2023 Workshop Handout Bundle-EDX and US Evaluation of the Lower Cranial Nerves

EDX and US Evaluation of the Lower Cranial Nerves

Pdf Summary

The AANEM workshop titled "Electrodiagnostic & Ultrasound Evaluation of the Lower Cranial Nerves" led by Dr. Hani Kushlaf and Dr. Long Davalos Loo focuses on the electrodiagnostic (EDX) and ultrasound evaluation of cranial nerves XI (spinal accessory) and XII (hypoglossal). The workshop aims to equip attendees with a systematic approach to evaluate these nerves, emphasizing electrode placement, site stimulation, needle insertion, and the interpretation of findings.<br /><br />Anatomically, CN XI features both cranial and spinal components and innervates muscles like the sternocleidomastoid and upper trapezius. CN XII originates from the nuclei in the medulla oblongata, forming the nerve that innervates the genioglossus muscle. The common causes of mononeuropathies in these nerves include surgical trauma, tumors, and, for CN XII, carotid endarterectomy.<br /><br />Clinically, CN XI injuries manifest with symptoms like a drooped shoulder and limited arm abduction, often seen post radical neck dissection. Differential diagnoses for CN XI involve conditions such as brachial plexopathy and cervical radiculopathy. CN XII injury symptoms include dysarthria, dysphagia, and tongue atrophy, with potential differentials including ALS and myasthenia gravis.<br /><br />EDX can be significantly helpful in diagnosing and managing neuromuscular conditions like myasthenia gravis and ALS. For CN XI, the workshop specifies a nerve conduction study (NCS) protocol where the nerve is electrically stimulated near the sternocleidomastoid muscle, followed by repetitive nerve stimulation (RNS) techniques. While NCS isn't typically performed on CN XII, needle electromyography (EMG) of muscles innervated by CNs XI and XII, like the upper trapezius and genioglossus, is valuable for diagnosing conditions like ALS. The workshop also highlights ultrasound methods to visualize the spinal accessory nerve, which is small and requires a high-frequency probe.<br /><br />Finally, the document discusses technical considerations and abnormal findings in NCS and EMG studies, emphasizing careful side-to-side comparisons, muscle activation, and proper electrode placement to yield accurate diagnoses and guide clinical decisions.

Keywords

Electrodiagnostic

Ultrasound

nmus

sono

Cranial Nerves

Spinal Accessory

Hypoglossal

Electrode Placement

Nerve Conduction Study

ncs

ncv

Needle Electromyography

Mononeuropathies

Neuromuscular Conditions

nerve conduction studies

nerve conduction study

ncs

ncv

ultrasound

nmus

sono

ultrasound