Resection of calcified aortic heart leaflets in vitro by Q-switched 2 µm microsecond laser radiation.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) can result in paravalvular leakage and stent deformation in the presence of severe calcification. This study was undertaken to determine the efficacy of laser-assisted resection of calcific aortic valve leaflets as a method to minimize the effects of calcium on perivalvular leakage during TAVI. METHODS: A Q-switched Tm:YAG laser emitting at a wavelength of 2.01 µm was used to evaluate the cutting efficiency on highly calcified human aortic leaflets in vitro (N = 10). A pulse energy of 4.3 mJ, a pulse duration of 0.8-1 µs, and a repetition rate of 1 kHz were used. The radiation was transmitted via a 200 µm core diameter quartz fiber. Resection was performed in a fiber-tissue contact mode on water-covered samples in a dish. The remnant particles were analyzed with respect to quantity and size by light microscopy. RESULTS: A resection rate of 40.4 ± 22.2 mg/min on highly calcified aortic leaflets was achieved. This corresponds to a cutting speed of approximately 1 cm/min; a laser dissection time of 3 min per leaflet is expected. The majority of the remnant particles (85.4%) were <6 µm in diameter, with only 0.1% exceeding 300 µm. CONCLUSIONS: The Q-switched Tm:YAG laser system showed promising results in cutting calcified aortic valves, by transmitting sufficient energy through a small flexible fiber. Catheter-based removal of aortic valve calcification may help to improve TAVI technology.

Electrophysiological proof of diffusion-weighted imaging-derived depiction of the deep-seated pyramidal tract in human.

In the living human brain the pyramidal tract (PT) can be displayed with magnetic resonance diffusion-weighted imaging (DWI). Although this imaging technique is already being used for planning and performing neurosurgical procedures in the PT vicinity, there is a lack of verification of DWI accuracy in other areas outside the directly subcortical PT parts. Before definitive electrode placement into the subthalamic nucleus (STN) in patients with Parkinson disease (PD) for chronic stimulation, the stimulation effect on PD symptoms and the side-effects, namely PT activation at the level of the internal capsule (IC), are electrophysiologically tested. To analyze DWI accuracy by matching the stereotactic coordinates of the electrophysiologically proven IC position with these of the DWI-derived IC display, DWI was added to the routine MRI work-up in the stereotactic frame prior to functional surgery in 6 patients. In all of the 10 displayed fiber tracts, concordant findings for imaging and macrostimulation were made. The authors proved for the first time that DWI correctly depicts the deep seated, principle motor pathways in the living human brain. Due to methodical limitations of this study the accuracy of the proven IC display is limited to 3 mm which has proven to be sufficient for the planning and performance of neurosurgical procedures in the vicinity of large fiber tracts.

Lateral transmuscular or combined interlaminar/paraisthmic approach to lateral lumbar disc herniation? A comparative clinical series of 48 patients.

BACKGROUND: The optimum operative technique for lateral lumbar disc herniations (LLDH) remains unclear, and both interlaminar and extraspinal approaches are used. OBJECTIVE: To compare outcome after LLDH removal either by a lateral transmuscular approach (LTM) or by a combined interlaminar and paraisthmic approach (CIP). METHODS: 28 patients underwent surgery using CIP and 20 using LTM. All patients were operated on by the same neurosurgeon. The clinical presentation of the two groups was comparable. Overall outcome was assessed after a mean follow up period of between 19 and 37 months using the Ebeling classification. In addition, the effect of surgery on radicular pain, low back pain, and sensory and motor deficits was defined. RESULTS: Excellent to good results were achieved in 95% of the LTM group and 57% of the CIP group. The outcome was satisfactory to poor in 5% of the LTM and 43% of the CIP group (p<0.004). The percentage of sensorimotor deficit and of radicular pain improvement was higher in the LTM group. New low back pain was found exclusively in the CIP group (21%). The complication rate was 5% in the LTM group and 11% in the CIP group. CONCLUSIONS: The LTM approach achieves a better overall outcome and improvement in radiculopathy. The complication rate is lower with the transmuscular route and the risk of new low back pain is minimised. These results are likely to be attributable at least in part to the lesser invasiveness of the LTM approach.

