ovale was cannulated via a true frameless stereotactic method with the trajectory determined by virtual pointer elongation. The needle placement was confirmed with injection of contrast medium into the trigeminal cistern. The path needed to enter the foramen traversed the right cheek, soft palate, and left tonsil. The patient went home pain-free with a preserved corneal reflex and no complications.

CONCLUSION

Frameless stereotaxy allows customization to individual patient anatomy and may be adapted to a variety of percutaneous procedures used in areas where the anatomy is complex.

Occipitocervical stabilization for myelopathy in patients with rheumatoid arthritis. Implications of not bone-grafting

BACKGROUND

Approximately 0.9 percent of the white adult population of the United States and 1.1 percent of the adult population in Europe are affected by seropositive rheumatoid arthritis. As many as 10 percent of those patients may need an operation for atlantoaxial subluxation. Severe instability, especially when associated with vertical subluxation of the odontoid process, can result in progressive cervical myelopathy. Typically, occipitocervical fixation has been performed for these patients with use of autograft bone to achieve long-term stability through a solid fusion. Harvesting the bone graft increases the operative risk to the patient and may result in increased morbidity. In our experience, patients who have had no clear radiographic evidence of fusion following use of occipitocervical instrumentation seemed to have done as well as those who have had obvious fusion. One assumption is that the clinical improvement might be attributable simply to stabilization of the joint rather than to osseous fusion. A longitudinal study was performed on patients with rheumatoid arthritis who required an operation because of craniocervical or upper cervical instability.

METHODS

The results of clinical, radiographic, functional, and self-evaluations were studied to determine the efficacy of treatment and to compare the outcomes of bone-grafting with those of procedures done without bone-grafting in a group of 150 patients who underwent posterior occipitocervical stabilization with use of a contoured metal implant (a Ransford loop) that was affixed by sublaminar wires. Internal fixation was performed in 120 patients without bone-grafting and in thirty patients with use of autogenous bone-grafting. Preoperatively, 23 percent (thirty-five) of the 150 patients had mild neurological involvement (class II, according to the system of Ranawat et al.), 45 percent (sixty-eight) had objective findings of weakness and long-tract signs but were able to walk (class III-A), and 29 percent (forty-three) were quadriparetic and unable to walk (class III-B). The age of the patients at the time of the operation ranged from twelve to eighty-three years (mean, sixty-two years).

RESULTS

There were significant improvements in postoperative Ranawat classes at all time-periods (range, p < 0.00005 to p = 0.0066) and in patient ratings of neck pain (range, p < 0.00005 to p = 0.0044) compared with preoperative scores. With the numbers available, there were no significant differences between the patients managed with a graft and those managed without grafting with respect to survival after the operation, Ranawat class, head or neck-pain rating, presence of subaxial abnormalities, radiographic craniovertebral motion, or vertical subluxation. Overall mortality at one month was 10 percent (fifteen of 150), although this value varied directly with the degree of preoperative disability. A second cervical spine operation was required in 11 percent (sixteen) of the 150 patients.

CONCLUSIONS

While patients who have rheumatoid disease with anterior atlantoaxial subluxation should be treated with posterior atlantoaxial arthrodesis with use of bone-grafting and internal fixation, we believe that those who present with vertical instability and multi-level involvement can be treated with posterior occipitocervical stabilization with use of a contoured occipitocervical loop and sublaminar wire fixation without bone-grafting. Furthermore, we believe that the use of preoperative traction, bone cement, or a postoperative halo vest is unnecessary. Avoiding the harvesting of autogenous bone for grafting reduced the morbidity of this operation without compromising the outcome in these already sick patients.

Management of tuberculomas of the craniovertebral junction

Tuberculosis of the craniovertebral junction is extremely rare. However, recent evidence suggests that the incidence of this condition may be increasing in the United Kingdom. The diagnosis is often difficult despite advances in imaging using MRI. CT guided biopsy of lesions often yields inconclusive results. The transoral approach to the anterior craniovertebral junction provides excellent access to this region with a low operative morbidity and mortality, enabling biopsy of lesions and decompression of the neuraxis. Management of secondary atlantoaxial instability, regarding both timing and method of stabilization, is controversial. We report two cases of tuberculomas of the craniovertebral junction, that illustrate the role of transoral surgery in both diagnosis and treatment of this condition. Previous management strategies are reviewed and future recommendations are presented.

