The effect of prone positioning on intraocular pressure in anesthetized patients.

BACKGROUND: Ocular perfusion pressure is commonly defined as mean arterial pressure minus intraocular pressure (IOP). Changes in mean arterial pressure or IOP can affect ocular perfusion pressure. IOP has not been studied in this context in the prone anesthetized patient. METHODS: After institutional human studies committee approval and informed consent, 20 patients (American Society of Anesthesiologists physical status I-III) without eye disease who were scheduled for spine surgery in the prone position were enrolled. IOP was measured with a Tono-pen XL handheld tonometer at five time points: awake supine (baseline), anesthetized (supine 1), anesthetized prone (prone 1), anesthetized prone at conclusion of case (prone 2), and anesthetized supine before wake-up (supine 2). Anesthetic protocol was standardized. The head was positioned with a pinned head-holder. Data were analyzed with repeated-measures analysis of variance and paired t test. RESULTS: Supine 1 IOP (13 +/- 1 mmHg) decreased from baseline (19 +/- 1 mmHg) (P < 0.05). Prone 1 IOP (27 +/- 2 mmHg) increased in comparison with baseline (P < 0.05) and supine 1 (P < 0.05). Prone 2 IOP (40 +/- 2 mmHg) was measured after 320 +/- 107 min in the prone position and was significantly increased in comparison with all previous measurements (P < 0.05). Supine 2 IOP (31 +/- 2 mmHg) decreased in comparison with prone 2 IOP (P < 0.05) but was relatively elevated in comparison with supine 1 and baseline (P < 0.05). Hemodynamic and ventilatory parameters remained unchanged during the prone period. CONCLUSIONS: Prone positioning increases IOP during anesthesia. Ocular perfusion pressure could therefore decrease, despite maintenance of normotension.

Myelopathy induced by a thoracic intraspinal synovial cyst: case report and review of the literature.

STUDY DESIGN: A follow-up study of a patient with myelopathy resulting from a thoracic intraspinal synovial cyst was conducted. OBJECTIVE: To present this unusual form of myelopathy, and to highlight this unique condition by a literature review. SUMMARY OF BACKGROUND DATA: Intraspinal synovial cysts are quite common in the lumbar spine, but much rarer in the thoracic spine, where they may produce myelopathy from spinal cord compression. The reported patient presented with a lumbar degenerative spondylolisthesis, but actually was symptomatic from a thoracic synovial cyst. METHODS: Clinical and radiographic details of a patient with a thoracic intraspinal synovial cyst are presented. A complete literature review also summarizes previously published material on this topic. RESULTS: The thoracic intraspinal synovial cyst was appropriately identified on a magnetic resonance image examination. The patient underwent successful thoracic spinal cord decompression with stabilization and fusion. The myelopathy resolved postoperatively. CONCLUSIONS: The possibility of a thoracic synovial cyst should be considered in the evaluation of pain associated with myelopathy.

Do football helmets reduce acceleration of impact in blunt head injuries?

UNLABELLED: Several recent studies suggest that acceleration of the head at impact during sporting activities may have a detrimental effect on cognitive function. Reducing acceleration of impact in these sports could reduce neurologic sequelae. OBJECTIVE: To measure the effectiveness of a regulation football helmet to reduce acceleration of impact for both low- and moderate-force impacts. METHODS: An experimental paired study design was used. Male volunteers between 16 and 30 years of age headed soccer balls traveling approximately 35 miles per hour bareheaded and with a helmet. An intraoral accelerometer worn inside a plastic mouthpiece measured acceleration of the head. The helmet also had an accelerometer placed inside the padding. For more forceful impacts, cadaver heads, both with and without helmets, were instrumented with intraoral (IO) and intracranial (IC) accelerometers and struck with a pendulum device. Simultaneous IO and IC accelerations were measured and compared between helmeted and unhelmeted cadaver heads. The main outcome was mean peak acceleration of the head and/or brain associated with low- and moderate-force impacts with and without protective headgear. RESULTS: Mean peak Gs, measured by the mouthpiece accelerometer, were significantly reduced when the participants heading soccer balls were wearing a helmet (7.7 Gs with vs 19.2 Gs without, p = 0.01). Wearing a helmet also significantly lowered the peak Gs measured intraorally and intracranially in cadavers subjected to moderate-force pendulum impacts: 28.7 Gs with vs 62.6 Gs without, p < 0.001; and 56.4 Gs with vs 81.6 Gs without, p < 0.001, respectively. CONCLUSIONS: A regulation football helmet substantially reduced the peak Gs associated with "heading" a soccer ball traveling at moderately high velocities. A helmet was also effective in reducing the peak acceleration both intraorally and intracranially for impacts significantly more forceful than heading a soccer ball.

