[Cochlear nerve continuity preservation during retrosigmoid ablative osteotomy of the internal auditory canal for advanced vestibular schwannomas]. / Kontinuitätserhalt des Nervus cochlearis bei der retrosigmoidalen ablativen Osteotomie des inneren Gehörgangs bei fortgeschrittenen Vestibularisschwannomen.

The data of 86 patients with retrosigmoid microsurgical resection of vestibular schwannoma in tumor stage Koos II-IV were evaluated. In more than two thirds of the cases it was shown that the cochlear nerve followed the facial nerve, which is easily identified by electroneurography, in recurrent similar patterns in the region of the internal auditory canal. Starting from the fundus, this facilitated early identification and thus preservation of continuity of the cochlear nerve in the course of the internal auditory canal. This was of particular importance when safe functional preservation could not be guaranteed due to tumor size or formation despite intraoperative derivation of somatosenoric potentials, but when the possibility of subsequent hearing rehabilitation with a cochlear implant should be granted. Preoperative MRI sequences gave an indication of the possible nerve courses in some cases, but intraoperative imaging in the internal auditory canal was superior to MRI.

[Subtle focal diffusion abnormality in the hippocampus]. / Subtile fokale Diffusionsstörung im Hippokampus.

A 53-year-old female patient presented with sudden onset confusion and disorientation. Further neurological examination was unremarkable and the patient showed a complete recovery after several hours. A magnetic resonance imaging (MRI) examination performed 2 days later revealed a tiny focal lesion in the lateral hippocampus in the diffusion weighted images consistent with transient global amnesia.

A comparative study of perfusion CT and 99m Tc-HMPAO SPECT measurement to assess cerebrovascular reserve capacity in patients with internal carotid artery occlusion.

BACKGROUND AND PURPOSE: Patients with internal carotid artery (ICA) occlusion can demonstrate impaired cerebral vascular reserve (CVR). The detection of CVR using single photon emission CT (SPECT) is nowadays widely accepted as a predictor in the diagnostic pathway in patients considered for cerebral revascularization. Recently perfusion CT (PCT) gained widely acceptance in stroke imaging. The present study was aimed at comparing the results of perfusion CT (PCT) and 99m Tc-HMPAO SPECT with acetazolamide challenge in patients with ICA occlusion. METHODS: 13 patients were included in the prospective evaluation. Both PCT and 99m Tc-HMPAO SPECT were performed before and after the administration of acetazolamide. In detail, regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), adapted time to peak (Tmax) and mean transit times (MTT) were compared with SPECT data. - RESULTS: 99m Tc-HMPAO SPECT demonstrated an impairment of CVR in six patients. A preserved CVR was present in seven patients. All patients with impaired CVR proven by SPECT had a delayed MTT (mean +2.98 s) and a delayed Tmax (mean + 5.9 s), (both p <0.005 compared with the non occluded side). 66% of patients with impaired CVR in SPECT showed a complete correlation of Tmax measurements in PCT with a high positive predictive value (PPV: 88.8%). - CONCLUSION: The prospective study demonstrated a highly significant correlation of perfusion parameters as detected by 99m Tc-HMPAO SPECT and the Tmax as detected by PCT in patients with ICA occlusion. Therefore this easy-to-perform technique seems to be an adequate method for the evaluation of cerebral perfusion in patients with ICA occlusion.

[Neuroradiologic diagnostic and interventional procedures for diseases of the skull base]. / Neuroradiologische Diagnostik und Interventionen bei Prozessen an der Schädelbasis.

Besides image-guided biopsy techniques, the emphasis in the interdisciplinary cooperation between head and neck surgery and neuroradiology is on vessel-occluding and preserving measures. Knowledge of dangerous anastomoses between extracranial and intracranial vessels is crucial. The principles of vessel-occluding procedures including materials are presented and illustrated with case examples. Embolization of glomus tumors or epistaxis and preoperative permanent vessel occlusion techniques are demonstrated as well as vessel-preserving therapies, such as placement of covered stents for improving tumor resectability or after iatrogenic laceration of the internal carotid artery.