Spinal intradural tumours: Part I--Extramedullary

Sixty-six patients had surgery for an intramedullary nerve sheath tumour under the care of one surgical team in a 16-year period. Surgery concentrated on radical intra- and extradural excision combined if necessary with vertebral column reconstruction. Ninety procedures were used in 35 males and 30 females with an age range 12-81 years. Forty-five per cent were located in the cervical, 26% in the thoracic and 29% in the lumbosacral region. Eighteen patients had NF1 and two patients NF2. Sixty-five per cent were schwannomas, 27% were mixed histology and 6% malignant. In terms of functional outcome, 37 patients improved by one or more Frankel grades, three deteriorated by one Frankel grade and no one who presented with symptoms alone deteriorated. There were no operative deaths; no instrumentation failures and five patients developed a CSF leak.

Spinal intradural tumours: Part II--Intramedullary

The results of surgical management in 54 patients with intramedullary spinal cord tumours are presented. Cervical tumours were most frequent (25/54) followed by thoracic (16/54) and then lumbar (14/54). Ependymomas and astrocytomas were the most common tumour types. Total tumour removal was possible in just over half of the cases. Surgical complications included: two deaths, six patients with CSF leaks and one with wound infection. Postoperatively three patients had worsening of their motor deficit (unable to walk) and three patients had worsening of urinary sphincter function. Conversely, three patients who were unable to walk preoperatively were able to walk postoperatively, whilst four patients with sphincter disturbance showed improvement. Total tumour removal was not associated with increased risk of postoperative neurological deficit. Long-term follow up (2-18 years) was possible in 40 patients; 90% were still independently mobile. Our results compare favourably with other European studies and data from the North American units which have pioneered this surgery.

Fracture of an ossified transverse ligament. Case report

✓ The authors report on the management of a patient in whom a fracture through an ossified transverse ligament had occurred, review the pertinent literature, and discuss the possible causes of ossification of the transverse ligament.

Quantitative assessment of cervical spondylotic myelopathy by a simple walking test

BACKGROUND

We developed a 30 m walking test as a quantifiable measure of severity of cervical spondylotic myelopathy (CSM), which will be of use in determining the effects of decompressive surgical treatment.

METHODS

Preoperative measurements were made in 41 patients with CSM of 30 m walking times, number of steps taken over this distance, myelopathy disability index (MDI), and Nurick scores. The walking factors were compared with a similar number of age-matched and sex-matched controls. The individuals in the study were patients with CSM and no other relevant pathology consecutively referred for decompressive surgery to the National Hospital for Neurology and Neurosurgery.

FINDINGS

Both walking time and the number of steps taken were significantly worse in pre-operative patients than in controls. The walking data were highly reproducible over three trials. Postoperatively, there was a significant improvement in walking time (p=0.0018) and number of steps taken (p=5.87 x 10(-6)). Only two of 41 patients were worse postoperatively. There was also a significant improvement in MDI (two-tailed Wilcoxon, related samples; p<0.0001) and Nurick scores (two-tailed Wilcoxon p<0.0001) postoperatively. The preoperative and postoperative walking scores were significantly and equally correlated with the MDI and Nurick scores.

INTERPRETATION

Timed walks are an easily performed, quantitative, and valid means of assessing CSM and the effects of surgery.

Peroperative determination of safe superior transarticular screw trajectory through the lateral mass

STUDY DESIGN

Computerized anatomic reconstruction of the dry axis vertebra was performed to determine radiologic guidelines for safe superior transarticular screw trajectory.

OBJECTIVES

To reconstruct the transarticular screw trajectory, using computer-aided design techniques, and develop a technique that provides real-time intraoperative guidance during screw placement.

SUMMARY OF BACKGROUND DATA

A recent osteometric study of 50 dry specimens of the axis noted significant vertebral artery groove anomalies in 22% of specimens. There are presently no anatomic or radiologic guidelines to help surgeons avoid an enlarged vertebral groove, despite the fact that a safe screw trajectory through the lateral mass is primarily dependent on the its depth and the internal height of the lateral mass.

METHODS

Using computer-aided design techniques, we re-analyzed the vertebral grooves of 50 dry specimens and mapped minimum and corrected safe superior trajectories for any given depth of this groove. This knowledge was extrapolated to spiral computed tomographic scan data, which was used to develop the clinical method for safe superior trajectory. Real-time fluoroscopy was used to apply the method intraoperatively.

