Rodney J. Laing

Middle cerebral artery occlusion without craniectomy in rats. Which method works best

Background and Purpose Our purpose was to assess the effectiveness of middle cerebral artery occlusion in producing acute focal ischemia in the rat by the use of Koizumis and Longas methods, in which occlusion is achieved by passing a nylon thread into the internal carotid artery. Methods Cerebral blood flow was measured by using the hydrogen clearance method, and the brains were examined histologically to assess ischemic damage. Results By Koizumis method profound reduction in cerebral blood flow was achieved in 28 of 30 rats (93%). The mean cerebral blood flow in the middle cerebral artery territory was 10.7 (95% confidence interval, 9.9–11.5) ml/100 g per minute. By Longas method reduction in cerebral blood flow was achieved in only 29 of 52 rats (56%), and in these animals mean cerebral blood flow was 33 (95% confidence interval, 28.3–33.7) ml/100 g per minute (p < 0.001 compared with Koizumis method). Cerebral blood flow was reduced to <16 ml/100 g per minute in only seven animals (24%). Conclusions By Koizumis method the depth of ischemia is more profound, occlusion is achieved in a much higher proportion of cases, and the incidence of perforation of the intracranial internal carotid is much less frequent than by Longas method.

The Sheffield Model of Subarachnoid Hemorrhage in Rats

BACKGROUND AND PURPOSE There is no comprehensive and reliable model available in small animals that is suitable for the study of subarachnoid hemorrhage (SAH). Most of the existing models either require extensive surgery to achieve SAH or neglect the importance of an injury to the vessel and the impact of suddenly raised intracranial pressure (ICP). The presented model is designed to overcome these shortcomings. METHODS Forty-three male Wistar rats were anesthetized. Regional cerebral blood flow was measured using the H2 clearance method bilaterally in the middle cerebral artery territory. ICP and blood pressure were continuously monitored. Blood gases were kept within physiological limits. SAH was produced by passing a nylon thread up through the right internal carotid artery and piercing a hole in the right anterior cerebral artery. The animals were divided into three experimental groups treated with varied operative techniques. After 3 hours the surviving animals were killed, and SAH was confirmed by postmortem examination. RESULTS The described method proved to be a reliable way of producing SAH in rats. The onset of SAH was characterized by a sudden increase in ICP. There were some differences in the reduction of regional cerebral blood flow and the survival rate in the experimental groups. This may represent differing degrees of severity of the produced SAH. CONCLUSIONS We present an inexpensive and reliable model of SAH in the rat that allows the early course of biochemical, physiological, and pathological changes to be studied.

Laminectomy for lumbar canal stenosis: a safe and effective treatment.

Lumbar canal stenosis (LCS) is a common condition affecting elderly patients for which a significant number undergo surgery. The validity and safety of simple laminectomy in this condition is not fully understood. Furthermore, the presence of pre-existing spondylolisthesis is controversial with respect to the need for additional spinal stabilization. We prospectively studied a consecutive cohort of 100 patients with clinical and radiological LCS under the care of a single spinal surgeon. Outcome measures (SF-36, visual analogue scores for back and leg symptoms, and the Roland/Morris back pain scores) were assessed preoperatively, 3 months postsurgery and at long-term (median 2 years) follow-up. We have shown a significant improvement in outcome sustained in the long-term with minimal morbidity. Patients with pre-existing spondylolisthesis accounted for 23% of the cohort and, having received identical treatment, showed no significant difference in outcome compared with patients with normal alignment.

