Sukhraaj Basati, Bhargav Desai, Ali Alaraj, Fady Charbel and Andreas Linninger
Experimental data about the evolution of intracranial volume and pressure in cases of hydrocephalus are limited due to the lack of available monitoring techniques. In this study, the authors validate intracranial CSF volume measurements within the lateral ventricle, while simultaneously using impedance sensors and pressure transducers in hydrocephalic animals.
A volume sensor was fabricated and connected to a catheter that was used as a shunt to withdraw CSF. In vitro bench-top calibration experiments were created to provide data for the animal experiments and to validate the sensors. To validate the measurement technique in a physiological system, hydrocephalus was induced in weanling rats by kaolin injection into the cisterna magna. At 28 days after induction, the sensor was implanted into the lateral ventricles. After sealing the skull using dental cement, an acute CSF drainage/infusion protocol consisting of 4 sequential phases was performed with a pump. Implant location was confirmed via radiography using intraventricular iohexol contrast administration.
Controlled CSF shunting in vivo with hydrocephalic rats resulted in precise and accurate sensor measurements (r = 0.98). Shunting resulted in a 17.3% maximum measurement error between measured volume and actual volume as assessed by a Bland-Altman plot. A secondary outcome confirmed that both ventricular volume and intracranial pressure decreased during CSF shunting and increased during infusion. Ventricular enlargement consistent with successful hydrocephalus induction was confirmed using imaging, as well as postmortem. These results indicate that volume monitoring is feasible for clinical cases of hydrocephalus.
This work marks a departure from traditional shunting systems currently used to treat hydrocephalus. The overall clinical application is to provide alternative monitoring and treatment options for patients. Future work includes development and testing of a chronic (long-term) volume monitoring system.
Victor A. Aletich, Gerard M. Debrun, Mukesh Misra, Fady Charbel and James I. Ausman
Object. Reports in the literature have offered discussions of the feasibility, efficacy, and safety of balloon-assisted Guglielmi detachable coil (GDC) placement in wide-necked intracranial aneurysms, which was first described by Jacques Moret as the “remodeling technique.” In this article the authors summarize their results in a subset of aneurysms treated with GDCs using the remodeling technique.
Methods. This report contains a retrospective analysis of 72 patients with 75 aneurysms who underwent 79 endovascular procedures performed using the remodeling technique. Morphological outcome was determined at the end of each procedure and by reviewing available follow-up angiograms. Clinical assessments and outcomes are reported using a modified Glasgow Outcome Scale.
Coils were placed in 66 (88%) of 75 aneurysms selected for treatment. In eight aneurysms (11%) treatment failures occurred due to the tortuosity of the vessel used to reach the aneurysms or because of balloon inadequacies.
Incorporating all available follow-up data the authors found that 50 (78%) of 64 aneurysms were completely or subtotally (> 95%) occluded and eight (12%) of 64 were incompletely (< 95%) occluded. Since the time of coil placement, eight aneurysms have progressed to complete occlusion and another five have exhibited progressive thrombosis on follow-up angiograms. In three aneurysms there has been neck remnant growth. Surgical clipping was performed to treat six aneurysms after an initial coil placement procedure. Permanent incidences of morbidity were limited to four patients and there were three deaths directly related to the procedure.
Conclusions. The remodeling technique shows promise in increasing the number of cerebral aneurysms amenable to treatment by endovascular coil placement, and offers an alternative approach to aneurysms that have met with failed surgical treatment or are surgically inaccessible. Long-term follow-up review is needed to determine the final outcome of aneurysms treated by this technique.