RESULTS

Internal height less than 2.1 mm or values less than 0.85 for the ratio of the mean internal height over the mean vertebral groove depth would result in unacceptable risk to vertebral artery injury and improper screw purchase. With every 0.5-mm increase in groove depth, the angle of trajectory increases by 1 degree at a pedicle length of 30 mm. There is an inverse linear relation between the superior angle of trajectory and the pedicle length (2 degrees = 5 +/- 0.5 mm). Screw diameter-dependent trajectory correction is required (3.5 mm = 7 degrees).

CONCLUSIONS

Before atlantoaxial transarticular surgery, vertebral groove depth should be evaluated and a safe screw trajectory angle should be plotted to determine anatomic suitability. This trajectory angle can be used with intraoperative real-time fluoroscopy to guide the surgeon during screw insertion.

Transmaxillary anterior decompressions in patients with severe basilar impression

Severe basilar impression leads to an upward translocation of the upper cervical spine and clivus into the foramen magnum and is a diagnosis best made with computed tomography or magnetic resonance imaging scans. Basilar impression may be a primary condition or secondary to bone softening disorders. Symptoms relating to direct neuraxial compression, obstruction to cerebral spinal fluid outflow, and vascular compromise all have been described. Management depends on the exact nature of the abnormality seen, but it is now firmly accepted that those with anterior neuraxial compression should have an anterior decompression. The severe basilar impression and craniofacial abnormalities seen in osteogenesis imperfecta together with the progressive nature of the condition have led to the development of a specific surgical response, the open door maxillotomy combined with a contoured loop fixation of the cervical spine. Little is known of the long term outcome of severe basilar impression, and long term studies undertaken by centers familiar with the condition and its management are required if definitive care is to be delivered to these patients.

Magnetic resonance imaging-compatible posterior cervical implant for occipitocervical stabilization. Technical note

Posterior cervical stabilization was accomplished in 30 patients (19 females and 11 males) by using sublaminar titanium cables and a new titanium bullet-shaped implant. Seventeen patients underwent occipitocervical fixation and 13 others were treated subaxially. These patients have been followed for 18 to 52 months (mean 36 months), and no implant has failed during the follow-up period.

A neurosurgically reversible cause of respiratory dysfunction in rheumatoid arthritis

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The Glasgow Coma Score: reliable evidence?

The Glasgow Coma Score (GCS) is an important factor in the management and prognosis of a patient with neurosurgical pathology. We have found that there is often a disparity between the quoted and actual GCS of patients referred to this unit. We performed a prospective observational study to determine the proportion of patients referred with a correct GCS. Forty-two (51%) out of a total of 82 patients had a correct GCS on referral. The proportion of patients referred with a correct GCS did not vary with either the grade or speciality of the referring doctor.

Cartilaginous development of the human craniovertebral junction as visualised by a new three-dimensional computer reconstruction technique

Serial transverse histological sections of the human craniovertebral junction (CVJ) of 4 normal human embryos (aged 45 to 58 d) and of a fetus (77 d) were used to create 3-dimensional computer models of the CVJ. The main components modelled included the chondrified basioccipital, atlas and axis, notochord, the vertebrobasilar complex and the spinal cord. Chondrification of the component parts of CVJ had already begun at 45 d (Stage 18). The odontoid process appeared to develop from a short eminence of the axis forming a third occipital condyle with the caudal end of the basioccipital. The cartilaginous anterior arch of C1 appeared at 50-53 d (Stages 20-21). Neural arches of C1 and C2 showed gradual closure, but there was still a wide posterior spina bifida in the oldest reconstructed specimen (77 d fetus). The position of the notochord was constant throughout. The normal course of the vertebral arteries was already established and the chondrified vertebral foramina showed progressive closure. The findings confirm that the odontoid process is not derived solely from the centrum of C1 and that there is a 'natural basilar invagination' of C2 during normal embryonic development. On the basis of the observed shape and developmental pattern of structures of the cartilaginous human CVJ, we suggest that certain pathologies are likely to originate during the chondrification phase of development.

