T. A. D. Cadoux-Hudson

Amyloid in neurosurgical and neurological practice

The amyloidoses are a diverse group of diseases characterized by the deposition of specific proteins with distinct affinity to the dye Congo red, collectively called amyloid. The amyloidogenic proteins have acquired an abnormal, highly ordered, beta-pleated sheet configuration with a propensity to self-aggregate. The amyloid may be distributed in different organs with a remarkable diversity. Two broad categories of amyloidoses are recognised: The systemic (consisting of the primary or light chain form, the secondary or reactive form and the familial or hereditary form) and the localised that target specific organs. A tropism of amyloid proteins to the neural tissue produces certain patterns of central nervous system diseases: cerebral amyloid angiopathy, a substrate of spontaneous intracerebral haemorrhage; mature neuritic plaques found in Alzheimer disease and a subset of prion diseases; a topographically restricted accumulation of extracellular proteins giving rise to tumour-mimicking masses, the amyloidomas; and finally, spinal extradural amyloid collections that occasionally are found in the context of rheumatoid arthritis. In this review article we present original illustrative cases of amyloid diseases of the central nervous system that may be encountered in neurosurgical and neurological practice. Molecular aspects and clinical management problems are discussed.

Anterior cervical discectomy plus intervertebral polyetheretherketone cage fusion over three and four levels without plating is safe and effective long-term

Anterior cervical discectomy and fusion (ACDF) is an established treatment for single-level cervical spondylotic myelopathy and radiculopathy, yet its stand-alone use for multi-level disease of the subaxial cervical spine remains controversial. We report a prospectively studied case series of 30 patients receiving polyetheretherketone (PEEK) cage fusion over three and four cervical levels without anterior plating. Seven (23.3%) four-level procedures (all C3 to C7) were performed, the other 23 (76.7%) being three-level, with 19 (64.4%) at C4 to C7 and four (12.3%) at C3 to C6. Long-term follow-up of more than 2 years was available in 67% of patients. This cohort showed statistically significant improvements in visual analogue score for neck pain (p=0.0006), arm pain (p=0.0003) and Japanese Orthopaedic Association myelopathy score (p=0.002). Fused segment heights increased by 0.6-1.1%. Adjacent segment disease requiring ACDF at C3-4 was seen in 6.7% of patients (one after trauma) at a mean follow-up of 62 months. Same segment recurrence requiring posterior decompression with instrumented fusion was found in 10% of patients at a mean follow-up of 49 months, only one of whom had radiological evidence of cage subsidence. The results suggest the procedure is safe and effective with potentially less morbidity than anterior plating, shorter inpatient stays than posterior approaches, acceptable same segment recurrence and lower than predicted adjacent segment disease rates.

Craniocervical fusion for rheumatoid arthritis: comparison of sublaminar wires and the lateral mass screw craniocervical fusion.

The majority of rheumatoid ar thritis patients with C1/2 instability causing neck pain and neurological compromise can be treated with unisegmental fusion. However, a minority will require decompression and more extensive craniocervical fusion. Two cohorts of patients with rheumatoid arthritis requiring decompression and craniocervical fusion were included in a retrospective study comparing sublaminar wiring (Ransford Loop, n = 10, follow-up = 36 - 9.5 months) and lateral mass screws (Cervifix system, n = 11; follow-up = 39.7 - 7.9 months). Both cohorts of patients experienced significant improvements in high cervical pain scores [McGill 5-point score; preop = 4.5 - 0.75 for Cervifix and 4.5 - 0.75 for Ransford loop; postop = 1.17 - 0.9 ( p = 0.003) for Cervifix (at 39.7 months - 7.9) and 2.8 - 1.6 ( p = 0.011) for Ransford loop (at 36 - 9.5 months)]. Lateral mass screws for craniocervical fusion (seven out of 11 pain free) appear to produce better early results for rheumatoid arthritis patients suffering high cervical neck pain than sublaminar wire techniques (three out of 10 pain free).

Novel Approaches to Imaging Brain Tumors

Brain imaging techniques are assuming a greater range of roles in neuro-oncology. New techniques promise earlier recognition of the spread of tumors to the brain, which is useful in staging of disseminated disease, as well as better definition of small lesions associated with presentations of epilepsy. There is the promise that entirely noninvasive, specific diagnosis of brain tumors may become possible. Imaging methods are being used increasingly to direct and monitor therapy. Preoperative and intraoperative imaging are being used for guiding tumor surgery. An exciting potential goal for greater use of imaging is in the individualization of medical therapies either by analysis of in vitro responses or by visualization of drug responses on the tumor in situ. An important focus for technical development is in the robust integration of complementary information to allow optimization of the sensitivity and specificity of multimodal examinations.