The surgical management of metastatic spinal disease: prospective assessment and long-term follow-up

The last decade has witnessed a resurgence of interest in the surgical treatment of metastatic spinal disease to compliment radiotherapy. A recent randomized controlled trial looking directly at this issue concluded strongly in favour of a combination of surgical decompression and radiotherapy, and there is now growing enthusiasm for surgery to play a role in the management of these patients. We present a prospective cohort study of 62 patients who presented with metastatic cord or cauda equina compression, and were treated with surgical decompression and fixation where necessary. Patients were treated by one surgeon working in a single unit. They were followed-up long term and were assessed objectively, by clinical assessment and prospective questionnaires that included SF36, visual analogue pain scores and Roland Morris back pain scores. Sixty-two patients with a median age of 62 (22 – 79 years, 27 male) were included in the study. The commonest primary tumours were breast (26%) and lymphoma (13%). The majority of patients had involvement of thoracic vertebrae (58%). 56% of patients were alive at 1 year and 28% at 3 years, with significant improvements observed in both walking and continence. Similarly, significant improvements were seen in SF36 quality of life scores as well as pain. With careful patient selection, long-term survival and good quality of life can be achieved. However, not every patient is suitable or appropriate for surgery, and the discussion focuses on where the surgical threshold should be set.

Pre- and postoperative motor conduction times, measured using magnetic stimulation, in patients with cervical spondylosis

Motor conduction time (MCT) between head and neck in pathways to abductor digiti minimi was measured pre- and postoperatively in 15 patients. There was a significant improvement in MCTs in patients with myelopathy who improved clinically, but preoperative MCTs provided no clear, predictive information. Magnetic stimulation may be of value in quantifying motor function before and after surgery in patients with cervical spondylosis.

Prospective study of outcome of foramen magnum decompressions in patients with syrinx and non-syrinx associated Chiari malformations

Objective. To assess the outcome in patients with syrinx and non-syrinx associated Chiari malformations undergoing Foramen Magnum Decompression (FMD). Methods. Sixty-one patients undergoing FMD for Chiari malformations were prospectively studied with disease specific, generic (SF 36) and subjective (patient reported) outcomes. Of these, 34 patients had objective outcome data including SF36, visual analogue pain scores, Neck and Myelopathy disability indices and the Hospital anxiety and depression score. SF 36 scores were compared to normative data. Data were collected pre-operatively, at 3 months and during long-term follow up (12–60 months). Results. Patient reported improvements in headache and neck pain post-operatively was reported in both syrinx and non-syrinx associated patients. Visual Analogue scores showed improvements in arm pain, paresthesia and hand tingling at 3 months in the syrinx group only. Non-syrinx patients showed significant improvements post-operatively in the Neck disability index and the SF-36 domains for physical function, role physical and bodily pain. Comparison with SF-36 normative data indicates that patients still have significantly impaired quality of life 12 months post-operatively. Conclusion. FMD is able to relieve symptoms and improve quality of life in patients with both syrinx and non-syrinx associated Chiari malformations. In syrinx patients we observed symptomatic improvement in limb symptoms as well as radiological resolution of the syrinx. The use of SF-36 allows the health gain associated with FMD to be quantified. SF 36 is not adequate as a stand alone measure of outcome in this complex disorder and we advocate the concurrent use of disease specific measures and post-operative imaging of the syrinx.

Prospective study of outcomes in lumbar discectomy

Establishing standardized methods to assess outcome is needed to measure the effectiveness of surgery in relieving symptoms and improving quality of life. We prospectively studied 203 patients undergoing primary lumbar discectomy. Data was collected before surgery, at 3 months postoperatively and at long-term follow-up (12 – 60 months, median 24) using both disease-specific (visual analogue scores, Roland – Morris disability scales, and Hospital Anxiety and Depression scales) and generic (SF-36) instruments. Continued significant symptomatic benefit was observed to long-term assessment and the health gains in this patient group compared favourably with other elective surgical procedures. We have used this data to validate the SF-36 for use in this context and we recommend that SF36 should be used as a sole measure of outcome in routine practice, as well as in future studies.

