Low Field MRI Measurements of the Normal Canine Trigeminal Nerve

Area of Science:

• Veterinary Neurology
• Medical Imaging
• Canine Anatomy

Background:

• Diagnosing canine trigeminal neuropathy is challenging due to the lack of established normal reference ranges for trigeminal nerve measurements.
• Bilateral trigeminal neuropathy cases are difficult to assess without reliable contralateral nerve comparisons.

Purpose of the Study:

• To establish a measuring protocol and reference ranges for normal canine trigeminal nerves using MRI.
• To develop objective assessment methods for canine trigeminal nerve health.

Main Methods:

• Retrospective analysis of 3D T1 post-contrast MRI sequences from 137 healthy dogs.
• Measurement of vertical brain height (BH), trigeminal nerve transverse height (TTH), and trigeminal nerve width (TDW).
• Derivation of trigeminal nerve-to-brain (NB) ratios: height-to-brain ratio (HBR) and width-to-brain ratio (WBR).

Main Results:

• Trigeminal nerve-to-brain ratios (HBR and WBR) showed more consistent values than direct measurements.
• Normal reference intervals for HBR and WBR were established as 0.07-0.11 and 0.08-0.13, respectively.
• NB ratios varied with dog weight and skull type, with smaller dogs and brachycephalic breeds exhibiting smaller HBRs.

Conclusions:

• Trigeminal nerve-to-brain ratios provide an objective method for assessing canine trigeminal nerves on MRI.
• Further research is needed to quantify the influence of weight and skull type on reference intervals.
• These ratios may aid in the diagnosis of trigeminal nerve disorders in dogs.