Controversies and Clinical Applications of Non-Invasive Transspinal Magnetic Stimulation: A Critical Review and Exploratory Trial in Hereditary Spastic Paraplegia.

Magnetic stimulation is a safe, non-invasive diagnostic tool and promising treatment strategy for neurological and psychiatric disorders. Although most studies address transcranial magnetic stimulation, transspinal magnetic stimulation (TsMS) has received recent attention since trials involving invasive spinal cord stimulation showed encouraging results for pain, spasticity, and Parkinson's disease. While the effects of TsMS on spinal roots is well understood, its mechanism of action on the spinal cord is still controversial. Despite unclear mechanisms of action, clinical benefits of TsMS have been reported, including improvements in scales of spasticity, hyperreflexia, and bladder and bowel symptoms, and even supraspinal gait disorders such as freezing and camptocormia. In the present study, a critical review on the application of TsMS in neurology was conducted, along with an exploratory trial involving TsMS in three patients with hereditary spastic paraplegia. The goal was to understand the mechanism of action of TsMS through H-reflex measurement at the unstimulated lumbosacral level. Although limited by studies with a small sample size and a low to moderate effect size, TsMS is safe and tolerable and presents consistent clinical and neurophysiological benefits that support its use in clinical practice.

Electroretinography reveals retinal dysfunction in Parkinson's disease despite normal high-resolution optical coherence tomography findings.

INTRODUCTION: Parkinson's disease (PD)-associated inner retinal abnormalities, particularly the retinal ganglion cells (RGC) layer, on optical coherence tomography (OCT) have recently gained importance as a biomarker of non-motor involvement of the disease but functional RGC evaluation using photopic negative response (PhNR) has not yet been determined. This study aims to compare structural and functional findings of the retina and optic nerve in PD with healthy controls (CT) including PhNR and OCT. METHODS: Forty-one eyes of 21 PD patients and 38 eyes of 19 CT underwent ophthalmic examination including visual contrast sensitivity test (CS), OCT, light-adapted full-field electroretinography (ffERG), and PhNR. OCT was used to measure the peripapillary retinal nerve fiber layer, the segmented macular layers, and the choroid. For functional parameters, CS, ffERG (oscillatory potentials, photopic response, 30 Hz-flicker), and PhNR waves were used. Measurements were compared using generalized estimating equation and significance was set at P ≤ 0.05. RESULTS: The PD group presented a significantly lower mono- and binocular CS, oscillatory potentials amplitude, b-wave amplitude on ffERG (152.3[45.4] vs 187.1[32.7]µV; P = 0.002), and PhNR amplitude (135.0[35.0] vs 156.3[34.1]µV; P = 0.025). There was no statistically significant difference in OCT measurements between groups. No correlation was found between statistically significant measurements and clinical data. CONCLUSIONS: Functional abnormalities on CS, ffERG, and PhNR can be detected in PD even when structural damages are not observed on OCT. PhNR represents a new potential biomarker in PD. Our findings indicate dysfunction of bipolar, amacrine, and retinal ganglion cells in PD, probably with a cellular dysfunction overcoming morphological damage.

Safety and Outcomes of Dentate Nucleus Deep Brain Stimulation for Cerebellar Ataxia.

Cerebellar symptoms remain orphan of treatment options despite being prevalent and incapacitating. Investigate whether dentate nucleus deep brain stimulation (DN DBS) is safe and leads to improvements in cerebellar symptoms when compared to sham stimulation. This randomized double-blind crossover pilot trial enrolled five patients with spinocerebellar ataxia type 3 or post-lesion ataxia. Active or sham phases were randomly performed three months apart. The primary outcome was ataxia improvement as measured by the Scale for the Assessment and Rating of Ataxia (SARA) after the active compared to the sham period. Secondary outcome measures included safety and tolerability, the Fahn-Tolosa-Marin Tremor Rating Scale (FTMRS), quality of life measurements, and patients' global impression of change. The effects on ataxia were numerically better in four out of five patients after active versus sham stimulation. The composite SARA score did not change after comparing active to sham stimulation (8.6 ± 3.6 versus 10.1 ± 4.1; p = 0.223). The FTMRS showed significant improvement after active stimulation versus sham (18.0 ± 17.2 versus 22.2 ± 19.5; p = 0.039) as did patients' global impression of change (p = 0.038). The quality of life was not modified by stimulation (p = 0.337). DN DBS was well tolerated without serious adverse events. One patient had the electrode repositioned. DN DBS is a safe and well tolerated procedure that is effective in alleviating cerebellar tremor. In this small cohort of ataxic patients, DN DBS did not achieve statistical significance for ataxia improvement.

Behavioral manifestations in a Brazilian non-demented C9orf72-negative ALS population.

Cognitive decline and behavioral changes are common features in amyotrophic lateral sclerosis (ALS) and imply worse prognosis as well as increased disease burden for patients and caregivers. Currently, there is a lack of studies regarding behavioral profile in Brazilian ALS cohorts. We assessed the prevalence and profile of behavioral impairment (ALSbi) in a Brazilian non-demented C9orf72-negative ALS cohort according to broad behavioral assessment and the latest consensus. Among 76 initially recruited consecutive ALS patients, 70 were included, including seven ALS type 8 (VAPB-related ALS) individuals. Patients with Frontotemporal Dementia (FTD) diagnosis were excluded. Sixteen ALS patients (23%) were diagnosed as ALSbi. Among ALS type 8 individuals, 2 (28.6%) were diagnosed as ALSbi. Neuropsychiatric Inventory Questionnaire (NPI) total scores did positively correlate with age, but not with other demographic or clinical data. Apathy was the most prevalent finding in the ALSbi subgroup, although the prevalence (20%) was smaller than reported in previous literature. Dysphoria and anxiety were also prevalent findings in the whole ALS cohort. Future studies with larger cohorts and validated ALS-specific tools are needed in order to expand our knowledge.