Contribution of low-dose CT-scan protocols to the total positioning error in computer-assisted surgery.

PURPOSE: To quantify the contribution of a computed tomography (CT) scan to navigation accuracy in computer-assisted surgery. METHODS: Eighty-eight patients undergoing computer-assisted facial or skull-base surgery were fitted preoperatively with 4 to 12 markers, either attached to the skin (n = 20) or fixed in the osseous skull (micro-screws; n = 68). Low-dose high-resolution spiral CT was achieved with 25-cm field of view (FoV), 1-mm slice thickness, 2-mm table increment, 1-mm reconstruction interval, 140 kV, 40 mA, bony reconstruction algorithm, and 180 degrees reconstruction profile (effective slice thickness = 1.8 mm). During surgery, navigation accuracy was evaluated using two navigation systems. RESULTS: Mean error was 0.66 mm for osseous markers and 1.58 mm for cutaneous markers. Both values are markedly smaller than the effective slice thickness of the scan protocol used. Radiation exposure of the patient for the entire examination never exceeded that necessary for one single 10-mm slice in a standard brain examination. Despite the reduced dose, landmarks and fiducials were precisely identified in all cases. CONCLUSIONS: The CT-induced positioning error in the Z-axis is considerably reduced by overlapping raw data reconstruction. For 1-mm slices and a 25-cm FoV, the average scan-induced positioning error is about 0.3 mm. Spatial resolution is not affected by the low dose applied. For MRI-based navigation, a 1 mm3 voxel size is the best compromise between signal-to-noise ratio, spatial resolution and scan time.     

Treatment of immigrants and residents suffering from Neuro-Aids on a neurological intensive care unit: epidemiology and predictors of outcome

This study aimed at determining the clinical features and predictors for the outcome of patients with Neuro-Aids treated on a neurological intensive care unit (NICU) using retrospective analysis of all patients treated for Neuro-Aids in a tertiary Department of Neurology between 1996 and 2011. Chart review of the patients including the characteristics of intensive care was performed. As negative outcome, “death on the NICU or within 2 months following completion of NICU treatment” was defined. In total, 462 patients were identified of whom 87 were immigrants. 67 of all patients required NICU treatment (mean age 40.2 ± 0.8 years; 64 % male). The median of the duration between diagnosis of HIV infection and the onset of treatment on NICU was 8 days for immigrants and 10 years for residents (p < 0.001). 34 of the patients on the NICU died due to severe neuromanifestations. Negative predictors for death were: (1) artificial ventilation; (2) antiretroviral-naïve immigrant; (3) primary cerebral lymphoma; (4) missing antiretroviral therapy upon admission to the NICU. Gender, age, ethnicity, CD4+ cell count, and viral load were no predictors of a negative outcome. The results indicated that the rate of death during treatment on a NICU is much higher as compared with treatment on an internal medicine ICU. A lot of research and effort will be necessary to improve this outcome especially for immigrants with Neuro-Aids.     

Brainstem Auditory Evoked Potentials in Migraine-Evidence of Increased Side Differences During the Pain-Free Interval

Brainstem auditory evoked potentials (BAEPs) were recorded in 38 unselected patients (6 m./32 f.; age 18-54 yrs.) with various forms of migraine, during the pain-free interval. The values were compared to those of 50 control persons (18 m./32 f.; age 17-75 yrs.). Peak latencies (PL I-VI), interpeak latencies (IPL I-III, III-V, I-V) and side differences of all peaks (delta I-VI) were calculated. In contrast to PL's of migraine patients, all PL's of control persons were normally distributed. In 6 migraine patients (2 with basilar migraine) PL's were pathologically delayed. Statistical analysis did not show any significant difference in regard to PL's and IPL's between migraine patients and controls. However, side differences of all peaks (except peak IV,VI) were significantly increased in migraine patients as compared to controls. Our results indicate a slight but permanent impairment of brainstem function in migraine.     

Acetylsalicylic Acid vs. Metoprolol in Migraine Prophylaxis - A Double-Blind Cross-Over Study

In a double blind cross-over study, 28 patients, 5 male and 23 female, aged 31 +/- 14 years, after a run-in period of 8 weeks, were treated for 3 months with acetylsalicylic acid and for another 3 months with metoprolol, both in a prophylactic mode. Attack frequency was reduced significantly with both therapeutic regimens (ASA p less than 0.001, metoprolol p less than 0.00005). Reduction of attacks below 50% was seen with metoprolol in 14 cases, and with ASA in three cases. Even though ASA was of statistically significant efficacy in migraine prophylaxis, it clearly is not the drug of first choice in migraine prophylaxis.     

Paired stimulation and functional change of the sural nerve during beta blocker therapy

29 patients were examined during a therapy with beta blockers. The medication was applied over 12 weeks, 16 patients received propranolol 120 mg/day, 13 patients metoprolol 200 mg/day. Two patients showed side-effects. Neurophysiological examinations, i.e. sural nerve conduction velocity and paired stimulation of the sural nerve, revealed a slight decrease of nerve conduction velocity and a significant increase of the latency prolongation of the second nerve action potential when the medication was finished. These functional changes in the sural nerve may result from the interaction of metoprolol and propranolol with beta-receptors of the peripheral nerve.     

Headache Caused by a Sphenoid Mucocele but Presenting as an Ergotamine-Induced Headache

In a 65-year-old woman, symptomatic headache caused by a mucocele of the sphenoid sinus led to ergotamine abuse and subsequent ergotamine-induced headache. Since there were no neurological symptoms initially and the patient previously suffered from migraine, the mucocele was not recognized. Only after unsuccessful drug withdrawal therapy and an MRI, was the correct diagnosis made. Surgical removal of the mucocele led to complete relief of headache within 3 weeks. We conclude that ergotamine-induced headache can develop on the basis of symptomatic headache. In spite of the effectiveness of ergotamine tartrate, an MRI should be performed if focal neurological symptoms occur.     

Paraneoplastic subacute cerebellar degeneration in Hodgkin's disease Report of three cases and review of the literature

12 cases of paraneoplastic cerebellar degeneration with Hodgkin's disease have so far been reported. Three additional patients (Stage II-IA / IIA / IIIB) are presented. Although CT and MR-imaging (MRI) revealed a marked cortical atrophy of the cerebellum, there was no evidence of direct brain involvement. After irradiation and chemotherapy all patients showed a complete remission. There was no evidence of primary disease after an observation period of 3/2/5 years. Cerebellar symptoms also showed a partial remission.

As compared to the literature, our treatment appears to be more favourable, probably due to the fact, that therapy was more aggressive than usual.