Clarence H.S. Leung

Clinical Significance of Heterotopic Ossification in Cervical Disc Replacement: A Prospective Multicenter Clinical Trial

OBJECTIVE:Heterotopic ossification (HO) is a well-known complication in joint replacements, but its occurrence and clinical effect on cervical artificial discs has not yet been studied. The purpose of this study was to investigate the incidence of HO in cervical disc replacement, to identify any associated risk factors for HO, and to examine the relationship of HO with clinical outcomes. METHODS:The patient data for this observational study were obtained from the original Bryan Disc Study by the European Consortium. Occurrence of HO was defined by the McAfee classification on the cervical lateral x-rays at 12 months after surgery. Secondary outcome measurements included Odoms criteria and the Medical Outcomes Study Short-Form 36-Item Health Survey. RESULTS:Sixteen (17.8%) of the 90 studied patients experienced HO, and 6 (6.7%) of these patients experienced Grade 3 and 4 HO. Ten patients’ (11%) artificial discs were shown to have movement of less than 2 degrees on flexion and extension cervical x-ray at 12 months, with 4 of these patients having HO of Grade 3 or 4. Male sex (&khgr;2 = 4.1; P = 0.0407) and older patients (P = 0.023; odds ratio = 1.10; 95% confidence interval = 1.01–1.19) were associated with development of HO. CONCLUSION:There is a strong association of the occurrence of HO with subsequent loss of movement of the implanted cervical artificial disc. We have found that sex and age are two possible risk factors in the development of HO after cervical disc replacement.

Changes of cognitive functioning following mild traumatic brain injury over a 3-month period

Primary objective: To examine the cognitive functioning in patients with complicated mild traumatic brain injury immediately post-injury and at 1 and 3 months post-injury. Research design, methods, and procedures: Between-group comparisons were adopted for this study. Specifically, both patients and healthy controls were administered neuropsychological assessments measuring attention, memory and executive functions at three time points. Results: Findings indicate that patients performed significantly more poorly in information processing and divided attention, sustained attention, verbal recognition and verbal fluency immediately post-injury. While the information processing and divided attention of mild TBI patients improved at 1 month and returned to normal at 3 months post-injury, their sustained attention remained significantly poorer over the 3-month period. Conclusions: Findings suggest that attention dysfunction is noticeable immediately following a mild TBI. Different attention functions appear to recover at a different pace over time, suggesting that the condition may have a differential impact on the different sub-types of attention.

The comparative impact of video consultation on emergency neurosurgical referrals.

OBJECTIVE:Neurosurgical resources are concentrated in tertiary referral centers, whereas emergencies identified from district general hospitals are traditionally referred by telephone consultation (TC). Recent advances in communication technology offer the alternative options of teleradiology (TR) and video consultation (VC). This study aimed to determine the differences among these three consultation methods on the basis of their process-of-care indicators, clinical outcomes, and cost-effectiveness. METHODS:Patients with emergency neurosurgical conditions (head injury, stroke, and miscellaneous) from a district general hospital were randomized to three different modes of consultation: TC, TR, or VC. Process-of-care indicators (postresuscitation Glasgow Coma Scale score, consultation time required, diagnostic accuracy, and transfer decision and safety), 6-month clinical outcome, and cost-effectiveness of the three consultation modes were correlated. RESULTS:In a 3-year period, 710 patients were recruited and randomized to the three consultation modes (n = 235, 239, and 236, respectively). Demographic and clinical data were comparable. TR and VC showed a definite advantage in diagnostic accuracy over TC (89.1 and 87.7% versus 63.8%; P < 0.001). However, duration of the corresponding consultation process was longer for TR and VC than TC (1.01 and 1.3 h versus 0.70 h). A high failure rate (30%) was noted in VC. Thirty-three percent of patients were transferred to the neurosurgical center after consultation. The difference in consultation modes did not have an impact on transfer rate and safety. There was a trend toward more favorable outcome (61%; P = 0.12) and a reduced mortality (25%; P = 0.025) in TR compared with TC (54 and 34%, respectively) and VC (54 and 33%, respectively). The mean cost per patient in the VC group was slightly higher than the other two groups (TC versus TR versus VC = US

Cervical arthroplasty with the Bryan disc.