MTT Heterogeneity in Perfusion CT Imaging as a Predictor of Outcome after Aneurysmal SAH.

BACKGROUND AND PURPOSE: Impairment of tissue oxygenation caused by inhomogeneous microscopic blood flow distribution, the so-called capillary transit time heterogeneity, is thought to contribute to delayed cerebral ischemia after aneurysmal SAH but has so far not been systematically evaluated in patients. We hypothesized that heterogeneity of the MTT, derived from CTP parameters, would give insight into the clinical course of patients with aneurysmal SAH and may identify patients at risk of poor outcome. MATERIALS AND METHODS: We retrospectively analyzed the heterogeneity of the MTT using the coefficient of variation in CTP scans from 132 patients. A multivariable logistic regression model was used to model the dichotomized mRS outcome. Linear regression was used to eliminate variables with high linear dependence. T tests were used to compare the means of 2 groups. Furthermore, the time of the maximum coefficient of variation for MTT after bleeding was evaluated for correlation with the mRS after 6 months. RESULTS: On average, each patient underwent 5.3 CTP scans during his or her stay. Patients with high coefficient of variation for MTT presented more often with higher modified Fisher (P = .011) and World Federation of Neurosurgical Societies grades (P = .014). A high coefficient of variation for MTT at days 3-21 after aneurysmal SAH correlated significantly with a worse mRS score after 6 months (P = .016). We found no correlation between the time of the maximum coefficient of variation for MTT after bleeding and the patients' outcomes after 6 months (P = .203). CONCLUSIONS: Heterogeneity of MTT in CTP after aneurysmal SAH correlates with the patients' outcomes. Because the findings are in line with the pathophysiologic concept of the capillary transit time heterogeneity, future studies should seek to verify the coefficient of variation for MTT as a potential imaging biomarker for outcome.

[Diagnostic work-up and therapy of spinal vascular malformations: an update]. / Diagnostik und Therapie der spinalen vaskulären Malformationen: Ein Update.

INTRODUCTION: Spinal vascular malformations are rare disease patterns with a clinical incidence of about 5-10/year/1 million comprising spinal arteriovenous malformations (sAVM), spinal arteriovenous fistulas (sAVF) and spinal cavernomas. Long courses of disease before diagnosis deteriorate the prognosis despite successful treatment. METHODS: Selective review of the literature in consideration of present guidelines. RESULTS: Spinal vascular pathological conditions can be classified into different subtypes especially by use of magnetic resonance imaging (MRI) and selective digital subtraction angiography (DSA). Diagnosis and treatment of spinal dural arteriovenous fistula (type I) as well as spinal arteriovenous malformations (type II-V) ideally require a close co-operation between neurosurgeons and neuroradiologists. Surgery can in general be considered as curative. Endovascular therapy of arteriovenous malformations results in reduction of size and concomitant haemodynamic effects. A curative approach is generally not possible. Particularly in cases of lumbosacral and craniosacral arteriovenous fistulas the interventional procedure provides advantages. Treatment of spinal cavernomas nowadays consists of neurosurgical approaches exclusively. The significance of radiosurgical therapy, especially with the CyberKnife, remains indistinct. Today, interdisciplinary neurosurgical and neuroradiological co-operation in specialized centres allows most spinal vascular malformations to be diagnosed at an early stage and to be treated with satisfying results.

[Modification of the retrolabyrinthine approach with hearing preservation in CPA tumors]. / Modifizierter retrolabyrinthärer Zugangsweg bei Kleinhirnbrückenwinkeltumoren zum Hörerhalt.

