Trigeminal motor nerve conduction: deep temporal and mylohyoid nerves

Area of Science:

• Neurology
• Neurophysiology
• Clinical Electrophysiology

Background:

• The trigeminal nerve innervates facial muscles crucial for mastication and sensation.
• Accurate assessment of its motor branches, the deep temporal nerve (DTN) and mylohyoid nerve (MHN), is vital for diagnosing neurological disorders.
• Intraoral stimulation techniques offer a direct approach to evaluating these specific nerve pathways.

Purpose of the Study:

• To describe and evaluate the feasibility of intraoral nerve conduction studies for the DTN and MHN.
• To establish normative electrophysiological values for these nerves.
• To assess the clinical utility of these techniques in patients with trigeminal nerve dysfunction.

Main Methods:

• Nerve conduction studies were conducted on 42 subjects.
• Intraoral stimulation of the DTN and MHN was performed using a pediatric surface stimulator.
• Compound muscle action potentials were recorded from temporalis and mylohyoid muscles via surface electrodes.

Main Results:

• The mylohyoid nerve (MHN) response was consistently elicited bilaterally (upper latency limit 2.3 ms, mean amplitude 4.9 mV).
• The deep temporal nerve (DTN) response was elicited bilaterally in 60% of subjects (average latency 2.1 ms, average amplitude 4.3 mV).
• MHN responses were less technically demanding and more consistently obtained than DTN responses.

Conclusions:

• Intraoral nerve conduction studies for the DTN and MHN are feasible and provide valuable electrophysiological data.
• The MHN assessment is reliable and technically simpler than the DTN assessment.
• These techniques are promising tools for the diagnosis and management of trigeminal nerve disorders.