14,000 versus US

Spinal cord pilocytic astrocytoma with cranial meningeal metastases

14,400 versus US

The comparative impact of video-consultation on neurosurgical health services

16,300, respectively), but the differences were not statistically significant. CONCLUSION:Emergency neurosurgical consultation assisted by TR and VC achieved a higher diagnostic accuracy in comparison with conventional TC. Although VC did not show an advantage over TR in process-of-care indicators, clinical outcome, and cost, it has been proven to be a safe mode of consultation in emergency neurosurgery.

Validation of the modified radiosurgery-based arteriovenous malformation score in a linear accelerator radiosurgery experience in Hong Kong

CERVICAL ARTHROPLASTY IS a promising nonfusion alternative for the treatment of degenerative disc disease. After anterior cervical discectomy for neurological decompression, the intervertebral space is reconstructed by use of a metal and polymer prosthesis, allowing semiconstrained motion in multiple planes. This approach allows for preservation of cervical motion, potentially reducing the risk of transitional-level disease.

Spontaneous intracerebral haematoma with rapidly deteriorating level of consciousness: treatment by a mobile neurosurgeon.

Dissemination of tumour cells along the cerebrospinal fluid (CSF) pathway has been reported mostly in medulloblastomas, germ cell tumours or high grade gliomas. Juvenile pilocytic astrocytoma (JPA) is usually a benign astrocytoma. However, drop metastases of indolent nature from intracranial tumours to the spinal cord are documented. All of the previously reported cases represent metastases of cerebellar or hypothalamic tumours spreading to the spinal cord. We document in this paper the first report of a spinal cord pilocytic astrocytoma spreading via the CSF to the cerebral meninges. A 9 year old girl had a JPA of C5 to C7 subtotally resected. Two and a half years later she presented with hydrocephalus with radiologically meningeal enhancement. The meninges were biopsied which showed metastatic JPA. The girl was relatively well 4 years after initial surgery with residual tumour. Spinal cord JPA can rarely metastasize to the cranial meninges. Similar to intracranial tumours which spread to the spinal cord, such metastatic lesions are indolent.

Management of spinal injury

This study evaluated the impact of telemedicine technology on the provision of neurosurgical health services. We focused on the differences between the use of real time audio-visual teleconferencing and teleradiology versus conventional telephone consultations in the referral of neurosurgical patients from a large district general hospital. All patients requiring emergency neurosurgical consultation were included for randomization into telephone consultation only (Mode A), teleradiology and telephone consultation (Mode B) and video-consultation (Mode C). Measures of effectiveness included diagnostic accuracy and adverse events during the transfer and Glasgow Outcome Score. In a 10-month period, 327 patients were recruited and randomized into the study: the male/female ratio was 2:1 and the number of patients required to be transferred to the neurosurgical unit was 125 (38%). There was a trend towards a more favourable outcome in the video-consultation mode (44%, Mode C), versus teleradiology (31%, Mode B), versus telephone consultation (38%, Mode A). The interim data of this prospective randomized trial suggests that video-consultation may have a favourable impact on emergency neurosurgical consultations.

Neurosurgical emergencies in patients who are unfit for transfer: Is a mobile neurosurgeon a feasible option?

The modified radiosurgery-based arteriovenous malformation (AVM) score (modified AVM score or Pollock-Flickinger AVM score [PFAS]) is a simplified grading system developed to predict outcome after gamma knife radiosurgery for cerebral AVM. The purpose of this study was to test the PFAS in a cohort of patients managed with linear accelerator (LINAC) radiosurgery. We analyzed 70 consecutive patients with cerebral AVM treated with LINAC radiosurgery in Hong Kong. The scores were determined by the following equation: Modified AVM score=(0.1×volume [cm(3)])+(0.02×age [years])+(0.5×location). The location values are as follows: hemispheric/corpus callosum/cerebellar=0; basal ganglia/thalamus/brainstem=1. A total of 74% of patients presented with ruptured AVM before radiosurgery. The overall obliteration rate was 86%. Five (7%) patients developed new permanent neurological deficits from delayed bleeding or radiation-induced complications. Modified AVM score correlated with the percentage of patients with AVM obliteration without new neurological deficits (≤1, 96%; 1.01-1.50, 78%; 1.51-2.00, 90%; >2, 50%; Spearmans rho 0.354, p=0.003). In conclusion, the modified AVM score is a good predictor of patient outcome after LINAC radiosurgery in our cohort. The modified AVM score can be used to guide treatment selection for cerebral AVM and stratify patients for future comparative analyses.