The effect of nerve-root injections on the need for operative treatment of lumbar radicular pain. A prospective, randomized, controlled, double-blind study.

BACKGROUND: The purpose of the present study was to determine the effectiveness of selective nerve-root injections in obviating the need for an operation in patients with lumbar radicular pain who were otherwise considered to be operative candidates. Although selective nerve-root injections are used widely, we are not aware of any prospective, randomized, controlled, double-blind studies demonstrating their efficacy. METHODS: Fifty-five patients who were referred to four spine surgeons because of lumbar radicular pain and who had radiographic confirmation of nerve-root compression were prospectively randomized into the study. All of the patients had to have requested operative intervention and had to be considered operative candidates by the treating surgeon. They then were randomized and referred to a radiologist who performed a selective nerve-root injection with either bupivacaine alone or bupivacaine with betamethasone. The treating physicians and the patients were blinded to the medication. The patients were allowed to choose to receive as many as four injections. The treatment was considered to have failed if the patient proceeded to have the operation, which he or she could opt to do at any point in the study. RESULTS: Twenty-nine of the fifty-five patients, all of whom had initially requested operative treatment, decided not to have the operation during the follow-up period (range, thirteen to twenty-eight months) after the nerve-root injections. Of the twenty-seven patients who had received bupivacaine alone, nine elected not to have the operation. Of the twenty-eight patients who had received bupivacaine and betamethasone, twenty decided not to have the operation. The difference in the operative rates between the two groups was highly significant (p < 0.004). CONCLUSIONS: Our data demonstrate that selective nerve-root injections of corticosteroids are significantly more effective than those of bupivacaine alone in obviating the need for a decompression for up to thirteen to twenty-eight months following the injections in operative candidates. This finding suggests that patients who have lumbar radicular pain at one or two levels should be considered for treatment with selective nerve-root injections of corticosteroids prior to being considered for operative intervention.

Visual loss after spine surgery: a survey.

OBJECTIVE: To survey a large number of neurosurgical spine surgeons for data regarding the presence of risk factors in patients experiencing visual loss after spine surgery. METHODS: A survey was sent to current members (as of 1997) of the American Association of Neurological Surgeons/Congress of Neurological Surgeons, Section on Disorders of the Spine and Peripheral Nerves, with questions focusing on intraoperative factors that may predispose patients to perioperative visual loss. RESULTS: Two hundred ninety surveys were returned, and 24 patients with visual loss after spine surgery were reported by 22 surgeons. Although many of these patients had probable causative factors for visual loss after surgery (e.g., hypotension, low hematocrit level, coexisting disease), some did not (n = 8). CONCLUSION: These results suggest the necessity of a high index of suspicion for evolving perioperative visual loss even in the absence of risk factors.

Cerebellar haemorrhage after evacuation of an acute supratentorial subdural haematoma.

Recent reports have highlighted the unusual complication of distant cerebellar haemorrhage after supratentorial craniotomy, with only 25 previous cases reported in the literature. Nearly all reported cases occurred after craniotomy for temporal lobectomy or for deep seated intracerebral pathology requiring brain retraction and removal of CSF at surgery. Only one previous case of a cerebellar haemorrhage after evacuation of an extracerebral fluid collection has been reported. We describe the case of a cerebellar haemorrhage complicating the evacuation of an acute/subacute supratentorial subdural haematoma in a 83-year-old woman. The literature is reviewed and possible mechanisms of haemorrhage discussed.

Complex cervical spine neoplastic disease: reconstruction after surgery by using a vascularized fibular strut graft. Case report.

