The use of allograft (and avoidance of autograft) in anterior lumbar interbody fusion: a critical analysis.

The aim of this report is to analyze the validity of allograft in anterior lumbar interbody fusion. Forty-three patients underwent anterior lumbar interbody fusion using allograft in the period between 1995 and 1998. All suffered from crippling chronic low back pain with or without sciatica. Discogenic disease was verified in 40 cases by discography. All patients were investigated preoperatively with magnetic resonance imaging (MRI). The surgical technique is described. Follow-up radiographs were performed postoperatively, then at 1.5, 3, 6 and 12 months, as required. Radiological fusion was confirmed in all single-level fusions (100%, n=24). In two-level fusions the rate was 93% (n=28/30). However, radiological union could only be confirmed in 11 of the 12 levels in the three-level fusions. Allograft offers a better alternative to autograft for anterior lumbar interbody fusion. Donor site morbidity is avoided, hospital stay is shorter and fusion rates are satisfactory.

A rare complication of hardware failure in neurostimulation. Report of two cases.

The authors report on a rare complication of neurostimulation. Two patients presented with a skin rash after undergoing neurostimulator implantation, and the implants were found to have faulty electrical insulation. The rash was centered over the source of current leak and disappeared when the problem was corrected.

Early changes in middle cerebral artery blood flow velocity after head injury.

OBJECT: This study was designed to investigate the incidence of early abnormalities in the cerebral circulation after head injury by relating the results of the initial computerized tomography (CT) scan with transcranial Doppler (TCD) ultrasound readings to see if the side of injury and the outcome can be predicted by using these modalities. METHODS: Transcranial Doppler ultrasound measurements were obtained in the emergency room in 22 head-injured patients less than 3 hours after injury. The middle cerebral artery (MCA) was insonated using a standard technique. The TCD measurements in each MCA were examined individually; of 39 measurements, 22 (56%) showed a low mean blood flow velocity, 27 (69%) demonstrated a high pulsatility index (PI), and 18 (46%) showed both abnormalities. The side of the cerebrovascular abnormality measured by TCD ultrasound did not appear to be an accurate predictor of the side of the injury as determined on the initial CT scan. Of 13 patients in whom either a space-occupying hematoma or signs of swelling were shown on the initial CT scan, 10 (77%) had an increased PI in one or both MCAs, which is an indication of high flow resistance. CONCLUSIONS: Transcranial Doppler ultrasound examinations performed while patients are in the emergency room may have a role in determining treatment priorities, especially in those with multiple injuries.

The preoperative skin shave in neurosurgery: is it justified?

Shaving the scalp prior to surgery is a very common practice. Out of 105 cases operated upon without skin shave at the Royal London Hospital, only one became infected (0.95%). A search into the history of aseptic surgery shows that there are no scientific grounds for the practice of shaving. An examination of contemporary practices worldwide shows that there is a greater realization that preoperative skin shaving does not confer any benefit against postoperative wound infection and that, paradoxically, it may lead to higher rates of wound infection due to the epidermal injury that it inflicts.

Prospective study of zero drift in fiberoptic pressure monitors used in clinical practice.

One hundred and one fiberoptic pressure transducers (59 subdural and 42 ventricular) were studied in 86 patients (some in whom more than one device had been inserted). Only four complications occurred: two transient cerebrospinal fluid leaks after removal and two clinically insignificant intracerebral hematomas. No intracranial infections could be attributed to the devices. Technical problems occurred 23 times, with 11 devices ceasing to function before removal, seven becoming displaced, and five microventricular catheters failing to enter the ventricles. Zero-drift readings were obtained for 83 devices at the time of removal (median 66 hours after insertion, range 2 hours-13 days). There was a clear negative bias in the readings (median -3), with a wide range of values (-12 to +14 mm Hg; interquartile range -6 to -1) that was apparent even in the first 3 days of use. There was no important relationship between zero drift and any recorded variable. It is concluded that zero drift of fiberoptic pressure transducers is a significant problem and that undue reliance should not be placed on intracranial pressure readings from these devices in isolation from other clinical and radiological information.