Back pain during pregnancy and after childbirth: an unusual cause not to miss

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Intradural neurotropic spread of malignant mesothelioma. Case report and review of the literature

This 54-year-old man with a history of right-sided malignant mesothelioma presented with signs of a partial spinal cord syndrome. The tumor had invaded the lower trunk of the brachial plexus and spread along the T-1 nerve root beneath the arachnoid onto the spinal cord itself. Mesothelioma, despite its known predilection for local spread, is rarely encountered within the spinal canal. Neurotropism is commonly encountered in facial malignancies; however, it has never been reported to affect the brachial plexus and spinal cord.

Vertical translocation. Part II. Outcomes after surgical treatment of rheumatoid cervical myelopathy

This is a prospective observational study in 116 patients with rheumatoid arthritis and vertical translocation who underwent cervical spine surgery after developing symptomatic myelopathy. These patients, whose mean age was 62 years, had suffered from rheumatoid arthritis for almost 25 years. Surgery was performed via a combination of anterior (67 transoral decompressions) and posterior approaches. Surgical morbidity was recorded in 39% of patients, with a 30-day mortality rate of 10.3%, which was largely related to poor preoperative neurological grade. Neurological improvement of at least one Ranawat class was observed in 55 patients. Univariate analysis revealed the following clinical variables to be associated with a good neurological outcome (Ranawat class): younger age and good preoperative muscle power. Significant radiological variables included the degree of vertical translocation as measured by the Redlund-Johnell method and the preoperative spinal cord area. The degree of transgression in the foramen magnum did not significantly affect neurological outcome. Neither the anterior nor the posterior atlantodens interval predicted neurological recovery. Multiple logistic regression models were constructed based on the preliminary evidence of the authors' univariate analysis and these confirmed the importance of preoperative neurological function, spinal cord area, and the degree of vertical translocation in influencing the final neurological grade.

Is the technique of posterior transarticular screw fixation suitable for rheumatoid atlanto-axial subluxation?

The rheumatoid patient with atlanto-axial subluxation presents a major challenge to the spinal surgeon, owing to the poor wound healing and bone quality. Traditional wiring techniques are associated with a high complication and failure rate. Posterior transarticular screw fixation of the atlanto-axial joint offers a credible alternative and when combined with a Gallie construct offers immediate true 3-point stability. It is, however, a difficult and demanding technique which carries a risk of vertebral artery, cranial nerve and spinal cord damage. The question that arises therefore is "Do the improved stability rates afforded by this technique really justify the risks of arterial and neurological damage?" To date there have been no studies of this technique dealing solely with the rheumatoid patient, with most reports dealing with a heterogeneous patient population, mainly trauma-related cases. The purpose of this report is to analyse critically our results with particular reference to the complications that we have encountered and the technical reasons for their occurrence. We analysed the clinical and radiological data of 38 rheumatoid patients (six males: 32 females, mean age of 54 years) with atlanto-axial subluxation who underwent transarticular screw fixation. Our analysis centred on screw malposition and complications. Parametric and non parametric statistical analysis was performed. Significance was accepted at the 5% level (p < 0.05). Our analysis revealed that three vertebral arteries were damaged. Two of these were recognized at the time of surgery, with the remaining case only suspected following postoperative CT to assess screw positioning. Vertebral artery occlusion was subsequently confirmed by angiography. All three patients were asymptomatic from their arterial injury. There was only one neurological complication in this series, and this was caused by a high screw, which damaged the hypoglossal nerve with a temporary nerve palsy ensuing. Four screws broke, all were made of titanium, but more importantly, all were also associated with contralateral screw malposition. Stability was achieved in 95% of cases overall. The high stability rates afforded by this technique do appear to justify the inherent risks of this procedure. If unilateral screw fixation only is achieved, we would recommend a period of halo immobilization until osseous union occurs.

Ossified pseudomeningocoele following laminectomy: case reports and review of the literature

To date, four cases of ossified extradural pseudocyst have been described, the first being in 1951 by Verbiest who described unusual forms of compression of the cauda equina including a case of a lumbo-sacral extradural cyst and a case of 'knotting' of a caudal nerve root. We present an additional two cases.