An in vitro Study of the Pharmacological Responses of Rat Middle Cerebral Artery: Effects of Overnight Storage

This study was designed to establish the in vitro pharmacological responses of rat middle cerebral arteries (MCA), and also their susceptibility to overnight cold storage at 4 degrees C. MCAs were harvested from rats and pharmacological responses were studied using a Mulvany myograph. Responses to prostaglandin F2 alpha (PGF2 alpha), uridine triphosphate (UTP), noradrenaline (NA) and histamine were determined to investigate receptor-dependent responses, sodium nitroprusside and papaverine to investigate receptor-independent relaxation and L-arginine and N omega-Nitro-L-arginine methyl ester (L-NAME) to examine nitric oxide synthase-dependent responses. Responses in fresh arteries were established and compared with responses in arteries which had been mounted on a myograph and stored overnight at 4 degrees C before study the next day. The MCAs had an effective lumen diameter of 263 microns (SD 25) and sustained concentration-dependent contractions were produced by 124 mM K+, PGF2 alpha, UTP and L-NAME. Sodium nitroprusside, NA, histamine, papaverine and L-arginine produced concentration-dependent relaxations in precontracted arteries. Overnight cold storage did not alter the pharmacological responses to any of the agonists tested.

Psychological distress does not compromise outcome in spinal surgery.

Summary of background data. Physical outcomes following surgery for degenerative spine disease have been well studied whereas the importance of psychological factors has only recently been acknowledged. Previous studies suggest that pre-operative psychological distress predicts poor outcome from spinal surgery. In the drive to identify patients who will not benefit, these patients risk being denied surgery. Study design. This is a prospective series from a spinal surgical register. Aim. The study examines the relationship between the physical symptoms, pre-operative psychological distress and outcome following surgery. Methods. The Short Form 36 (SF36) Health Survey Questionnaire and the Hospital Anxiety and Depression Scale (HADS) were administered to patients undergoing elective surgery for degenerative spine disease pre-operatively and at 3 and 12 months post-operatively. Levels of physical disability (SF-36 physical functioning (SF36PF) and bodily pain (SF36BP) scores) and psychological distress (HADS-anxiety and HADS-depression scores) before and after surgery were compared. Results. A total of 302 patients were included (169 men, 133 women, mean age 55 years). Pre-operatively patients had worse physical scores than age-matched controls (SF36PF normative mean (S.D.) 80.97 (12.69) vs. pre-op 33.31 (24.7) P < 0.05). Of the 302 patients, 117 (39%) had significant anxiety or depression. Increased levels of anxiety or depression pre-operatively correlated with worse physical (SF-36PF and SF-36BP) scores pre-operatively (Spearmans r P < 0.05). Levels of anxiety and depression were reduced post-operatively and physical outcomes improved post-operatively. Physical function remained worse in those groups who had high levels of anxiety and depression pre-operatively but when matched for pre-operative physical function, psychological distress did not have any additional effect on outcome. Conclusions. Poor physical function pre-operatively correlates with psychological distress. Both physical and psychological symptoms improve after surgery. Physical outcome after surgery is strongly influenced by pre-operative physical functioning but not independently by psychological distress. Anxious and depressed patients should continue to be offered surgery if clinically indicated.

Combined radiological and surgical management of spinal dural fistulas

Abstract Introduction. Spinal Dural Fistulas (SDAVF) are the most common Spinal Vascular Malformation. The management of SDAVFs involves diagnosis and localisation with MRI and spinal angiography and subsequent embolisation or surgical interruption. We report our experience in treating these fistulas in which we undertake endovascular treatment, if technically feasible, with recourse to surgery only if occlusion is not possible. Method. This retrospective study reviews the management of 38 patients treated for SDAVFs over a 13-year period (1997–2010). Patient demographics, procedure and follow-up over a 6–12-month period (mean of approximately 10 months) were analysed and a qualitative assessment of patient outcome was made. Results. Patient ages ranged from 20 to 86 (mean 63.5), with 27 male and 11 female patients. A total of 28 patients managed with a combination of embolisation and surgery report either with improved symptoms or a return to normal. The presence of bladder and bowel symptoms indicated more severe disability and their presence at presentation was associated with lack of improvement following treatment. Conclusions. We report a treatment strategy for SDAVF involving primary endovascular intervention and reserving surgery for those patients in whom endovascular treatment is not possible.