BACKGROUND: In an anatomical study including a CT scan of the cadaver sections by means of a virtual model analysis the option of a modified retrolabyrinthine passage to the cerebellopontine angle (CPA) preserving the Saccus endolymphaticus and the upper petrosus sinus was analysed. METHODS: Due to the individual anatomical variations of the petrosus bone the results showed several limitations with regard to the retrolabyrintine passage to the CPA. The smallest distance between the dura of the posterior fossa and the posterior semicircular canal measured in a high resolution CT was of particular importance as to how much room was available for the surgical manipulation in the retrolabyrinthine space. As the back side angle to the petrosus bone is much flatter in a translabyrinthine approach than in a retrosigmoidal approach the internal auditory canal needed to be controlled by using a 30 degree endoscope. RESULTS: In five patients the translabyrinthine approach was modified by temporarily preserving the labyrinth in an effort to remove the CPA tumors. Based on our clinical experience and on the findings of the anatomical and radiological studies we eventually removed the CPA tumors type B2 or C3 in three patients preserving hearing by using a modified retrolabyrinthine approach.

Fetal MRI of the central nervous system: clinical relevance.

OBJECTIVE: Specific conditions of the mother sometimes reduce the quality of ultrasound. In these cases, fetal magnetic resonance imaging (MRI) can be performed after gestational week (GW) 18. Interpretation of subtle disorders or malformations becomes safe not before GW 23. Clinical development of children with central nervous system (CNS) disorders is not predictable with imaging alone. Statistical evidence and personal experience of the medical team are essential in counseling, but optimized imaging is helpful in being more precise. The value of fetal MRI (fMRI) is evaluated. MATERIALS AND METHODS: Twenty-five pregnant women (30.5 +/- 4.5 years) were investigated by additional fMRI. TECHNIQUE: Breath-hold technique with T2 half-Fourier acquisition single-shot turbo spin-echo and T1 FLASH-2D images in three dimensions with field of view of 350 x 400 mm. All cases have been correlated with postnatal MRI, ultrasound, and clinical follow-up. RESULTS: In all fetuses, diagnostic MRI was performed 3-10 days after ultrasound between GW 22 and 34 (GW 26.1 +/- 3.6). Sedation was not necessary. In eight cases of suspicious ultrasound, fMRI confirmed ultrasound findings. In 13 cases, additional diagnoses or exclusions of suspected findings could be established. Complete revision of diagnosis was realized in four cases. Findings could be confirmed by postnatal MRI in 11 patients. The clinical course was not predictable in cases with ambivalent prognosis. CONCLUSIONS: Prenatal diagnosis of CNS pathologies should result in parental counseling. Sufficient diagnostic information, statistical data, and experience of the involved professionals are essential. These results show that in detecting congenital CNS abnormalities fMRI is superior to ultrasound and should be considered in difficult cases.

[Significance of emissary veins in surgical treatment of temporal paragangliomas]. / Stellenwert emissarischer Venen bei der operativen Therapie temporaler Paragangliome.

With the surgical removal of temporal paraganglioma, possible changes of the cerebral blood pathways of the Circle of Willis should be considered. If the cerebral blood drains dominates unilaterally and the pathway of drainage over the Bulbus venae jugularis is inadequate due to vessel malformation or variations or by intraluminal tumor growth, as for instance of temporal paragangliomas, collateral emissary vessels can take over this function by an extraordinary large lumen extension. Ignorance of such a characteristic venous drainage can lead to hemorrhagic apoplexia when such originally redundant veins are sacrificed. A presurgical angiography is, therefore, indicated. In case of vessel malformations or variations the use of computer-assisted surgery could be helpful to preserve such native emissary veins at the bony skull base, such as the condylar emissary vein in the case of a transcondylar infralabyrinthine approach.

[Fetal MRI]. / Fetales MRT.