The authors report a case of an aggressive chordoma in the cervical spine of a 15-year-old girl who underwent radical resection followed by reconstruction using an anterior vascularized fibular strut graft and posterior arthrodesis prior to receiving immediate postoperative radiation therapy. The patient had successful graft incorporation 4 months postoperatively. The authors review the advantages of using vascularized fibular strut grafts for the treatment of multilevel cervical spine neoplastic disease and discuss the theoretical advantages of using vascularized grafts that tolerate therapeutic levels of radiation.

Adjacent fracture-dislocations of the lumbosacral spine: case report.

OBJECTIVE AND IMPORTANCE: Traumatic fracture-dislocations of the lumbosacral junction are rare, with all previously reported cases involving fracture-dislocations at a single level. No cases of multiple fracture-dislocations of contiguous spinal segments in the lumbosacral spine have been reported. A case of traumatic adjacent fracture-dislocations of the fifth lumbar segment is presented. CLINICAL PRESENTATION: An 18-year-old male patient sustained open lumbar spinal trauma after a motor vehicle accident. A neurological examination revealed an L4 level. Radiographic evaluation of the spine revealed a three-column injury at L5 with spondyloptosis of the L5 vertebral body. Aorto-ilio-femoral angiography revealed no evidence of vascular injury. INTERVENTION: The patient was treated with a combined anterior and posterior approach in a two-stage operation. Six months postoperatively, he was neurologically unchanged; however, he was able to walk with the aid of a cane. Plain films revealed normal alignment of the lumbosacral spine. CONCLUSION: The management of traumatic lumbosacral fracture-dislocations requires careful consideration of retroperitoneal structures and possible exploration of the iliac vessels in addition to spinal reconstruction.

The safety of OP-1 for lumbar fusion with decompression-- a canine study.

OBJECTIVE: Bone morphogenetic proteins can serve as adjuncts to autologous bone to achieve bony fusion, and recombinant BMPs such as osteogenic protein-1 (OP-1) have the potential to replace autologous bone altogether as fusion substrate. However, relatively little is known about the safety of OP-1 for spinal fusion procedures. This study examined the effects of OP-1 intentionally placed in the subarachnoid space following thecal sac decompression, and used as graft substrate in a canine dorsolateral lumbar spine fusion model. METHODS: Lumbar decompression with dorsolateral fusion was performed on 30 canines. The dura was opened to simulate an intraoperative rent and OP-1 was placed in the subarachnoid space and in the fusion bed. Animals were sacrificed after 16 weeks and the spines were examined manually, radiographically and pathologically. RESULTS: All animals treated with OP-1 developed new bone in the subarachnoid space. This bone compressed the spinal cord, but no clinical or pathological features of neurotoxicity were noted. Mild spinal stenosis was noted at the site of dural decompression in the OP-1 treated animals. Over 80% of animals treated with OP-1 developed fusion as assessed by palpation (52% by CT criteria), while only 25% of control animals fused. CONCLUSIONS: Recombinant human OP-1 is effective at promoting fusion in a canine dorsolateral lumbar spine fusion model. However, bone growth can occur over exposed, decompressed dura, and it can form in the subdural and subarachnoid spaces. The use of OP-1 as an adjunct to spinal fusion appears to have merit, but its use must be carefully controlled to avoid unwanted bone formation and subsequent neural compression.

Pitfalls of bungee jumping. Case report and review of the literature.

A case of cervical spine injury related to bungee jumping is presented. Surgical intervention resulted in resolution of the patient's quadriparesis. The incidence of serious injury connected with this pastime is not inconsiderable, and it is recommended that safer jumping practices be followed. Inspection of bungee equipment and certification of instructors is now voluntary but should be mandated. Jumping heights should be limited and the use of air cushions encouraged.

Vertebral artery injury in C1-2 transarticular screw fixation: results of a survey of the AANS/CNS section on disorders of the spine and peripheral nerves. American Association of Neurological Surgeons/Congress of Neurological Surgeons.

