November 2000: 13 year old girl with back pain and leg weakness.

A 13 year-old girl presented with back pain and recurrent falls of one year, with more recent loss of ambulation and bladder control. Examination showed spasticity and a sensory level bilaterally at T8. CT and MRI scans showed an epidural soft tissue mass with spinal cord compression and destruction of the pedicle, transverse process and other portions of a mid-thoracic vertebral body. Histologic examination of the gross total resection showed a pigmented villonodular synovitis (PVNS). PVNS is most common in the knee and only 26 cases have been reported in the spine. Although vertebral bodies are rarely involved, it is important to include PVNS in the differential diagnosis of spinal lesions because of its tendency to recur locally if not totally resected.

A new method of in-vivo microdialysis of the human brain.

In-vivo microdialysis has been used extensively to study the neurochemical mechanisms of ischemia, epilepsy and hypoglycemia. It is also being increasingly used to document the response of neurons to various medications. Most of the work to date has been done in small animals. In the last 2 years, the technique has been adapted for use in patients with subarachnoid hemorrhage, head trauma, Parkinson's disease, brain tumors and epilepsy. Two of the major limiting factors are the invasiveness of the technique and the resultant potential for CNS infection. We describe a simple, safe and reliable method to measure neurochemical changes in the human brain with in-vivo microdialysis. We were able to easily monitor for 4-6 h daily for up to 4 days in awake or comatose patients with subarachnoid hemorrhage or head trauma. Cerebral concentrations of glutamate, GABA, other amino acids and catecholamines were measured. This technique thus has a potential for on-line measurements of neurotoxins in patients with unstable neurological conditions.

Differing perspectives on outcome after subarachnoid hemorrhage: the patient, the relative, the neurosurgeon.

OBJECTIVE: To better understand patients' and relatives' views of outcome after surgery for subarachnoid hemorrhage (SAH), we evaluated neurobehavioral changes, psychological distress, and family burden of patients who had been considered by their neurosurgeon as having a "good recovery" or a "moderate disability," as rated on the Glasgow Outcome Scale. METHODS: A heterogeneous sample of 28 patients treated surgically for SAH from an aneurysm or an arteriovenous malformation and their relatives separately underwent a semistructured interview. They also completed a revised version of the Adjective Checklist to assess their perceptions of the patient's neurobehavioral changes and the Brief Symptom Inventory as a measure of their own psychological distress. Levels of family burden on the relatives were evaluated with a Likert strain scale and the Zarit Burden Interview. RESULTS: Approximately 19 months after surgery for SAH, the majority of the patients reported significant negative neurobehavioral changes and negative changes in employment, energy levels, tolerance to mild stressors, leisure activities, and social and sexual relationships. Patients and relatives both reported elevated levels of psychological distress, and the relatives reported elevated levels of family burden. Patients' and relatives' perceptions differed, with the relatives reporting more problems; both viewed the patient's outcome more negatively than did the operating neurosurgeon. CONCLUSION: Despite the neurosurgeon's classification of patients as having a "good recovery" or "moderate disability," the majority of patients surgically treated for SAH reported psychosocial and neurobehavioral changes that were disabling for them and burdensome to their family. Patients and relatives who are interviewed separately by an experienced clinician may provide differing perspectives on SAH outcome that are not necessarily good.

In-vivo microdialysis study of extracellular glutamate response to temperature variance in subarachnoid hemorrhage.

Neurochemical changes may precede the development of clinical signs in neurological disease. Early identification of such changes may offer an opportunity to avoid or treat complications. Under experimental conditions, extracellular levels of glutamate and other amino acids can be monitored by in-vivo microdialysis in cerebral ischemia, head trauma and epilepsy. Data on the release of glutamate under ischemic conditions in humans are limited. There is no published data on the effects of temperature variation or other manipulations on the extracellular glutamate levels in humans. We report for the first time, the effects of changes in temperature on the extracellular cerebral glutamate levels as measured by in-vivo microdialysis, the dialysate being collected before, during and after cooling in four patients with subarachnoid hemorrhage. Three of the patients had in-vivo microdialysis carried out postoperatively. One patient underwent microdialysis three days prior to the surgical clipping of the aneurysm. In all patients, mild head cooling resulted in a significant decrease in extracellular glutamate levels. The effect of cooling was most apparent when the extracellular glutamate concentrations were high. In two patients, the extracellular glutamate levels increased sharply with fever but returned to normal once the temperature normalized. In vivo microdialysis can be used to measure extracellular glutamate and other neurotransmitters with minimal discomfort in awake humans. This technique offers a unique opportunity to monitor the neurochemistry in critically ill patients and it may aid in developing therapeutic intervention strategies to minimize undesired chemical responses.

Career changes among Saskatchewan physicians.

OBJECTIVE: To determine how often Saskatchewan physicians changed career paths during medical training and practice. DESIGN: Population survey (mailed questionnaire). SETTING: Saskatchewan. PARTICIPANTS: All 1077 active members of the Saskatchewan Medical Association were sent a questionnaire; 493 (45.8%) responded. OUTCOME MEASURES: Long-term career goal or plan in next-to-last year of undergraduate medical school, probable choice of career if forced to choose at that time, and number of physicians who changed their field of training or practice at any time since graduation. RESULTS: In all, 57.8% (237/410) of the respondents were currently practising in a field different from that planned in their next-to-last year of medical school, 63.5% (275/436) were not practising in the field they would have chosen if forced to at that time, and 42.9% (211/492) had changed their field of training or practice at some time since graduation. Older physicians, those who graduated outside of Canada and specialists were the most likely to have changed career paths, family physicians, and those who graduated in Saskatchewan were the least likely to have changed. CONCLUSION: The current system of postgraduate training in Canada does not permit career changes of the sort made by most of the practising Saskatchewan physicians in the survey sample. The implications of this new system are as yet unknown but require careful monitoring.

Mechanical integrity of subchondral bone in osteochondral autografts and allografts.

OBJECTIVE: To assess the influence of osteochondral graft preservation techniques on post-transplant biomechanics of graft and host subchondral bone in the knee joint. DESIGN: An experimental animal model (sheep), specifically the weight-bearing articular surface of the medial femoral condyle of the knee joints. INTERVENTION: Each sheep received, in the ipsilateral knee, an allograft that was (a) frozen without dimethyl sulfoxide (DMSO), (b) snap-frozen in liquid nitrogen or (c) frozen with DMSO. The contralateral knee received an autograft that was (a) snap-frozen, (b) treated with DMSO or (c) left untreated (fresh). MAIN OUTCOME MEASURES: Mechanical and material properties of bone, including maximal compression stress, modulus of elasticity and bone cores (from the graft centre and surrounding host bone). RESULTS: No significant differences were found in the mechanical properties of the subchondral bone under the graft, but there were significant changes in surrounding bone. Bone surrounding the grafts that were snap-frozen or frozen without DMSO was significantly stronger than the normal control bone. However, bone surrounding fresh autografts and cryoprotected allografts was not significantly different from normal control bone. CONCLUSIONS; The changes in the mechanical behaviour of the host bone may be associated with graft cell viability. The great stiffness of the subchondral host bone may have consequences for long-term graft integrity and for the development of degenerative osteoarthritis.