Ultrasonography is the method of choice for prenatal malformation screening, but it does not always provide sufficient information for correct diagnosis or adequate abnormality evaluation. Fetal MRI is increasingly being used to complete sonographic findings. It was initially used for evaluation of cerebral abnormalities but is increasingly being applied to other fetal areas. In vivo investigation of fetal brain maturation has been enhanced by MRI. An adequate analysis of fetal chest and abdomen can be achieved with fast T2-, T1-weighted and diffusion-weighted imaging (DWI). The advantages include the great field of view and the excellent soft tissue contrast. This allows correct diagnosis of congenital diaphragmatic hernia and evaluation of the consequences on pulmonary growth. Other pulmonary malformations, such as cystic adenomatoid malformation, sequestration and bronchogenic cysts, can also be easily identified. Renal position can be quickly determined using DWI sequences and renal agenesia can be easily diagnosed with only one sequence. Prenatal MRI is virtually as effective as postnatal examination, dispenses with transport of a potentially very ill newborn, and provides logistic advantages. Therefore, prenatal MRI is useful for adequate postnatal treatment of newborns with malformations.

[Cerebral perfusion computerized tomography in vasospasm after subarachnoid hemorrhage: diagnostic value of MTT]. / Die zerebrale Perfusions-Computertomografie beim Vasospasmus nach Subarachnoidalblutung: Diagnostischer Wert der MTT.

PURPOSE: Analysis of the value of the perfusion parameter mean transit time (MTT) for the diagnosis of cerebral vasospasm after Subarachnoid Hemorrhage (SAH). Comparison with other perfusion parameters. An MTT threshold indicating the necessity of conventional angiography will be defined. MATERIALS AND METHODS: We analyzed the CT Perfusion (CTP) of 20 patients suffering from SAH (Fisher grading 3 and 4). In each patient a baseline examination was performed the day after treatment of the ruptured aneurysm. Follow-up was indicated for the occurrence of clinical symptoms, pathologic Doppler values or the first day after endovascular therapy. The cortical mean transit time (MTT), T (max,) cerebral blood flow (CBF) and cerebral blood volume (CBV) were calculated. A vasospasm score resulting from the Doppler values and clinical neurological symptoms was compared to MTT in the follow-up. The outcome after discharge from the intensive care unit was compared to the maximum MTT. RESULTS: 18 patients were able to be evaluated. We found parallelism between the time course of MTT and clinical symptoms in 14 of 18 patients. In 4 of 18 patients no relationship between MTT and clinical symptoms was found. There is a good correlation between the clinical outcome at the time of discharge and the MTT. Clinical symptoms occurred if the MTT was between 3.2 and 4.0 s. An MTT above 4.0 s resulted in a bad clinical outcome. 9 of 18 patients showed angiographic criteria for endovascular treatment. All those patients showed an MTT of more than 3.2 s at the time of angiography. CONCLUSION: The analysis of the cortical perfusion parameter MTT is suitable for revealing clinically relevant global and regional vasospasm. A risk potential prediction is possible. An MTT of 3.2 s indicates a conventional angiography (DSA). This should be verified using a larger number of patients.

[Computerized analysis of brain perfusion parameter images]. / Automatisierte Analyse von Parameterbildern der Hirnperfusion.

PURPOSE: The development of a computerized method which allows a direct quantitative comparison of perfusion parameters. The display should allow a clear direct comparison of brain perfusion parameters in different vascular territories and over the course of time. The analysis is intended to be the basis for further evaluation of cerebral vasospasm after subarachnoid hemorrhage (SAH). The method should permit early diagnosis of cerebral vasospasm. MATERIALS AND METHODS: The Angiotux 2D-ECCET software was developed with a close cooperation between computer scientists and clinicians. Starting from parameter images of brain perfusion, the cortex was marked, segmented and assigned to definite vascular territories. The underlying values were averages for each segment and were displayed in a graph. If a follow-up was available, the mean values of the perfusion parameters were displayed in relation to time. The method was developed under consideration of CT perfusion values but is applicable for other methods of perfusion imaging. RESULTS: Computerized analysis of brain perfusion parameter images allows an immediate comparison of these parameters and follow-up of mean values in a clear and concise manner. Values are related to definite vascular territories. The tabular output facilitates further statistic evaluations. The computerized analysis is precisely reproducible, i. e., repetitions result in exactly the same output. CONCLUSION: Computerized analysis of brain perfusion parameters with Angiotux 2D-ECCET is objective and ensures reproducible results. It may become the basis and a requirement for the analysis of minimal changes in brain perfusion prior to irreversible damage from posthemorrhagic vasospasm.

