The end-tidal carbon dioxide partial pressure (PCO2) response curves for the flow velocity in the middle cerebral artery were studied in 31 normal subjects with transcranial Doppler techniques. An exponential curve with an exponent of 0.034 mm Hg-1 was found to be a good fit to the recorded data. By means of this relationship, recordings of flow velocity in cerebral arteries can be normalized to a standard value of PCO2. Physiological aspects of cerebrovascular reactivity to PCO2 and the clinical implications of the PCO2 response curve are discussed. The normal material provides a reference for assessing pathological responses.

The results of the study support the hypothesis that normobaric hyperoxia in patients with severe TBI improves the indices of brain oxidative metabolism. Based on these data further mechanistic studies and a prospective randomized controlled trial are warranted.

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Object The need for interbody fusion or stabilization after anterior cervical microdiscectomy is still debated. The objectives of this prospective randomized study were 1) to examine whether combined interbody fusion and stabilization is more beneficial than microdiscectomy only (MDO) and 2) if fusion is found to be more beneficial than MDO, to determine which is the best method of fusion by comparing the results achieved using autologous bone graft (ABG), polymethylmethacrylate (PMMA) interposition, and threaded titanium cage (TTC). Methods A total of 125 patients with a single-level cervical disc disease were included in this prospective study. All patients were randomized and assigned to one of the four following groups: Group 1 (33 patients), MDO; Group 2 (30 patients), microdiscectomy followed by ABG; Group 3 (26 patients), microdiscectomy followed by injection of PMMA; and Group 4 (36 patients), microdiscectomy followed by placement of a TTC. Clinical outcome according to Odom criteria was summarized as 1) excellent and good or 2) satisfactory and poor. One-year follow-up examination was performed in 123 patients. Patients in the TTC group experienced a significantly better outcome 6 months after surgery (92% excellent and good results) compared with those in the MDO and ABG groups (72.7 and 66.6% excellent and good results, respectively). Twelve months after surgery there was still a significant difference in outcomes between the TTC group (94.4% excellent and good results) and the MDO group (75.5% excellent and good results). Outcome in patients treated with PMMA was comparable with that in those treated with TCC after 6 (91.6%) and 12 months (87.5%), but no segmental fusion was achieved. Differences compared with MDO and ABG were, however, not significant, which may be related to the smaller number of patients in the PMMA group. Conclusions Interbody cage-assisted fusion yields a significantly better short- and intermediate-term outcome than MDO in terms of return to work, radicular pain, Odom criteria, and earlier fusion. In addition, the advantages of interbody cages over ABG fusion included better results in terms of return to work, Odom criteria, and earlier fusion after 6 months. These results suggest that interbody cage–assisted fusion is a promising therapeutic option in patients with single-level disc disease. Polymethylmethacrylate seems to be a good alternative to interbody cage fusion but is hindered by the absence of immediate fusion.

The extended anterior subcranial approach differs significantly from more traditional surgical approaches to the skull base in that it allows a broad inferior access to the anterior skull base planes with tumor exposure from below rather than via the transfrontal route. The authors initially used the subcranial approach in 1978 for the treatment of high-velocity skull base trauma and certain craniofacial anomalies. In 1980 they expanded the indications to include the combined neurosurgical-otolaryngological resection of various skull base tumors. Osteotomy of the frontonasoorbital external skeletal frame provides optimum anterior access to the orbital and sphenoethmoidal planes as well as to the nasal and paranasal cavities while avoiding frontal lobe retraction and the external facial incisions characteristic of transcranial and transfacial approaches. The improved visualization of the anterior skull base and clival-sphenoidal region facilitates en bloc tumor removal, optic nerve decompression, exposure of the medial aspect of the cavernous sinus, and watertight realignment of the anterior cranial base dura. In this report the authors present their experience over the past 13 years with 104 patients who underwent operation via the extended subcranial approach. Because extensive frontal lobe manipulation and external facial incisions are avoided with this approach, intensive care unit and overall hospital stay are reduced, related complications are minimized, and postoperative cosmetic appearance is enhanced. The extended anterior subcranial method is therefore an excellent alternative to traditional transfacial-transcranial skull base approaches for the removal of selected skull base tumors.

Results from 1,039 combined cervical and transcranial Doppler examinations are reported. Satisfactory transcranial signals were not found in 2.7% of the cases. Compared with angiography, the accuracy of transcranial criteria in assessing collateral flow over the circle of Willis was 94 and 88% for anterior and posterior circulation, respectively. The method also appeared very promising for detection of lesions of the intracranial arteries although the number of such cases with angiographic verification was limited in the present series. Arterial narrowing due to cerebral vasospasm was diagnosed with a sensitivity of 80%. In patients with ruptured intracranial aneurysms, an incidence of 93% arterial narrowing in basal cerebral arteries was found. Patients with subarachnold hemorrhage and no aneurysm on angiography also showed arterial narrowing with an incidence of 56%. It was possible to monitor the time course and severity of cerebral vasospasm. Arteriovenous malformations were characterized by Doppler findings of high velocities and low pulsatilities. These lesions were diagnosed with an accuracy of 95%. (Stroke 1987;18:1018-1024)

Closure of the sella turcica with a synthetic absorbable vicryl patch, gelatin foam, and fibrin glue after transsphenoidal surgery is safe and very effective in preventing postoperative CSF fistulas. The use of this technique obviates the need for a second surgical incision and shortens the operating time. Because of the progressive resorption of the substitute material, the interpretation of postoperative magnetic resonance studies was not significantly hindered.

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