Vertical translocation: the enigma of the disappearing atlantodens interval in patients with myelopathy and rheumatoid arthritis. Part I. Clinical, radiological, and neuropathological features

This statistical comparison between patients with cervical myelopathy secondary to horizontal atlantoaxial subluxation and those with vertical translocation is designed to elucidate the mechanisms responsible for cranial settling and the effect of translocation on the development of spinal cord compression. In a 10-year study of a cohort of 256 patients, 186 suffered from myelopathy and 116 (62%) of these exhibited vertical translocation according to the Redlund-Johnell criteria. Vertical translocation occurred after a significantly longer period of disease than atlantoaxial subluxation (p < 0.001). Translocation was characterized clinically by a high cervical myelopathy with features of a cruciate paralysis present in 35% of individuals compared with 26% who exhibited horizontal atlantoaxial subluxation (p = 0.29), but there was a surprising paucity of cranial nerve problems. The patients with vertical translocation had a greater degree of neurological disability (p = 0.002) and poorer survival rates (p = 0.04). Radiologically, vertical translocation was secondary to lateral mass collapse and associated with a progressive decrease in the atlantodens interval ([ADI], r = 0.4; p < 0.001) and pannus (p = 0.003). Thirty percent of patients exhibited an ADI of less than 5 mm. This phenomenon has been termed pseudostabilization. The authors' studies emphasize that the ADI (frequently featured in the literature) is totally unreliable as an indicator of neuraxial compromise in the presence of vertical translocation.

Cerebello-pontine angle epithelioid haemangioendothelioma in a 4-year-old boy

A 4-year-old boy presented with a cerebello-pontine angle tumour thought to be an invasive acoustic schwannoma. Subtotal resection of the tumour was performed and followed by radiotherapy; histologically the lesion was an epithelioid haemangioendothelioma.

Metastatic carcinoma of the temporal bone presenting as glomus jugulare and glomus tympanicum tumours: a description of two cases

Two cases of metastatic carcinoma of the temporal bone, that simulated glomus tumours on thorough preoperative evaluation are described. Although rare, metastatic spread to this area is recognized, but presentation in this way is unique.

The one bone spine: a failure of notochord/sclerotome signalling?

Three cases of extensive vertebral fusions with absent clivo-axial angle are presented. The 'bone-within-bone' appearance in two patients with almost complete fusion of the spine suggested ossification of the notochord and perinotochordal sheath. On the basis of the radiological appearances and the results of recent molecular genetic studies on vertebrate embryos, the suggested time of segmentation failure along the axis of the craniovertebral junction and between vertebrae is the third to fifth week of gestation. The possible roles of the Pax-1 gene and of signalling between notochord and sclerotome are discussed, concluding that an early defect of the notochord may be responsible for this type of failure of segmentation. Indications for surgery in these cases included cord compression with brachialgia and 'chin-on-chest' deformity causing severely restricted visual fields. A critical review of clinical lessons learned in the operative treatment is presented.

VARIATION OF THE GROOVE IN THE AXIS VERTEBRA FOR THE VERTEBRAL ARTERY

Transarticular screws at the C1 to C2 level of the cervical spine provide rigid fixation, but there is a danger of injury to a vertebral artery. The risk is related to the technical skill of the surgeon and to variations in local anatomy.

We studied the grooves for the vertebral artery in 50 dry specimens of the second cervical vertebra (C2). They were often asymmetrical, and in 11 specimens one of the grooves was deep enough to reduce the internal height of the lateral mass at the point of fixation to ≤2.1 mm, and the width of the pedicle on the inferior surface of C2 to ≤2 mm. In such specimens, the placement of a transarticular screw would put the vertebral artery at extreme risk, and there is not enough bone to allow adequate fixation.

Before any decision is made concerning the type of fixation to be used at C2 we recommend that a thin CT section be made at the appropriate angle to show both the depth and any asymmetry of the grooves for the vertebral artery.

Variation of the groove in the axis vertebra for the vertebral artery. Implications for instrumentation

Transarticular screws at the C1 to C2 level of the cervical spine provide rigid fixation, but there is a danger of injury to a vertebral artery. The risk is related to the technical skill of the surgeon and to variations in local anatomy. We studied the grooves for the vertebral artery in 50 dry specimens of the second cervical vertebra (C2). They were often asymmetrical, and in 11 specimens one of the grooves was deep enough to reduce the internal height of the lateral mass at the point of fixation to < or =2.1 mm, and the width of the pedicle on the inferior surface of C2 to < or =2 mm. In such specimens, the placement of a transarticular screw would put the vertebral artery at extreme risk, and there is not enough bone to allow adequate fixation. Before any decision is made concerning the type of fixation to be used at C2 we recommend that a thin CT section be made at the appropriate angle to show both the depth and any asymmetry of the grooves for the vertebral artery.

