New mechanical thrombectomy model in the rabbit: A feasibility study.

BACKGROUND AND PURPOSE: Thrombolytic therapy represented the gold standard for the treatment of ischemic stroke. Its drawbacks include increased bleeding risk and low recanalization rates. Mechanical thrombectomy is a new promising therapy option. Devices used for this procedure were substantially improved during recent years. New devices require extensive preclinical invivo testing. We therefore sought to translate the commonly used pig model to a simplified and cheaper rabbit model. MATERIALS AND METHODS: We performed thromboembolisation in eight intubated and sedated adult female New Zealand white rabbits. The thrombus was created by careful rotation of autologous blood in a silicone tube and addition of barium sulfate for radiopacity. We injected the artificial thrombus via a catheter through the cannulated femoral artery. After thromboembolisation, 2D-DSA was performed to evaluate location and thrombus dimensions. COMPARISON WITH EXISITING METHOD(S): None. RESULTS: No complications or mortality were observed in our series. In seven cases (87.5%) the location of the thromboembolism was the maxillary artery and in one case (12.5%) the thrombus reached the occipital artery. The radiopaque thrombus had a length of 7.0±4.55mm invivo. Vessel diameters in angiographic evaluation were 2.44±0.21mm for the common carotid artery and 2.1±0.16mm for the maxillary artery. CONCLUSIONS: The novel small animal model for mechanical thrombectomy in rabbit is technically feasible and cheap. It offers comparable vessel diameters to cranial arteries and closely mimics human coagulation system.

Why are aneurysms of the posterior inferior cerebellar artery so unique? Clinical experience and review of the literature.

BACKGROUND: Aneurysms of the posterior inferior cerebellar artery (PICA) are rare lesions. The anatomical behaviour of the artery itself is complex and characterised by a multitude of variations. The same holds true for the aneurysms discovered there. Dissecting aneurysms can be found from the PICA origin to the distal artery berry. They have a wider range of clinical and radiographical presentations and their surgical treatment requires more than one standard approach. METHODS: We encountered 14 patients with PICA aneurysms within two surgical series of a total of 1345 cerebral aneurysm patients (1 %). In this patient group of the last 27 years only 3 of the 14 were distal aneurysms ("true" PICA aneurysms) RESULTS: The 14 patients harboured 15 aneurysms (9 right-sided and 6 left-sided). The female/male ratio of the patients was 9/5, the mean age 52.7 years. 13 of them had sustained an SAH. 7/14 patients were hypertensive, in 10 patients at least one of putative cerebrovascular risk factors was found. From the 15 aneurysms treated, 11 were typical berry aneurysms, 4 dissecting aneurysms. The aneurysms ranged in size from 5 to 20 mm (mean 9.1). 11 aneurysms were located within the anterior medullary segment, 1 in the tonsillomedullary and 2 in the telovelomedullary segments. All patients were surgically treated, 10 in a semi-sitting position via a suboccipital craniotomy, 4 in the prone position. 13 aneurysms were clipped, two were treated differently. Two patients died due to their bad preoperative clinical status. CONCLUSIONS: The clinical, radiographical and surgical approaches to PICA aneurysms still represent a challenge.

Frameless neuronavigation using the ISG-system in practice: from craniotomy to delineation of lesion.

The overall performance of a "pointer" neuronavigation system (the ISG ALLEGRO Viewing Wand) in everyday surgical use was evaluated by investigating the practical utility of the technical set-up for one particular surgical task. The basis of the analysis was the numerical evaluation of four areas of fundamental importance for most brain surgery: site and size of craniotomy, localisation of lesion, the trajectory through the brain, and the delineation of the lesion. In a protocol of 65 patients we based our examination on a subjective 4-point rating scale ranging from 0 (= no help) to 3 (= very helpful) for each of the four above categories. We investigated the potential influence of three factors: the lesions histology (4 groups), its size (3 categories) and the depth from the cortical surface (3 levels). Our experience is that the histology of the lesions has significant influence on the relative usefulness of neuronavigation for craniotomy (P < 0.017) and for delineation of the lesion (P < 0.003). We found neuronavigation most helpful for removing gliomas. Second, this system was found to be very helpful in locating small, hitherto hard-to-find, lesions (P < 0.01). Lesion's depth had no effect on the ratings (P > 0.2). Overall, the use of this system led to more precise skin incisions, better site and size of craniotomies tailored to the pathology, the trajectory through the brain, and to more precise delineation of the lesion.

Characterization of risk factor differences in perimesencephalic subarachnoid hemorrhage.

OBJECTIVE: The non-aneurysmal perimesencephalic subarachnoid hemorrhage (p-SAH) has a favorable outcome. Our objective was to provide a reason for that assessing the association of putative risk factors with this different type of hemorrhage in comparison to the aneurysmal subarachnoid hemorrhage (a-SAH). METHODS: We selected 185 consecutive cases of subarachnoid hemorrhage between September 1994 and August 1998 in a hospital-based case-control study and investigated the influence of hypertension, body weight, smoking and the three interacting blood factors hematocrit, fibrinogen and leukocrit. RESULTS: 1) Risk factors for SAH: For the entire study group an association of hypertension with the incidence of SAH was found both in the univariate analysis of this variable alone (P=0.001) and in the multivariate logistic regression (P=0.0001), aside from the risk factors smoking (P=0.0047) and hematocrit (P=0.0001). As to the risk of hypertensive subjects to experience SAH for different reasons, the logistic regression yielded an odds ratio (OR) of 3.54 [CI (95 %): 2.21-5.56]. 2) Risk factors for p-SAH: Patients with p-SAH differ in their risk profile from typical aneurysmal SAH cases with respect to their blood pressure status (P=0.019) and the investigated hemorheological parameters. CONCLUSIONS: A different association between possible risk factors and the two types of subarachnoid hemorrhages was ascertained. In general there seem to be fewer putative risk factors in the perimesencephalic SAH cases compared to the typical aneurysmal hemorrhages.

