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Skull Base. 2003 November; 13(4): 247–249.
PMCID: PMC1131859

Current Abstracts

DIAGNOSIS

A. Mohyuddin, E.A. Vokurka, D.G.R. Evans, R.T. Ramsden, A. Jackson. Is clinical growth index a reliable predictor of tumor growth in vestibular schwannomas? Clin Otolaryngol 2003;28:85–90

We have assessed the clinical growth index as an indicator of tumor growth rate in 50 patients with a vestibular schwannoma. Clinical growth index was calculated by measuring the length of history and dividing it by the maximum tumor diameter. Total tumor volumes were also measured from all MRI examinations and an effective tumor volume doubling time was calculated. Radiological growth measurements demonstrated involution in 10/50 patients. The median volume doubling time was 1.65 years (range 20.9–46.3 months, skewness 1.72 years). The median clinical growth index was 0.030 cm per month (range 0–0.270 cm per month, skewness 2.398). There was no significant correlation between volume doubling time and clinical growth index. Identification of rapidly growing tumors with clinical growth index > 0.025 cm/month had a positive predictive value of 61 %, negative predictive value of 48 %, false–positive rate of 30 % and false–negative rate of 52 %. In conclusion, we have shown that the growth rate of vestibular schwannoma is not related to the clinical growth index and we recommend that this measure should be abandoned in the clinical management of patients, where conservative management regimes are being considered.

DISEASE PROCESS

Robert K. Jackler, Michael Cho. A new theory to explain the genesis of petrous apex cholesterol granuloma. Otol Neurotol 2003;24:96–106

Objective: To propose a new hypothesis that attempts to explain the pathogenesis of pectrous apex cholesterol granuloma (PA CG).

Classic Obstruction–Vacuum Hypothesis: PA CGs form when mucosal swelling blocks the circuitous pneumatic pathways to the apical air cells. Trapped gas resorption results in a vacuum that triggers bleeding, and CG forms through anaerobic breakdown of blood products.

Problems with the Classic (Obstruction–Vacuum) Hypothesis: Impaired ventilation of mucosa–lined pneumatic tracks in the middle ear, mastoid, paranasal sinuses, and lung are very common, but CG is rare. The extraordinary levels of temporal bone pneumatization typically observed in PA CG cases is indicative of excellent ventilation and freedom from inflammatory mucosal disease. Were underpressure due to gas absorption alone sufficient to trigger hemorrhage, CG ought to be frequent in otitis media with effusion.

Patients: The opposite PA of 13 patients with PA CG compared with 31 highly pneumatic PAs in patients undergoing imagery for nonotologic reasons.

Main Outcome Measure: The nature of the bony partition, as seen on computed tomography, between the PA air cell system and the adjacent marrow compartment.

Results: 4 of 13 PAs with CGs on the opposite side showed deficient septation between air cells and marrow, whereas this was not observed in any of the 31 extensively pneumatized normal ears.

New Hypothesis (Exposed Marrow): As cellular tracts penetrate the apex during young adulthood, budding mucosa invades and replaces hematopoietic marrow. The bony interface becomes deficient, with couplation of richly vascular marrow and the mucosal air cell lining. Hemorrhage from the exposed marrow coagulates within the mucosal cells and occludes outflow pathways. Sustained hemorrhage from exposed marrow elements provides the engine responsible for the progressive cyst expansion. As the cyst expands, bone erosion increases the surface area of exposed marrow along the cyst wall. This exposed marrow theory explains the unique proclivity of the healthy and well–pneumatized PA to form a CG.

TREATMENT OUTCOMES

Yoshiyasu Iwai, Kazuhiro Yamanaka, Tomoya Ishiguro. Gamma knife radiosurgery for the treatment of cavernous sinus meningiomas. Neurosurgery 2003;52:517–524

Objective: We report on the efficacy of gamma knife radiosurgery for cavernous sinus meningiomas.

Methods: Between January 1994 and December 1999, we used gamma knife radiosurgery for the treatment of 43 patients and cavernous sinus meningiomas. Forty–two patients were followed up for a mean of 49.4 months (range, 18–84 mo). The patients' average age was 55 years (range, 18–81 yr). Twenty–two patients (52 %) underwent operations before radiosurgery, and 20 patients (48 %) underwent radiosurgery after the diagnosis was made by magnetic resonance imaging. The tumor volumes ranged from 1.2 to 101.5 cm3 (mean, 14.7 cm3). The tumors either compressed or were attached to the optic apparatus in 17 patients (40.5 %). The marginal radiation dose was 8 to 15 Gy (mean, 11 Gy), and the optic apparatus was irradiated with 2 to 12 Gy (mean, 6.2 Gy). Three patients with a mean tumor diameter greater than 4 cm were treated by two–stage radiosurgery.