Inadequate PAX-1 gene expression as a cause of agenesis of the thoracolumbar spine with failure of segmentation. Case report

An unusual case with absence and "fusion" of several thoracic and lumbar vertebral bodies leading to a severe thoracolumbar kyphos is presented. Late-onset neurological deterioration occurred due to spinal cord compression, which was treated with anterior decompression. Although several mechanisms for the development of these extensive and rare abnormalities have been proposed, the cause in humans remains unknown. An embryological basis is presented in the light of recent advances in molecular genetics, which show that abnormal notochordal signals and Pax-1 gene expression can produce an experimental phenotype very similar to the one in the patient described here. Thus it is suggested that faults in these early developmental processes may be, at least in part, responsible for the development of such extensive anomalies.

Radiological and anatomical evaluation of the atlantoaxial transarticular screw fixation technique

Sixty-one patients treated with C1-2 transarticular screw fixation for spinal instability participated in a detailed clinical and radiological study to determine outcome and clarify potential hazards. The most common condition was rheumatoid arthritis (37 patients) followed by traumatic instability (15 patients). Twenty-one of these patients (one-third) underwent either surgical revision for a previously failed posterior fusion technique or a combined anteroposterior procedure. Eleven patients underwent transoral odontoidectomy and excision of the arch of C-1 prior to posterior surgery. No patient died, but there were five vertebral artery (VA) injuries and one temporary cranial nerve palsy. Screw malposition (14% of placements) was comparable to another large series reported by Grob, et al. There were five broken screws, and all were associated with incorrect placement. Anatomical measurements were made on 25 axis bones. In 20% the VA groove on one side was large enough to reduce the width of the C-2 pedicle, thus preventing the safe passage of a 3.5-mm diameter screw. In addition to the obvious dangers in patients with damaged or deficient atlantoaxial lateral mass, the following risk factors were identified in this series: 1) incomplete reduction prior to screw placement, accounting for two-thirds of screw complications and all five VA injuries; 2) previous transoral surgery with removal of the anterior tubercle or the arch of the atlas, thus obliterating an important fluoroscopic landmark; and 3) failure to appreciate the size of the VA in the axis pedicle and lateral mass. A low trajectory with screw placement below the atlas tubercle was found in patients with VA laceration. The technique that was associated with an 87% fusion rate requires detailed computerized tomography scanning prior to surgery, very careful attention to local anatomy, and nearly complete atlantoaxial reduction during surgery.

Quadriplegia with cervical cord compression

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Failure of osseous conduction with cervical interbody BOP graft

We report three patients treated for cervical radiculopathy by anterior cervical discectomy and BOP grafting. Because of recurrent symptoms re-exploration was carried out 30 months later in the first case, 10 months in second and 8 months in the third case. At reoperation the grafts were disrupted into easily separable fibres. Histologically, there were no osteoblast or fibroblast cells or new bone formation. We suggest that contrary to the manufacturer's claims, the material acts only as a "spacer" and does not conduct bone formation.

Use of an adjustable, transportable, radiolucent spinal immobilization device in the comprehensive management of cervical spine instability. Technical note

In this report the authors describe a device that consists of a transportable, radiolucent board that couples to a standard halo head ring. The board provides continuous cervical spine immobilization during all phases of acute medical treatment of cervical spine instability, including closed reduction, transport, radiographic imaging, and operative procedures. By combining the advantages of several existing systems, this immobilization device facilitates and improves the safety of comprehensive acute management of cervical spinal instability by eliminating the need for patient transfer from stretcher to radiography machine to operating table. Its radiolucent construction and its compatibility with standard operating tables allow unencumbered surgical access and ample room for biplanar fluoroscopy, thereby also facilitating operative procedures, particularly the placement of internal spinal fixation.