Vertex extradural haematomas: a report of 3 cases and a review of the literature.

Extradural haematomas occurring at the vertex are an unusual group of a common condition. Their clinical presentation is frequently atypical and the diagnosis often delayed. The clinical findings do not always correlate with the site of the lesion and venous engorgement due to impaired venous drainage is the likely explanation. Nearly all cases will have a fracture crossing the vertex but this may go undetected as skull X-rays are frequently not performed in acute trauma and the vertex is a difficult area to visualize with conventional axial computed tomography (CT) scanning. Magnetic resonance image (MRI) scanning is the investigation of choice but is rarely available in acute trauma. Patients may present in an acute, subacute or chronic fashion. The treatment can be surgical or non-surgical depending on the neurological condition of the patient. Most patients make an excellent recovery.

'Efficient' timely evacuation of intracranial haematoma--the effect of transport direct to a specialist centre.

Patients with intracranial haematoma following head injury may have little primary brain injury, but sustain a secondary brain injury that can often be minimized by early evacuation of the haematoma. Rapid intervention by a neurosurgeon with early evacuation of the haematoma gives a better outcome. The timing of treatment in 403 patients with severe head injuries, admitted to the Royal London Hospital between January 1991 and December 1994 was examined. All cases had been transported directly from the accident scene by the Helicopter Emergency Medical Service because the local hospital did not have neurosurgical facilities. The median time to medical intervention was 15 min (95 per cent, confidence interval (CI) 14-16) and the median time to neurosurgery was 177 min (95 per cent, CI 171-195). As secondary interhospital transfer of patients with head injuries is known to increase the time to neurosurgical intervention and is a time of great risk of secondary insult to the brain, transfer direct from the scene of the accident to an appropriate centre allows a process of care that has been shown to be associated with a better outcome.

A prospective comparison of fibre-optic and fluid-filled single lumen bolt subdural pressure transducers in ventilated neurosurgical patients.

A clinical comparison was made between fibre-optic and fluid-filled Bolt subdural pressure transducers in ventilated head injured patients. Twelve subjects had both devices inserted in neighbouring sites. In two patients there were obvious technical problems with the fibre-optic system and the results were therefore excluded from further analysis. In the remaining 10 patients, 2167 pairs of simultaneous recordings were made for up to 9 days and the degree of correspondence studied. A quarter of paired readings differed by more than 5 mmHg. There was no evidence of any overall bias, but in individual patients one device often read higher or lower than the other. The proportion of closely corresponding readings tended to diminish after 4 days. Therapeutically relevant episodes, where treatment might have been initiated on the basis of the readings from only one of the two systems, were equally likely with both devices and occurred on average approximately every 30 h. The relative accuracy of the two devices remains uncertain, but there is evidence suggesting that both were prone to errors.

The role of emergency surgery in malignant spinal extradural compression: assessment of functional outcome.

The role of emergency surgery for spinal cord or cauda equina compression secondary to extradural metastases is assessed in terms of functional outcome in 84 cases. The records of patients with proven malignant extradural spinal compression were reviewed retrospectively to determine the influence of emergency versus elective decompressive surgery on functional outcome. A greater proportion undergoing emergency surgery, rather than electively (within 24 h) on the next list showed functional improvement, with recovered mobility (61.5% vs 25%). Overall, 70% of patients were mobile postoperatively. The findings suggest that despite initial delays in referral, and even if the patient is incontinent and immobile, emergency spinal decompression is justified.

Neurofibrillary tangles, but not Alzheimer-type pathology, in a young boxer.

The chronic neurological sequelae of boxing are well described, but there have been few neuropathological studies of boxers dying early in their career. We report the case of a 23-year-old boxer, whose brain showed neurofibrillary tangles in all neocortical areas, but remarkable sparing of medial temporal lobe structures. These tangles, assumed to be the result of repetitive head injury, were the only detectable abnormality: none of the other changes previously described in the brains of retired boxers were seen. The distribution and features of the neuropathological findings in this case suggest that the mechanism of tangle formation induced by repetitive head trauma may be different from that in Alzheimer's disease.

