Peripheral Nerve Disorder

A multicenter, 30 patient prospective single arm evaluation of the Nervonik system in symptomatic patients with chronic severe knee, elbow or shoulder pain. COHORT 1: The initial cohort of patients will receive the Nervonik neurostimulator for up to 8 hours. The patient will remain local to the care facility for implant stimulator program changes until the patient is satisfied with the degree of pain relief. The implant will be removed from the patient at the end of the evaluation. COHORT 2: The second cohort of patients will include those patients from cohort 1 who have determined the Nervonik implant provides suitable pain relief and agree to have a permanent implant placed. In addition, the second cohort includes non-cohort one patients meeting the trial requirements and agreeing to participate in the trial.

Neuromuscular ultrasound (NMUS) is emerging as a valuable non-invasive diagnostic tool. In GBS, NMUS can detect proximal nerve enlargement early, before neurophysiological changes. Persistent nerve enlargement can be observed up to 15 years, though its correlation with disability varies. Research is needed to clarify NMUS findings in GBS and CIDP over time. Early detection of nerve root enlargement via NMUS could facilitate earlier diagnosis and intervention, improving patient outcomes and understanding of these conditions\' pathophysiology. This study aims to determine if nerve alterations in acute GBS and CIDP detectable by ultrasound match electrodiagnostic findings and if this method aids early diagnosis. The investigators will perform serial nerve ultrasounds and NCS to investigate nerve morphology, predict outcomes, and differentiate between axonal and demyelinating subtypes.