Does Head Tremor Predict Postural Instability After Bilateral Thalamic Stimulation in Essential Tremor?

Essential tremor (ET) may present with head tremor (HT), of presumed cerebellar nature. Deep brain stimulation (DBS) targeting the ventral intermediate (Vim) nucleus of the thalamus is a highly effective therapy for medication-refractory ET. However, stimulation-related side effects may include cerebellar abnormalities, such as postural instability. This retrospective cohort study evaluated the risk of post-Vim DBS postural instability (primary outcome measure) in patients with versus without head tremor (HT vs. nHT). The primary outcome measure, namely post-DBS postural instability, was assessed in both groups using a Wilcoxon rank sum t-test. The time to postural instability was determined using Cox proportional hazards regression analysis adjusted for age and sex. Out of 30 patients analyzed during the follow up period, there was similar postural instability detected in HT (9/14, 64%) and nHT patients (11/16, 69%) at 24 months post-Vim DBS (p=0.82), adjusted hazard ratio[aHR]=0.82, p=0.69). These data suggest that the presence or absence of HT does not have an impact on postural instability after bilateral Vim DBS in patients with ET.

Use of a frameless computed tomography-guided stereotactic biopsy system for nasal biopsy in five dogs.

CASE DESCRIPTION: 5 dogs (median age, 9 years; median body weight, 31 kg [68.2 lb]) with undefined nasal masses were examined after undergoing CT of the head and nasal biopsy via a rostral rhinoscopic or unaided (blind) approach because histologic results for collected biopsy specimens (inflammatory, necrotic, or hemorrhagic disease) suggested the specimens were nonrepresentative of the underlying disease process identified via CT (aggressive or malignant disease). CLINICAL FINDINGS: Clinical signs at the time dogs were evaluated included open-mouth breathing, sneezing, or unilateral epistaxis. Histologic findings pertaining to the original biopsy specimens were suggestive of benign processes such as inflammation. In an attempt to obtain better representative specimens, a frameless CT-guided stereotactic biopsy system (CTSBS) was used to collect additional biopsy specimens from masses within the nasal and sinus passages of the dogs. The second set of biopsy specimens was histologically evaluated. TREATMENT AND OUTCOME: Histologic evaluation of biopsy specimens collected via the CTSBS revealed results suggestive of malignant neoplasia (specifically, chondrosarcoma, hemangiopericytoma, or undifferentiated sarcoma) for 3 dogs, mild mixed-cell inflammation for 1 dog, and hamartoma for 1 dog. No complications were reported. These findings resulted in a change in treatment recommendations for 3 dogs and confirmed that no additional treatment was required for 1 dog (with hamartoma). For the remaining dog, in which CT findings and clinical history were strongly suggestive of neoplasia, the final diagnosis was rhinitis. CLINICAL RELEVANCE: Biopsy specimens were safely collected from masses within the nasal and sinus passages of dogs by use of a frameless CTSBS, allowing a definitive diagnosis that was unachievable with other biopsy approaches.