Mixed cranial nerve tumors in neurofibromatosis type 2.

Five cerebellopontine angle tumors from four patients with neurofibromatosis (NF) are described. Three were surgical resection specimens from patients with NF2 and two were removed at autopsy from a fourth patient who appears to have had a variant of NF2. On microscopy the three biopsy specimens appeared to be histologically mixed tumors: although they were predominantly typical benign schwannomas, the tumors also contained islands of meningioma, the two tumor types being closely intermingled. In our fourth patient, consecutive decalcified sections of the tumors in the petrous temporal bones revealed florid arachnoidal proliferation around both schwannomas. This had resulted in the formation of multiple "micromeningiomas", some of which had become partially incorporated into the tumor. There are a few previously reported examples of mixed schwannoma-meningiomas in the literature. Possible mechanisms for such a mixed tumor are discussed: the most likely explanation for the appearances in cases of apparently mixed vestibular nerve tumors is that reactive meningeal changes adjacent to the tumor are responsible. Arachnoidal proliferation appears to be more exuberant in bilateral acoustic neurofibromatosis than in sporadic acoustic schwannomas, possibly the result of a disease-related growth factor.

Subependymoma of the lateral ventricle: case report and literature review.

A case is presented of a 35-year-old man, who suffered intermittent hydrocephalic attacks due to a large subependymoma arising within the left lateral ventricle. The sparse literature on this rare tumour is reviewed.

Untoward clinical effects after stereotactic radiosurgery for intracranial arteriovenous malformations.

Stereotactic radiosurgery has become one of the most acceptable means of treating deep-seated intracranial arteriovenous malformations, as well as being a useful adjunct in a number of other pathologies. One hundred and sixty patients are discussed, having follow-up of at least 2 years. Radionecrosis occurred in six patients and haemorrhage in the latent period prior to thrombo-obliteration in a further six. Successful thrombo-obliteration was ultimately achieved in 76% of patients. As a bonus, epilepsy was improved in 29 of 48 patients presenting with seizures and worsened transiently in only three of these.

Do we need variable pressure shunts?

We describe our experience using a variable pressure cerebrospinal fluid shunting system, over a period of 5 years. These valves appear to be reliable and have the advantage of allowing pressure setting adjustments to be made in the out-patient clinic. An analysis of the cost-effectiveness of this system, allowing for materials, theatre time and hospital stay, suggests that over pounds 21,000 was saved, by avoiding shunt revision procedures, over this period.

Intraoperative ultrasound-guided biopsy of intracranial lesions: comparison with freehand biopsy.

Achieving the required accuracy during such relatively straightforward procedures as tumour biopsy or abscess aspiration remains a challenge especially for the more junior neurosurgeon. A study comparing freehand biopsy with ultrasound-guided biopsy is presented. The use of intraoperative ultrasound increases the accuracy at the expense of a slightly longer operating time. Diagnostic tissue was always obtained using this technique.

The value of intraoperative ultrasound in neurosurgery.

Intraoperative ultrasound is not a technique which has been widely accepted by neurosurgeons in this country, not least because bulky probes and machines become more of a hindrance than an asset in theatre. The development of new smaller probes, including ones small enough to visualize the brain through a conventional burr-hole has rekindled interest in this subject. Its use for guidance in tumour biopsy, cyst aspiration and catheter placement, as well as volume estimations and determining the completeness of tumour resection, are outlined. The ability to recognize peri-operative haemorrhage is demonstrated.

Gas gangrene occurring soon after compound depressed skull fracture.

Two cases of Clostridium perfringens infection occurring less than 24 hours after compound depressed skull fracture are reported. The infection was principally intracranial in the first and extracranial in the second; both required surgical debridement and antibiotic treatment. Attention is drawn to the rapidity with which a potentially life-threatening infection can develop in civilian head injury and to the implications for acute management of patients with compound depressed fractures.