Evidence for the role of the dorsal ventral lateral posterior thalamic nucleus connectivity in deep brain stimulation for Gilles de la Tourette syndrome

Gilles de la Tourette syndrome (GTS) can manifest as debilitating, medically-refractory tics for which deep brain stimulation (DBS) of the centromedian-parafascicular complex (CM) can provide effective treatment. However, patients have reported benefit with activation of contacts dorsal to the CM and likely in the ventro-lateral thalamus (VL). At our institution, a case of a robust and durable response in a GTS patient required stimulation in the CM and more dorsally. We explore the structural connectivity of thalamic subregions associated with GTS using diffusion MRI tractography. Diffusion weighted images from 40 healthy Human Connectome Project (HCP) subjects and our GTS patient were analyzed. The VL posterior nucleus (VLp) and the CM were used as seeds for whole-brain probabilistic tractography. Leads were localized via linear registration of pre-/post-operative imaging and cross-referenced with the DBS Intrinsic Template Atlas. Tractography revealed high streamline probability from the CM and VLp to the superior frontal gyrus, rostral middle frontal gyrus, brainstem, and ventral diencephalon. Given reported variable responses to DBS along the thalamus, we segmented the VLp based on its connectivity profile. Ventral and dorsal subdivisions emerged, with streamline probability patterns differing between the dorsal VLp and CM. The CM, the most reported DBS target for GTS, and the dorsal VLp have different but seemingly complimentary connectivity profiles as evidenced by our patient who, at 1-year post-operatively, had significant therapeutic benefit. Stimulation of both regions may better target reward and motor circuits, resulting in enhanced symptom control for GTS.

Stereotactic laser ablation of the splenium for intractable epilepsy

Partial or complete corpus callosotomies have been applied, traditionally via open surgical or radiosurgical approaches, for the treatment of epilepsy in patients with multifocal tonic, atonic, or myoclonic seizures. Minimally invasive methods, such as MRI-guided laser interstitial thermal ablation (MTLA), are being employed to functionally remove or ablate seizure foci in the treatment of epilepsy. This therapy can achieve effectiveness similar to that of traditional resection, but with reduced morbidity compared with open surgery. Here, we present a patient with a history of prior partial corpus callosotomy who continued to suffer from medically refractory epilepsy with bisynchronous onset. We report on the utilization of laser ablation of the splenium in this patient to achieve full corpus callosotomy. Adequate ablation of the splenial remnant was confirmed by postoperative MRI imaging, and at four-month follow-up, the patient's seizure frequency had dropped more than 50%. This is the first reported instance of laser ablation of the splenium to achieve full corpus callosotomy following a previous unsuccessful anterior callosotomy in a patient with intractable generalized epilepsy.

Biocompatibility of polyhydroxyalkanoate as a potential material for ligament and tendon scaffold material

There is a strong need for new biodegradable materials that are suitable for scaffolds in tissue engineering of tendons and ligaments. In many cases, quick degradation rates are favorable, however, with respect to ligament and tendon replacement, slowly degrading polymers are clearly favored. Prime candidates are members of the large class of polyhydroxyalkanoates (PHAs), which are thermoplastic/elastomeric biopolyesters that are slowly degraded by surface erosion. Moreover, their physico-mechanical properties can be tailored during biosynthesis in bacteria or by chemical modifications. They may be spun into fibers, coated on surfaces or be part of composites. This study has investigated the biocompatability of seven different thermoplastic or elastomeric PHAs using L929 murine fibroblast cells. Cell viability and proliferation over 7 days was analyzed with live/dead staining and a picogreen assay. In addition, extracellular matrix production was measured with the hydroxyproline assay after 14 days. It was found that cell attachment to the PHA film ranged from 85-99% after 7 days. Three PHA films (PHBV (92/8), PHOUE-POSS and PHUE-O3) supported similar cell viability in comparison to the controls performed on tissue culture plastic (polystyrene), whereas the biomaterials (PHUA, PHUE, PHB and PHOUE) showed fewer viable cells than in controls. PHB, PHUE-O3, and PHBV with a water contact angle below 85 degrees supported a similar amount of collagen production in comparison to the tissue culture plastic controls. PHUA, PHUE, PHOUE, and PHOUE-POSS showed a decrease in collagen production in comparison to the controls after 14 days. Overall, PHB, PHBV, and PHUE-O3 demonstrated good performance with regards to potential use as a tissue-engineering scaffold.