Intracranial bilateral vertebral artery dissection during anticoagulation after cerebral venous and sinus thrombosis (CSVT).

A 37-year-old woman presented with cerebral venous and sinus thrombosis (CVST). During the period of anticoagulation she developed asymptomatic dissection of the intracranial segments of both vertebral arteries with an enlarging false aneurysm on the right side. Endovascular occlusion of the pathological segment of the right vertebral artery including the dissecting aneurysm and conservative management of the other side resulted in complete recovery without neurological complications.

[Indication for emergent revascularisation of acute carotid occlusion]. / Stellenwert der Revaskularisation eines akuten Karotisverschlusses.

BACKGROUND AND PURPOSE: We examined indications for emergent revascularisation of acutely occluded internal carotid artery (ICA) using current diagnostic methods. MATERIAL AND METHODS: From 1997 to 2006 we prospectively followed 34 consecutive patients undergoing emergency revascularisation due to acute extracranial ICA occlusion and acute ischaemic stroke within 72 h after symptom onset (mean 25) and within 36 h after admission (mean 16). Exclusion criteria were occlusion of the intracranial ICA or ipsilateral middle cerebral artery (MCA), ischaemic infarction of more than one third of the MCA perfusion area, or reduced level of consciousness. All patients underwent duplex sonography, cerebral CT, and/or MRI and angiography (MRA and/or DSA). We performed endarterectomy and thrombectomy of the ICA. RESULTS: Confirmed by postoperative duplex sonography at discharge, ICA revascularisation was successful in 30 (88%) of 34 cases. Postoperative intracranial haemorrhage was detected in two patients (6%) and perioperative reinfarction in one (3%). Compared to the preoperative status, 20 patients (59%) showed signs of clinical improvement by at least one point on the Rankin scale, ten patients (29%) remained stable, and two patients (6%) had deteriorated. The 30-day mortality was 6% (two patients). CONCLUSION: After careful diagnostic workup, revascularisation of acute extracranial ICA occlusion is feasible with low morbidity and mortality.

Timing of Mean Transit Time Maximization is Associated with Neurological Outcome After Subarachnoid Hemorrhage.

PURPOSE: Computed tomography perfusion (CTP) has gained significant relevance for the radiological screening of patients at risk of developing delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). Particularly, the impact of MTTPEAK, i.e., the maximal mean transit time value in a series of CTP measurements, for the prediction of long-term outcome has recently been demonstrated by our group. Complementing this recent work, the present study investigated how the timing of MTTPEAK affected the long-term outcome after aneurysmal subarachnoid hemorrhage. METHODS: CTP examinations from 103 patients with clinical deterioration attributed to DCI after aSAH were retrospectively analyzed for time interval between SAH ictus and onset of MTTPEAK in association with modified Rankin Scale (mRS) 23.1 months after SAH. RESULTS: Patients with unfavorable outcome (mRS > = 2) suffered significant earlier MTTPEAK onsets than patients with favorable outcome (mRS = 0 and 1). MTTPEAK within the first week was associated with significantly higher mRS scores compared to later MTTPEAK. Timing of MTTPEAK together with the value of MTTPEAK and initial World Federation of Neurosurgical Societies (WFNS) grade was a significant predictor for an unfavorable outcome (mRS > = 2). CONCLUSIONS: The current findings suggest a presumably higher vulnerability of the brain to early microcirculatory impairments after aSAH and highlight that timing of MTT elevations could be considered for the identification of patients at increased risk for poor neurological outcome due to DCI.

[Clinical and histopathological results after local chemoembolization of oral and oropharyngeal carcinoma--comparison with intraarterial chemoperfusion]. / Klinische und histopathologische Ergebnisse nach lokaler Chemoembolisation oraler und oropharyngealer Karzinome--Vergleich mit intraarterieller Chemoperfusion.