Is blood pressure really a trigger for the circadian rhythm of subarachnoid hemorrhage?

BACKGROUND AND PURPOSE: Circadian blood pressure changes are not infrequently cited as a trigger for the onset of subarachnoid hemorrhage (SAH). Our purpose was to determine the reliability of this chronorisk and study the variability and consequences of it as it occurs in hypertensive and normotensive individuals. METHODS: Of 273 consecutive patients with proven SAH of aneurysmal origin seen between January 1990 and December 1993, we studied 120 (44%) for whom the exact time of hemorrhage could be reliably determined. Beyond the recognition of a circadian rhythm for this collective, the patients were then sorted by blood pressure, yielding one group each of 80 normotensive (group N, 66.7%) and hypertensive (group H, 33.3%) individuals. The differential chronorisk of these two groups was studied. RESULTS: A circadian rhythm with a definitive characteristic acrophase was observed for the entire group, occurring between 9 AM and 10 AM (chi 2 test, P < .0005) with a possible secondary peak in the afternoon hours. The separation into two blood pressure groups somewhat surprisingly revealed a different curve for each group (chi 2 test, P = .01). Statistical analysis of each group's separate chronorisk revealed that this acrophase only holds true for hypertensive individuals, whereas normotensive patients not only lack a morning peak, but an apparent elevation in the afternoon is statistically irrelevant, leading to the impression that SAH in normotensive persons seems to be subject to no circadian rhythm at all. CONCLUSIONS: The incidence of SAH conforms to circadian blood pressure variation in hypertensive patients, similar to the diurnal rhythms observed with strokes and myocardial infarctions. This leads to the hypothesis that blood pressure elevation is a trigger for the onset of bleeding in this group. In clear contrast, normotensive individuals with cerebrovascular aneurysms seem to have a random 24-hour distribution of SAH onset times, thus leaving the nature of a possible trigger mechanism unresolved.

Percutaneous endoscopic lumbar discectomy: minimally invasive, but perhaps only minimally useful?

BACKGROUND A few recent studies dampen the euphoric reports of the value of percutaneous endoscopic lumbar discectomy (PELD) in the treatment of discogenic disease. We felt that a large-scale comparison between PELD and the still minimally invasive open lumbar disk surgery (OLDS) was called for. METHODS This report is based on the surgical experience of one year (1991) and is confined to the intervertebral disk level L4-5. Three hundred thirteen patients treated by open disk surgery were compared with 13 who were selected for percutaneous discectomy. RESULTS Using careful selection criteria, only 13 (4%) of a possible 326 were considered potentially suitable for PELD. Of these, only eight were wholly suitable and were operated on percutaneously. Within the first postoperative month, 62.5% (5 patients) of the PELD group required open surgery for definitive treatment, whereas only 14 (4%) of the 313 OLDS patients had to undergo additional surgery. CONCLUSIONS Although it may of benefit to a very few, we feel that the PELD method cannot be considered a substitute for, or even an alternative to, traditional surgery in most cases.

Another case of acoustic schwannoma and epidermoid cyst occurring as a single cerebellopontine angle mass: possibly not so rare?

This is the second case of adjacent occurrence of an acoustic schwannoma and epidermoid cyst in the cerebellopontine angle. This case of a 70-year-old woman is presented with a history of her illness, neuroradiologic data, and photographs during the operation. We compare this case with the first of its kind.

[Immunoscintigraphy for the detection of inflammation foci in bone and joint diseases]. / Immunszintigraphie zur Aufdeckung von Entzündungsherden bei Knochen- und Gelenkserkrankungen.

We evaluated the monoclonal antibody MAb, BW 250/183, which is easy to label with Tc-99m, with respect to its clinical application for the detection of inflammatory processes in bone and joint diseases. This monoclonal antibody is a murine immunoglobulin (IgG1 isotype), directed against NCA 95 (nonspecific cross-reacting antigen), which is also present on the surface of neutrophil granulocytes. We investigated patients with acute (n = 9) and chronic (n = 3) osteomyelitis, with coxitis (n = 3) and coxarthrosis (n = 2), with septic hip prosthesis (n = 8) and loosening hip prosthesis (n = 14), with low back pain (n = 4), with spondylitis (n = 5) and with postoperative spondylodiscitis (n = 9). With reference to the total number of patients examined in this study we found 29 true positive results, 22 true negative results, 4 false negative results and 2 false positive results. This gives a sensitivity of 88% and a specificity of 92%. The lesions were already visualized within 4 to 6 hours, but 24 hour pictures are desirable. SPECT pictures are mandatory in patients with diseases of the hip or of the spine because sensitivity is considerably improved thereby.

Invasion of the cavernous sinus by medial sphenoid meningioma--"radical" surgery and recurrence.

We have reviewed the cases of 57 patients with medial sphenoid meningioma who were operated on in our department during the period 1976 to 1988. The patients were grouped according to location, and their pertinent clinical features are presented. Given the frequency of invasion of the cavernous sinus by such tumours, the following question must be considered in each individual case: the potential benefit of the most radical surgery possible, to minimize the recurrence rate, must be weighed against the cost to the patient in diminished quality of life of iatrogenic neurological impairment. We currently advocate the following strategy: radical removal of tumour tissue lying within the cavernous sinus is unwarranted for the first operation if it would entail iatrogenic neurological damage. Only if subsequent follow-up reveals either fast growth of this tissue, or neurological signs and symptoms attributable to it, do we then attempt uncompromising radicality at a second operation.