Split cervical spinal cord with Klippel-Feil syndrome: seven cases

We report seven cases of rare high cervical split spinal cord associated with extensive vertebral fusions (Klippel-Feil anomaly). In light of previous embryological theories and recent research findings we attempt to explain the origin of split cord and vertebral fusions. Two distinctly separate mechanisms are suggested for the development of split cords observed in our cases: a midline lesion bisecting the neuroepithelium and the notochordal plate could be responsible for complete splitting of the cervical cord with anterior bony defect while a localized disturbance of cervical neural tube closure would account for cases with partial dorsal splitting of the cord with posterior vertebral defect. Vertebral fusion anomalies are likely to be associated with disturbance of Pax-1 gene expression in the developing vertebral column. We confirm with our cases the frequent association of failure of normal segmentation and split cord in the cervical region. Clinically, only three patients had neurological deficit which was mild and has remained stable, and they had no radiological evidence of tethering; the minimal disproportionate growth of the cord and spine and the rarity of a bony spur in the cervical region are the likely reasons. A conservative policy was therefore pursued in these cases with careful long-term follow-up.

Development of a functional scoring system for rheumatoid arthritis patients with cervical myelopathy

OBJECTIVE

To be able to measure disability objectively in rheumatoid arthritis complicated by cervical myelopathy.

METHODS

The responses to the Stanford health assessment questionnaire disability index were recorded from 250 consecutive patients (group 1) referred to our unit for spinal surgery. Using principal components analysis the questionnaire was reduced from 20 questions to 10 questions. In the second part of the study, the results of the questionnaire for those patients undergoing surgery from the original group of 250 patients were analysed with respect to outcome.

RESULTS

The reduction in the number of questions results in no significant loss of information, reliability (internal consistency Cronbach's alpha = 0.968) or sensitivity. The new scale, the myelopathy disability index, measures only one dimension (Eigen value 6.97) and may be more finely tuned to the measurement of disability in these myelopathic patients. When administered to the 194 patients undergoing cervical spine (group 2) surgery the myelopathy disability index was an accurate predictor of neurological and functional outcome, as well as survival following surgery (P < 0.0001).

CONCLUSIONS

The myelopathy disability index provides a much needed objective and reliable means of assessing disability in patients with rheumatoid involvement of the cervical spine and also in predicting outcome following surgical intervention. It also provides information for both the patient and surgeon alike, on what to realistically expect from surgery. Its adoption should facilitate comparisons between different forms of surgical intervention.

Somatosensory evoked potential monitoring in cervical surgery: identification of pre- and intraoperative risk factors associated with neurological deterioration

Cortical and subcortical somatosensory evoked potentials (SSEPs) were noninvasively monitored in 191 surgical procedures involving the cervical spine. In nine patients in the poorest neurological condition, SSEPs could not be monitored. Lower limb SSEPs were often too degraded to be useful. Upper limb responses were reliably recorded in 182 procedures, with a sensitivity of 99% and a specificity of 27% in 10 patients who developed neurological signs postsurgery. The aim of monitoring was to detect changes in spinal cord function at a time when neurological deterioration could be prevented or reversed, and these studies alerted the authors to certain clinical and SSEP risk factors associated with deterioration. Clinical and operative risk factors were: 1) poor pre-operative neurological function (one-third of Ranawat Class IIIb patients deteriorated); 2) use of instrumentation (the risk doubled in preoperatively unimpaired patients); 3) upper cervical and clival surgery (the risk tripled); and 4) and multisegmental surgery (increased risk with each additional level). There were SSEP changes in 33 patients. Fifty percent of patients with a complete loss had neurological damage, unlike those who had incomplete loss or whose electrical changes had recovered by the end of surgery. In the authors' view these "false positives" may represent real physiological changes, the effects of which might have been minimized by an alteration in the surgeon's response as a result of the warning. Although these initial studies have made this surgical team more alert to potential problems, the role of intraoperative SSEP monitoring is still being debated.

Predictors of outcome in the quadriparetic nonambulatory myelopathic patient with rheumatoid arthritis: a prospective study of 55 surgically treated Ranawat class IIIb patients