PURPOSE: Retrospective analysis of clinical and histopathological results after neoadjuvant intraarterial chemoembolization (iaCE) as compared to intraarterial chemoperfusion (iaCP) in patients with oral and oropharyngeal squamous cell cancer (SCC). MATERIALS AND METHODS: 289 patients (mean age 60 years, 68 % male) with SCC of the oral cavity or the oropharynx (WHO stage I-IV) received (1) neoadjuvant iaCE (n = 103) with a crystalline suspension of cisplatin (150 mg/m(2), solution ratio 5 mg cisplatin ad 1 ml NaCl 0.9 %, total volume 40 - 60 ml) or (2) iaCP (n = 186) using high-dose cisplatin infusions (150 mg/m(2), 1 mg cisplatin ad 1 ml NaCl 0.9 %, 400 - 500 ml). The decision for iaCE or iaCP was made individually for each patient based on tumor localization and expected vascular supply. Four weeks after local chemotherapy, the treatment response was evaluated according (1) to WHO criteria and (2) to histopathological TNM-grading after tumor resection. RESULTS: The overall treatment response was 72.5 % after iaCE and 47 % after iaCP (p < 0.001). A stable disease was found in 24 % and 48 %, respectively, and tumor progression was found in 3 % for both modalities. Histopathological examination of resected tumors revealed complete remission in 20 % after iaCE and 13 % after iaCP. The percentage of complete remissions was highest in local T1 and T2 tumors after iaCE (42.9 versus 22.4 % after iaCP, p = 0.031). Local side effects were significantly more frequent after iaCE than after iaCP (p < 0.001), especially in obese patients with extended carcinoma of the oral floor or the tongue base. CONCLUSION: Compared to iaCP, clinical and histopathological remission rates are significantly higher after iaCE, especially in early stages of local tumor growth. However, in view of the higher risk of regional complications, indication for iaCE should be considered cautiously and its application should be limited to small tumors of the oral floor and the oral tongue.

Intra-arterial high-dose chemotherapy with cisplatin as part of a palliative treatment concept in oral cancer.

BACKGROUND AND PURPOSE: Patients with cancer of the oral cavity often present with advanced tumor stages, distant metastasis, or severe comorbidities, which render radical surgery unfeasible. The purpose of this study was to investigate the response rate, technical feasibility, and safety of intra-arterial (IA) chemotherapy as palliative treatment in this situation. METHODS: From November 1997 to December 2003, 64 patients with histologically proven oral squamous cell carcinoma, classified as inoperable, received IA high-dose chemotherapy with cisplatin as a palliative treatment at our institution. To minimize toxic side effects, sodium thiosulfate was given intravenously. Twenty-eight percent of the patients were female; average age was 61.5 years. Clinical staging of primary tumors was TNM (tumor, nodules, metastases) stage IV in 89%, stage III in 6.3% and stage II in 4.7%. After local chemotherapy, additional radiation of the tumor area or radiochemotherapy was performed in 33 patients. RESULTS: There were no major catheter-related complications or severe side effects of IA chemotherapy. After the first cycle, 10% percent of the patients had complete remission (CR), 35% had partial response (PR), and 43.3% presented with stable disease. Mean follow-up interval was 11 +/- 12.9 months. Forty-five patients died after a mean period of 7.6 +/- 7.0 months (median, 5.1 months). The overall 1- and 2-year survival rates were 29.5% and 18%, respectively. There was a trend toward longer survival in patients who received subsequent radiation or radiochemotherapy after IA chemotherapy. CONCLUSION: IA chemotherapy in patients with inoperable carcinoma of the oral cavity as palliative treatment was technically feasible and safe. The overall response rate after IA chemotherapy was 45% (CR 10%; PR 35%). Side effects could be minimized by neutralizing the cytotoxic agent by sodium thiosulfate.