Subthalamic nucleus stimulation for advanced Parkinson's disease: how to find a far medial STN.

In a patient with advanced Parkinson's disease, an anatomically deviant far medial subthalamic nucleus (STN) posed problems in the placement of DBS electrodes for chronic high frequency (HF) stimulation despite the use of multimodal targeting with 1) statistical atlas data, 2) T (2)-weighted (T (2)W) magnetic resonance imaging (MRI), 3) microelectrode recording, and 4) clinical testing with macro stimulation. Diagnostic T (2)W MRI suggested that the patient's STN was in a typical location and seemed to confirm the statistical atlas-based planning. Intraoperatively, cell activity recording (MER) with five parallel electrodes could not reveal any STN typical activity profile and electrical stimulation was not able to disclose a medial or lateral displacement of the electrodes. The operation was discontinued and postoperative stereotactic CT confirmed that the correct target area had been approached during the operation. Postoperative T (2)W MRI now disclosed a left STN which was 2 mm medial of the initial target and lead to a further medial target definition and finally to a successful DBS placement. In conclusion, finding a deep seated DBS target like the STN can be difficult in cases with an extremely deviant anatomy even if reiterative sophisticated multimodal planning is used. In the presented case we applied the integrated information from intraoperative MER, macrostimulation and postoperative imaging work-up and were able to complete DBS implantation successfully.

The role of intraoperative magnetic resonance imaging for the detection of hemorrhagic complications during surgery for intracerebral lesions an experimental approach.

BACKGROUND: Intraoperative magnetic resonance imaging (MRI) for guided biopsy or microsurgical resection of intracranial lesions is gaining broader acceptance. It is not known whether intraoperative MRI has the potential to detect hemorrhagic complications of these surgical procedures, because scientific research has so far focussed on the signal characteristics of less acute clots. It is the objective of this experimental study to investigate whether MRI can visualise intracerebral blood within minutes after its occurrence. METHODS: In 26 pigs, a frontal hematoma was produced by injecting autologous blood. Twenty pigs underwent MRI 30 minutes after injection, and 6 pigs within the first 10 minutes. MRI scans were performed on a 1.5T system. T1-weighted spin echo (SE), T2-weighted turbo spin echo (TSE), T2-weighted fluid attenuated inversion recovery (FLAIR), and T2-weighted gradient echo (GE) images were acquired. Depending on the differences of the signal intensities of the hematoma and the surrounding brain, the detectability of the hematoma was rated as good, fair, or poor. RESULTS: None of the induced hematomas were rated to be clearly visible on T1-weighted sequences. Six of the 26 hematomas (23%) were easily detectable on FLAIR sequences, 18 hematomas (69%) on T2-weighted TSE sequences, and 23 hematomas (88%) on the T2-weighted GE sequences. CONCLUSION: Extravasated blood can be identified with a high reliability within minutes after its occurrence on MRI provided that T2-weighted GE sequences are used for imaging. In conclusion, intraoperative MRI is not only of value for guidance of neurosurgical procedures, but also for immediate detection of hemorrhagic complications.

Experimental acute intracerebral hemorrhage. Value of MR sequences for a safe diagnosis at 1.5 and 0.5 T.

PURPOSE: To determine the detectability of intracerebral hematomas with MR imaging at 1.5 T and 0.5 T with fluid attenuated inversion recovery turbo spinecho (FLAIR) and gradient-echo sequences. MATERIAL AND METHODS: Twenty-seven intracerebral hematomas were created in 25 piglets by injection of venous blood into the brain through a burr hole. All were imaged with T2*-weighted gradient echo sequences (fast field echo, FFE), T2-weighted fluid attenuated inversion recovery turbo spin-echo sequences (FLAIR), T2-weighted turbo spin-echo (TSE) and T1-weighted spinecho sequences. Follow-up was performed on the 2nd, 4th and 10th postoperative days. Ten animals were additionally investigated with similar sequences at 0.5 T. Histologic correlation was obtained in all cases. RESULTS: T2* FFE sequences detected all acute intracerebral hematomas and demonstrated the size correctly at 1.5 T and 0.5 T. The conspicuity was better at 1.5 T. FLAIR sequences were unreliable in the hyperacute phase at 1.5 T: However. subarachnoid and intraventricular extension was best appreciated with FLAIR images. T2 TSE images were incapable of detecting paraventricular and subarachnoid hemorrhages, but clearly demonstrated intracerebral blood in other locations. TI-weighted images were insensitive to hemorrhage in the acute state but very useful in subacute and chronic hematomas. CONCLUSION: The safe and reliable diagnosis of intracerebral hemorrhage is probably possible with MR imaging at 1.5 T and 0.5 T even of hematomas less than 90 min old, but requires the application of at least FLAIR, T2* FFE and T1 sequences and is therefore time consuming.

