Notalgia paresthetica following neuralgic amyotrophy: a case report

Serratus muscle stimulation effectively treats notalgia paresthetica caused by long thoracic nerve dysfunction: a case series

Currently, notalgia paresthetica (NP) is a poorly-understood condition diagnosed on the basis of pruritus, pain, or both, in the area medial to the scapula and lateral to the thoracic spine. It has been proposed that NP is caused by degenerative changes to the T2-T6 vertebrae, genetic disposition, or nerve entrapment of the posterior rami of spinal nerves arising at T2-T6. Despite considerable research, the etiology of NP remains unclear, and a multitude of different treatment modalities have correspondingly met with varying degrees of success. Here we demonstrate that NP can be caused by long thoracic nerve injury leading to serratus anterior dysfunction, and that electrical muscle stimulation (EMS) of the serratus anterior can successfully and conservatively treat NP. In four cases of NP with known injury to the long thoracic nerve we performed transcutaneous EMS to the serratus anterior in an area far lateral to the site of pain and pruritus, resulting in significant and rapid pain relief. These findings are the first to identify long thoracic nerve injury as a cause for notalgia paresthetica and electrical muscle stimulation of the serratus anterior as a possible treatment, and we discuss the implications of these findings on better diagnosing and treating notalgia paresthetica.

TMS Neuro-Cardiovascular Coupling in Vascular Compression Cranial Neuropathy

Background:

Neurovascular compression (NVC) may cause cranial mononeuropathy but lacks a definitive diagnostic investigation. We hypothesized that the arterial pressure wave (APW) would interact at the neurovascular interface in NVC to inhibit transmission of transcranial magnetic stimulation (TMS) stimuli to affected muscles.

Methods:

We report a novel neurophysiological method coupling cardiovascular physiology with TMS. The electrocardiogram (ECG) and arterial pressure wave (APW) were coupled to triggering of cortical TMS in a patient with NVC-induced spinal accessory (CNXI) mononeuropathy. Outcome measures included motor evoked potential (MEP) amplitudes and firing probabilities of normal and affected trapezieus (TPZ). Values at intervals in proximity to the APW (40/80/120/160ms) were compared to baseline (800ms) using ANOVA and student t-test.

Results:

Electrocardiogram triggered TMS of CNXI pathways with 100% reliability. MEP amplitudes were decreased in proximity to the APW, particularly at 120ms (0.21±0.04 mV versus 0.39±0.10mV, p=0.003). TPZ firing probabilities were similarly inhibited (43.8% versus 88.2%, p=0.009). No effect of APW proximity was observed on the unaffected side (p=0.868). Procedures were well tolerated.

Conclusions:

Vascular compression causes CNXI mononeuropathy. Transcranial magnetic stimulation-cardiovascular coupling may evaluate neurovascular junction interactions and non-invasively diagnose NVC.