Results: Thirty–eight patients (90.5 %) demonstrated tumor growth control during the follow–up period after radiosurgery. Tumor regression was observed in 25 patients (59.5 %), and growth was unchanged in 13 patients (31 %). Regrowth or recurrence occurred in four patients (9.5 %). The actual tumor growth control rate at 5 years was 92 %. Only one patient (2.4 %) experienced regrowth within the treatment field; in other patients, regrowth occurred at sites peripheral to or outside the treatment field. Twelve patients (28.6 %) had improved clinically by the time of the follow–up examination. None of the patients experienced optic neuropathy caused by radiation injury or any new neurological deficits after radiosurgery.

Conclusion: Gamma knife radiosurgery may be a useful option for the treatment of cavernous sinus meningiomas not only as an adjuvant to surgery but also as an alternative to surgical removal. We have known it to be safe and effective even in tumors that adhere to or are in close proximity to the optic apparatus.

OUTCOMES

Sara Axelsson, Sven Lindberg, Anna Stjernquist–Desatnik. Outcome of treatment with valacyclovir and prednisone in patients with Bell's palsy. Ann Otol Rhinol Laryngol 2003;112:197

Idiopathic facial paralysis, or Bell's palsy, shows a nonepidemic pattern that might indicate reactivation of a latent microorganism such as herpes simplex type 1 as a causative agent. Thirty percent of patients with Bell's palsy given no treatment will not recover completely, and 5 % will have severe sequelae. The aim of this study was to find out whether treatment with an antiviral drug in combination with corticosteroids is more effective than no medical treatment at all in patients with Bell's palsy. Fifty–six consecutive adult patients attending the otorhinolaryngology department of the University Hospital of Lund from 1997 to 1999 were treated with 1 g of valacyclovir hydrochloride 3 times per day for 7 days and 50 mg of prednisone daily for 5 days, with the dose being reduced by 10 mg daily for the next 5 days. Fifty–six adult patients with Bell's palsy attending the same department between 1995 and 1996 who were given no medical treatment were studied retrospectively and used as the control group. Forty–nine patients (87.5 %) in the treatment group recovered completely, as compared with 38 patients (68 %) in the control group (p < .05). One patient (1.8 %) in the treatment group displayed severe sequelae, defined as a House–Brackmann score of IV or worse, as compared with 10 of 56 patients (18 %) in the control group (p < .01). Among patients over 60 years old, 10 of 10 in the treatment group had complete recovery, as compared with 5 of 12 patients in the control group (p < .01). The present study showed a significantly better outcome in patients with Bell's palsy treated with valacyclovir and prednisone as compared with patients given no medical treatment. This difference in outcome was especially pronounced among elderly patients.

OUTCOMES/DIAGNOSIS

Dominik Brors, Maria Schäfers, Daniel Bodmer, Wolfgang Draf, Gabriele Kahle, Bernhard Schick. Postoperative magnetic resonance imaging findings after transtemporal and translabyrinthine vestibular schwannoma resection. Laryngoscope 2003; 113:420–426

Objectives/Hypothesis: Magnetic resonance imaging (MRI) has become the investigation of choice to follow up patients after vestibular schwannoma resection.

Study Design: Retrospective.

Methods: Postoperative MRI findings of 70 patients after vestibular schwannoma resection through a transtemporal (n = 48) and a translabyrinthine (n = 22) approach were reviewed. Time–dependent changes in intensity, size, and shape of enhancement in the internal auditory canal before and after contrast administration, postoperative temporal lobe gliosis, and changes of fat grafts were evaluated.

Results: After vestibular schwannoma resection, all patients showed signal enhancements in the internal auditory canal ranging from a faint to high signal intensity in the first postoperative MRI 3 to 6 months after surgery. In the next MRI at 12 to 24 months after surgery, 30 patients (43 %) showed a decreased signal, 35 patients (50 %) a stable enhancement, and 5 patients (7 %) an increased enhancement in the internal auditory canal depicted as an intense nodular or mass–like pattern. In patients with decreased or stable enhancement, a residual tumor could be excluded in the following MRI scans, whereas in all patients with increased enhancements after 12 to 24 months, signal enhancement further increased and residual tumors were detected. Different degrees of temporal lobe gliosis were found in 15 of 48 cases (31 %) after transtemporal tumor removal. Enhancement of fat grafts used in 22 cases decreased to different degrees in 14 cases (64 %).

Conclusions: Differentiation of residual tumor from scar tissue in the internal auditory canal after vestibular schwannoma resection requires close, long–term follow–up. Nodular and progressive enhancements in the internal auditory canal indicate residual tumor. Linear enhancement in the internal auditory canal has been found to be a common finding after vestibular schwannoma resection not associated with residual tumor.


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