Frameless stereotactically guided catheter placement and fibrinolytic therapy for spontaneous intracerebral hematomas: technical aspects and initial clinical results.

OBJECTIVE: Frame-based stereotactic puncture and catheter placement followed by fibrinolytic therapy and drainage is one treatment option in the management of spontaneous intracerebral hemorrhage (sICH). This minimally invasive procedure could even be simplified by frameless stereotaxy. The authors present their experiences with frameless stereotactic image-guided catheter placement for lysis and drainage of sICH, with emphasis on technical aspects. METHOD: In 27 patients with sICH, an infrared-based frameless stereotactic device was used for selecting trajectory and target point of hematoma drainage. A trajectory along the main axis of the hematoma was considered to be optimal for fibrinolytic therapy. An articulated arm served to maintain the predetermined trajectory during surgery and to guide catheter advancement. Clot lysis with recombinant tissue plasminogen activator (rt-PA) was initiated after radiological confirmation of correct catheter positioning. RESULTS: In all cases, selection of the optimal trajectory was not restricted by the frameless stereotactic device. In 25 of the 27 patients, the catheter was placed accurately along the predetermined trajectory into the target point. In two patients, the catheter was positioned at the lateral margin of the hematoma, excluding fibrinolytic therapy in one case. In 24 of 27 patients, the mean hematoma volume could be reduced from initially 52 ml to 17 ml in an average of two days. Hematoma enlargement following rt-PA injection was observed in two patients. Further complications were culture negative pleocytosis of cerebrospinal fluid in two and meningitis in one patient. CONCLUSION: Hematoma puncture and catheter placement for fibrinolytic therapy could be achieved with high accuracy and safety using frameless stereotaxy. This method allows unrestricted trajectory selection with catheter positioning along the main hematoma axis. Further studies are required to investigate if frameless stereotactic puncture and clot lysis could contribute to improve the outcome of patients with sICH.

Efficacy of clindamycin/primaquine versus trimethoprim/sulfamethoxazole in primary treatment of Pneumocystis carinii pneumonia.

Mild to moderately severe Pneumocystis carinii pneumonia in patients with AIDS was treated in a clinical trial with a combination regimen of primaquine and clindamycin, and the efficacy of this regimen was compared with that of the conventional treatment regimen of trimethoprim/sulfamethoxazole. The results revealed that primaquine/clindamycin appears to be an equally effective alternative to trimethoprim/sulfamethoxazole. The spectrum of side-effects was similar for the two regimens; side-effects occurred with equal frequency but appeared to be less severe in patients given primaquine/clindamycin. Because therapy with primaquine and clindamycin was limited to patients with mild to moderate Pneumocystis carinii pneumonia, studies with this regimen in more severe cases are warranted.

Family life among mainland Puerto Ricans in New York City slums.

PIP: Puerto Rican families who migrated to New York City in the 1950s are threatened by a system of impersonal relationships and norms which are at odds with their traditional values. Puerto Rican families have a tendency to have many children. A woman must have a child as soon as possible after marriage to show the community and her husband that she is fertile. They are forbidden by their husbands to use contraceptives, and most Puerto Rican men refuse to use contraceptives because of a machismo complex. Many of the women resort to sterilization. Common-law marriages are found frequently among the lower socioeconomic families. Mainland Puerto Rican families find problems trying to raise girls as virgins and boys with sexual freedom. The daughters want to adopt the dominant pattern of mainland society.^ieng