OBJECT: The 847 active members of the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Section on Disorders of the Spine and Peripheral Nerves were surveyed to quantitate the risk of vertebral artery (VA) injury during C1-2 transarticular screw placement. METHODS: This retrospective study elicited the number of patients treated with transarticular screws, the number of screws placed, the incidence of VA injury and subsequent neurological deficit, and the management of known or suspected VA injury. Two hundred thirteen (25.1%) of the 847 surgeons responded. One hundred one respondents (47.4%) had placed a total of 2492 C1-2 transarticular screws in 1318 patients. Thirty-one patients (2.4%) had known VA injuries and an additional 23 patients (1.7%) were suspected of having injuries. However, only two (3.7%) of the 54 patients with known or suspected VA injuries exhibited subsequent neurological deficits and only one (1.9%) died of bilateral VA injury. Other iatrogenic complications included dural tears, screw fractures, screw breakout, fusion failure, infection, and suboccipital numbness. CONCLUSIONS: Including both known and suspected cases, the risk of VA injury was 4.1% per patient or 2.2% per screw inserted. The risk of neurological deficit from VA injury was 0.2% per patient or 0.1% per screw, and the mortality rate was 0.1%. The choice of management of intraoperative VA injuries was evenly divided between placing the patient under observation and initiating immediate postoperative angiography with possible balloon occlusion.

Preoperative treatment with botulinum toxin to facilitate cervical fusion in dystonic cerebral palsy. Report of two cases.

The authors report the use of high-dose botulinum toxin A for muscle relaxation prior to surgery for cervical spine fixation in two patients with dystonic cerebral palsy that included severe cervical dystonia. Both patients had recently developed progressive cervical myelopathy and surgery was planned to halt the insidious progressive weakness. However, marked dystonic posturing of the neck would have compromised their tolerance of halo fixation and subsequently impeded postoperative fusion. Preoperative chemodenervation of selected cervical muscles with injections of high-dose botulinum toxin A eliminated all involuntary neck movements, permitting the patients to tolerate halo fixation and facilitating postoperative spinal fusion. It is concluded that botulinum toxin A can be used safely and effectively in the preoperative management of patients with cervical dystonia and cervical spondylitic myelopathy.

Focal midbrain glioma: long term survival in a cohort of 16 patients and the implications for management.

BACKGROUND: Focal gliomas involving the midbrain tectum and tegmentum have been identified as having a better prognosis than diffuse tumors affecting the brain stem. However, only limited information is available concerning treatment effectiveness and long term outcome for these patients. METHODS: A retrospective, population-based cancer registry survey was performed to assess the clinical features and treatment courses of patients with focal midbrain tumors. RESULTS: Sixteen patients with midbrain gliomas were identified; eight had tectal gliomas and eight tegmental gliomas. Thirteen patients presented with symptoms related to hydrocephalus, and 12 required a ventriculoperitoneal shunt. Seven patients underwent surgery directed at the tumor. Eight patients underwent initial radiation therapy and none had initial chemotherapy. One patient diagnosed at age 18 months had a rapidly growing tumor after 14 months of follow up which has responded to chemotherapy. The mean survival of this patient population was 84 months (range 3-280 months) after diagnosis, with only one tumor related death occurring (280 months after diagnosis). Survival was not affected by tumor location within the midbrain (tegmental or tectal) or by whether radiation therapy was or was not administered. CONCLUSIONS: Patients with focal midbrain gliomas require symptom control aimed at treatment of hydrocephalus, or mass effect from the tumor. However the extended survival of this population suggests that routine aggressive surgical debulking is often not required. Furthermore, the routine use of radiation therapy or chemotherapy for all such patients is questioned.

Parapharyngeal branchial cleft cyst presenting with cranial nerve palsies.

The authors report a case of branchial cleft cyst for which the location and presentation of the lesion were unusual. This abnormality should be considered in the differential diagnosis of cystic lesions of the parapharyngeal space. The presence of multiple cranial nerve palsies in association with a mass in this region does not necessarily indicate a neoplastic lesion.

The acute orbit: differentiation of orbital cellulitis from subperiosteal abscess by computerized tomography.

A series of 65 patients suffering from acute inflammatory disease of the orbit was studied by CT. Ethmoiditis was the cause in the vast majority; trauma and dental extraction played a lesser role in causation. Orbital cellulitis was diagnosed in 17 and subperiosteal abscess in the remaining 48. It was not possible to differentiate 33 pus-containing abscesses from the six with inflammatory masses (phlegmons). The satisfactory response to aggressive medical treatment in those patients with inflammatory masses that were not drained justifies a more conservative approach; surgical drainage being reserved for those with a deterioration in proptosis, ocular movements or vision. Six abscesses arose de novo, of which some were in the orbital fat rather than the subperiosteal space.