Posterior occipitocervical instrumented fusion for dropped head syndrome after deep brain stimulation.

We describe dropped head syndrome in a patient with Parkinsons disease receiving subthalamic nucleus deep brain stimulation (DBS). Posterior occipitocervical instrumented fusion after transarticular screw fixation of an odontoid fracture is shown and its rationale explained. Pedunculopontine nucleus DBS as treatment for fall-predominant Parkinsons disease, and globus pallidus interna DBS for dystonia-predominant Parkinsons disease, are discussed.

La maladie de Grisel treated by combined C1-2 transarticular and C1 lateral mass screw fixation

The authors describe a novel posterior approach to atlantoaxial stabilization combining C1-2 transarticular and C1 lateral mass screws with vertical connecting rods to create a strong construct with four-point fixation. They present here a case of atlanto-axial instability secondary to infection, Grisels syndrome, necessitating instrumented stabilization after a period of close clinical and radiological observation following the initial cervical decompression and evacuation of retropharyngeal and epidural abscesses.

Acute foramen magnum syndrome from acquired Chiari I malformation relieved by ventriculoperitoneal shunt revision.

An adult case of shunt malfunction presenting with acute quadriparesis as a manifestation of foramen magnum syndrome with acquired Chiari type I malformation is described in this study. The corticospinal function was restored after shunt revision. MRI showing considerable ascent of cerebellar tonsils after surgery is shown. Theories regarding the formation of acquired Chiari I malformations, alongside the possible synergistic roles of intracranial pathologies and cerebrospinal fluid drainage in the development of this entity are discussed.

Optimising treatment strategies in spinal ependymoma based on 20years of experience at a single centre.

Spinal ependymomas are rare tumours, with total resection favoured where possible. Several case series assessing the outcome following neurosurgical treatment for spinal ependymoma advocate the usage of adjuvant radiotherapy in cases of subtotal resection, or in unencapsulated tumours. We assessed the outcome of 61 consecutive cases of spinal ependymoma in a single centre over a 20year period using a variety of outcome measures. Sex distribution was equal, with a mean age at surgery of 43.6years (range 5-76years). Overall, most tumours occurred in the lumbosacral region (70.5%), with fewer in the thoracic (27.9%) and cervical regions (18.0%). Myxopapillary features were seen in 41.0% of tumours, and were more common when occurring in the lumbar region (51.2%). Gross total resection was achieved in 52.5%, subtotal resection in 37.7% and biopsy alone in 9.8% of patients and 31.1% received adjuvant radiotherapy. Two-thirds of patients achieved an excellent post-operative neurological outcome (Frankel grade E). Tumour recurrence was rare. Gross total resection and good preoperative neurological condition were most strongly predictive of good outcome. Post-operative radiotherapy did not seem to confer survival benefit in this case series, even in cases of incomplete resection, leading us to question its utility for all cases of spinal cord ependymoma.

Double insurance redux

We commend Professor Goel for his innovative combination of C1-2 transarticular and C1 lateral mass screws. We discussed his and Harms’ intraarticular methods and Magerl’s transarticular approach in our technical report that described the novel application of his ‘double insurance’ fixation to la maladie de Grisel, but was editorially limited to three references. We have also performed it in 30 patients since 2004, of which 26 have at least 1 year of clinical follow-up with similarly good outcomes in the 18 patients he reported. Most had rheumatoid arthritis, others having trauma, os odontoideum and failed posterior instrumented craniocervical fusion. Ninety-two per cent had neck pain, 23% brachalgia and 11% limb weakness. Mean age at surgery was 59 years and mean inpatient stay 7 days. After 18 months’ mean follow-up, statistically significant (p5 0.05) improvements were observed in mean visual analogue scores both for neck pain from 5.5 to 1.6 and C2 pain from 2.1 to 0.5. Ranawat grading of functional disability showed median improvement from grade II to grade I. Three patients complained of persisting C2 hypoaesthesia as found in Goel’s patients. Two cases were converted to posterior instrumented craniocervical fusion. Like Goel, we find pre-operative CT invaluable to assess lateral mass and pedicle dimensions and ensure adequate C2 pedicle height. Unlike him, we use titanium polyaxial screws and rods rather than steel screws and plates; do not operate with the head in weighted traction nor do we advise 3 months of hard collar use after surgery as we consider the spine sufficiently stabilised intra-operatively. We agree with Prof. Goel that double insurance fixation is both safe and effective, particularly for treating atlanto-axial instability with basilar invagination in the rheumatoid spine in our experience, and furthermore after retropharyngeal abscess as our article illustrates.