The functional results of surgery in patients with myelopathic nonambulatory rheumatoid arthritis (Ranawat Class IIIb) are often disappointing, with high rates of postoperative morbidity and mortality. The authors therefore undertook a detailed investigation of a cohort of 55 Ranawat Class IIIb patients (11 men and 44 women) with a mean age of 64.7 years who were recruited prospectively over a 10-year period (1983-1993), to determine what factors may accurately predict a good surgical outcome. Only 14 patients (25.5%) were judged to have had a favorable outcome as determined by an improvement to Ranawat Class I or II or an improvement of at least 0.5 points in the Stanford Health Assessment Questionnaire disability index. The early postoperative mortality rate was high (12.7%) in this group and almost one-quarter of the patients were dead within 6 months. These poor results mirror those already published in the existing literature. Univariate analysis revealed that age (p = 0.02), degree of vertical translocation (p = 0.05), and, more importantly, spinal cord area (p = 0.006) were significant predictors of outcome. Multiple logistic regression analysis showed that spinal cord area (p = 0.026) was, in fact, the major determinant of outcome and, indeed, of long-term survival (p = 0.001). The mean spinal cord area of those patients not achieving a good outcome was 44 mm2. The atlantodens interval (ADI) was not shown to be a significant outcome determinant, which may be explained by the correlation between an increasing vertical translocation and a decreasing ADI (r = 0.4, p = 0.01). Furthermore, as the degree of vertical translocation increased, the space available for the cord was observed to decrease (p = 0.003) commensurate with a reduction in spinal cord area (p = 0.02). Together, these findings strongly argue for earlier surgical intervention, before the development of vertical translocation, permanent neurological damage, and spinal cord atrophy can occur.

Biocompatible osteoconductive polymer versus iliac graft. A prospective comparative study for the evaluation of fusion pattern after anterior cervical discectomy

STUDY DESIGN

One hundred fifteen patients having symptomatic cervical disc disease were recruited prospectively for this study. They were allocated randomly for either autologous iliac bone graft or biocompatible osteoconductive polymer implants. Both groups were compared clinically and radiologically.

OBJECTIVES

Complications, long-term clinical and radiologic outcome, and hospital stay were compared to determine if biocompatible osteoconductive polymer was an improvement on iliac bone graft in terms of reduced donor site pain and shortened hospital stay.

SUMMARY OF BACKGROUND DATA

Donor site morbidity is a significant problem in anterior cervical fusion. Hospital stay is another factor in the recent era of cost consciousness. Biocompatible osteoconductive polymer has been used in many centers as a biodegradable implant to circumvent these problems.

METHODS

Smith-Robinson technique was used in 74 patients, and Cloward technique was used in 41 patients. Sixty-five patients had biocompatible osteoconductive polymer implants, and 50 patients had iliac bone graft. Patients were followed-up routinely in the outpatient clinic where pain visual analogue scale and Odom's criteria were used for outcome evaluation. Plain radiography, computed tomography scan, and magnetic resonance imaging were used for radiologic evaluation.

RESULTS

The mean hospital stay was 4.8 days for those with iliac bone graft and 4.7 days for those with biocompatible osteoconductive polymer. Clinical outcome was identical in both groups. The incidence of partial graft protrusion and postoperative intersegmental kyphosis was statistically higher with iliac bone graft (P = 0.018 and P = 0.02, respectively). "Sclerosis" started to form around biocompatible osteoconductive polymer like a "halo" at 2 months. It increased with time, and sometimes was associated with new osteophyte formation; however, there was no biocompatible osteoconductive polymer incorporation or biodegradation

CONCLUSIONS

Biocompatible osteoconductive polymer acts as a good "spacer" that reduces graft collapse and intersegmental kyphosis. However, it did not show any radiologic evidence of biodegradation or incorporation during the follow-up period of 24 months.

Motor evoked potential monitoring during spinal surgery: responses of distal limb muscles to transcranial cortical stimulation with pulse trains

During spinal surgery, motor evoked potentials (MEPs) were recorded from distal upper and lower limb muscles following multipulse transcranial electrical stimulation of the cortex. Twenty-two patients, 9 of them myelopathic, were anaesthetised with propofol +/- nitrous oxide. Using trains of 3-6 pulses separated by 2 ms, consistent responses generally measuring more than 100 microV were obtained from every patient except one, and persisted with nitrous oxide concentrations as high as 74%. Responses could usually be elicited from 3 or more limbs simultaneously, although the location of the stimulating anode was sometimes critical. The lower limb responses of one patient disappeared transiently during excision of an intramedullary tumour; his leg weakness was increased for a few days after surgery. Three other patients experienced increased weakness or spasticity, two without concomitant MEP changes and one with no recordable responses. Although other methods may be preferable in some circumstances, we believe this represents an advance over previously reported non-invasive techniques for peroperative MEP monitoring, and may be particularly useful for monitoring patients with myelopathy in the thoracic region.