Microanatomical Study of the Extradural Middle Fossa Approach for Preventing Cochlear Damage

OBJECTIVE: The objective is to describe the relationship of anatomical landmark required for the middle fossa approach to preservation of hearing. METHODS: Dissection of 16 fixed human cadaveric heads was performed. we identified a rhomboid-shaped middle fossa landmarks that serve as a guide to minimize cochlea injury. The points of this construct are as follows ; 1) the junction of the greater superficial petrosal nerve and the trigeminal nerve ; 2) the lateral edge of the porus trigemius ; 3) the intersection of the petrous ridge and arcuate eminence ; and 4) the intersection of the lines extended along the axes of the greater superficial petrosal nerve and arcuate eminence. Mean, minimum, and maximum measurements of all distances were determined. RESULTS: The average cochlea-geniculate ganglion distance measured in the dissected specimens was 3.0+/-0.8mm with a range of 1.2 to 4.1mm. The average cochlea-petrous carotid genu distance was 2.9+/-0.9mm with a range of 1.2 to 4.0mm. The average cochlea-internal acoustic meatus distance measured in the dissected specimens was 9.0+/-0.5mm with a range of 7.8-10.9mm. The average cochlea-mandibular nerve distance measured was 9.4+/-0.4mm with a range of 7.6-11.3mm. CONCLUSION: The middle fossa approach requires special knowledge of the anantomy to reduce the risk of damage to cochlea. It is important that the surgeon understand the surgical anantomy. The present study describes the simple geometric construct that proposes to assist in locating the cochlea.

Modified Decompressive Craniotomy for Control of Intracranial Pressure

OBJECTIVE: Various surgical techniques were developed for control of intracranial pressure such as extraventricular drainage, temporal lobectomy or decompressive craniectomy. We now describe our clinical experience by using the modified decompressive craniotomy. METHODS: Modified decompressive craniotomy was performed in 8 patients with severe cerebral edema from July 2000 to April 2001. The indication of this operation was severe intracranial hypertension and edema in operative field. We analyzed the result(Glasgow coma scale, GCS score, Glasgow outcome scale, GOS score) with the variables(age, sex, mid line shift on brain computed tomography scan) RESULTS: The overall rate of good recovery(GOS score 4 or 5) was 75%(6 of 8 patients), poor recovery(GOS score 2 or 3) was 12.5%(1 of 8 patients), and mortality rate was 12.5%(1 of 8 patients). All of survived patients had improved GCS score(mean: 10.02) compared to preoperative GCS score(mean: 7.82). CONCLUSION: The authors would like to recommend modified decompressive craniotomy for the patient of traumatic brain swelling in appropriate indication. This new operative technique has advantages such as decompressive effect and no need of delayed cranioplasty.

A Comparative Analysis of Endovascular Coiling and Surgical Clipping of Upper Basilar Artery Aneurysms

OBJECTIVE: Despite advances in both operative techniques (endovascular coiling or surgical neck clipping), management of basilar artery aneurysms has not been completed. The goal of this retrospective study is to evaluate endovascular coiling compared with surgical neck clipping of upper basilar artery aneurysms. METHODS: From january of 1990 to December of 2001, the authors treated 31 cases of upper basilar artery aneuryms. Among of those upper basilar artery aneurysms, 22 patients received surgical neck clipping and 9 patients recevied non-surgical endovascular coiling. Results from outpatient follow-ups for 12 months after operation were classified with Glasgow outcome scale (GOS) analyzed respectively. RESULTS: Overall, 11(50%) of the surgical neck clipping patients and 6(66.7%) in endovascular coiling patients were showed good outcomes(GOS 4~5). Morbidity of the surgical clipping is about 22.7%(5/22) and the endovascular coiling is about 22.2%(2/9) There were two death in the surgical clipping group due to vasospasm and brain stem infarction, but none in the endovascular coiling group. The major causes of surgical morbidity were direct brain damage, perforator occlusions, vasospasm and meningitis. Endovascular coiling group was shorter hospital stay and lesser hospital expenses than surgical neck clipping group. CONCLUSION: Non-surgical endovascular coiling of upper basilar artery aneurysms is considered to be useful alternative treatment in improving short-term prognosis(12 months follow-ups) and reducing medical expenses compared to surgical neck clipping although long-term follow-up is needed.