Flanagan, E P

Background: Tremor in multiple sclerosis (MS) is often refractory to medications. Deep brain stimulation (DBS) may help, but possible side effects and disease exacerbation limit its use. Objectives: Evaluate outcomes of DBS for MS-associated tremor. Methods: Retrospective review of 18 patients with MS-associated tremor who underwent DBS, analyzing Expanded Disability Status Scale (EDSS) and Fahn–Tolosa–Marin (FTM) tremor scores. Results: Median age at surgery was 49.5 years (range, 28–75), with postoperative follow-up 2.5 years (range, 0–22). No relapses (0/18) or new lesions (0/8) occurred postoperatively. All had ventral intermediate nucleus leads; other targets were not used in programming. EDSS remained stable (median 6 to 6.25; p = 0.2). FTM scores improved (median 14.5 to 10, p = 0.008). Patients with EDSS 3.5–6 had variable outcomes ( p = 0.02). Conclusions: DBS is a potential treatment for severe MS tremor and did not provoke relapse. Targeting VIM alone may optimize tremor control and maintain magnetic resonance imaging (MRI) access.

Abstract Objectives γ‐Aminobutyric acid B receptor (GABA B R)‐IgG (immunoglobulin G) is an intermediate‐risk paraneoplastic autoantibody often associated with seizures. We aimed to assess the clinical and oncological features of GABA B R‐IgG autoimmune encephalitis (AE) and evaluate the performance of antibody testing. Methods Patients testing positive for GABA B R‐IgG in serum/cerebrospinal fluid (CSF) at Mayo Clinic Neuroimmunology Laboratory were identified. Archived sera were retested by cell‐based assay (CBA) at 1:100 and 1:200 dilutions. A live‐cell flow cytometry–based assay (LCFBA) was developed and validated using archived sera and CSF. True positivity included patients with classic presentations of GABA B R‐IgG AE or oncological explanations for antibody presence. Results Eighty‐six patients (median age 63 years; 43 female) presented with classic presentations of GABA B R‐IgG AE: encephalopathy with prominent seizures ( n = 55), status epilepticus ( n = 23), and rapidly progressive dementia ( n = 8). In addition, 44 patients (33%) had a false‐positive result for GABA B R‐IgG characterized by non‐specific symptoms/alternate diagnoses. Malignancy was identified in 78% of true‐positive patients, predominantly small cell lung carcinoma (SCLC). Testing serum at 1:100 dilution on CBA and using tissue immunofluorescence assay (IFA) in serum and CSF improved the identification of true‐positive patients ( p < 0.001). CBA at 1:100 dilution performed better than conventional CBA (at 1:10 dilution, p < 0.001) and tissue IFA ( p = 0.031). An in‐house LCFBA showed 100% sensitivity and specificity in CSF, performing similarly to conventional CBA ( p = 0.125) in CSF, but better than tissue IFA ( p = 0.031). Furthermore, serum LCFBA performed better than conventional CBA ( p = 0.022) and tissue IFA ( p = 0.006). LCFBA had the highest diagnostic accuracy and was closely followed by CBA at 1:100 dilution. Significance GABA B R‐IgG AE often presents as encephalopathy with seizures or status epilepticus in the context of an underlying SCLC. Multimodal evaluation using tissue IFA and fixed CBA at higher dilutions improves detection of true cases. LCFBA performs very well as a diagnostic test with very high sensitivity and specificity.