Vet360 Vet360 Vol 05 Issue 04 - Page 23

NEUROLOGY Radiation therapy can provide long-term control. 10 Given the potential for long-term survival after radiation therapy in dogs with trigeminal nerve sheath neoplasms, it’s possible that the alteration in salivation may have a significant impact on the overall health and the quality of life of affected patients. It may be prudent to perform more frequent and thorough oral examinations to evaluate for pharyngeal function and salivary function in affected dogs. As the lack of autonomic functions to the head and face can lead to discomfort and secondary complications in our human patient counterparts, veterinarians should be aware of the potential for similar issues in dogs and cats. Figure 3. A transverse T1-weighted post-contrast MRI of Max's brain. A trigeminal nerve sheath neoplasm is compressing the brain stem (red asterisk) and is continuing along the mandibular branch as it exits via the oval foramen. Note the enlargement of the left oval foramen in comparison to the right. There is pronounced atrophy of the temporalis (large yellow arrow), masseter (small yellow arrow), digastricus (open yellow arrow) and pterygoid (yellow arrowhead) A common cause of unilateral trigeminal nerve dysfunction is a nerve sheath neoplasm. Other causes of trigeminal nerve dysfunction include trauma, infectious or noninfectious neuritis, and other forms of neoplasia such as lymphoma. A complete physical and neurological examination may help narrow the differential diagnoses. Magnetic resonance imaging (MRI) of the head is the best way to establish a definitive diagnosis. With trigeminal nerve sheath neoplasms, MRI findings include an enlargement of the trigeminal nerve or its main branches, which display contrast enhancement, enlargement of the oval foramen from pressure necrosis from the expansile growth of the mandibular nerve, compression or invasion of the pons by the neoplasm, denervation atrophy of the masticatory muscles, and effusion in the tympanic cavity (middle ear) (Figure 3). What to do next Treatment options for nerve sheath neoplasms include palliative therapy with anti-inflammatory drugs or definitive therapy with radiation therapy. 10,11 Current accepted practices in dental care may provide a starting point for monitoring and planning dental procedures in affected patients. 12 In the future, more tailored evaluation protocols, preventive care measures and therapeutic interventions may be developed to minimize the negative impact abnormal autonomic function has on oral and overall health and to maintain an excellent quality of life in affected patients. References 1. Evans HE, de Lahunta A. Cranial nerves. In: Evans HE, de Lahunta A, eds. Miller's anatomy of the dog. Philadelphia: Elsevier Saun- ders, 2012;708-730. 2. Maggs DJ, Miller PE, Ofri R. Diseases of the lacrimal system. In: Maggs DJ, Miller PE, Ofri R, eds. Slatter's fundamentals of veterinary ophthalmology. 6th ed. St. Louis, Missouri: Elsevier, 2018;186-211. 3. Nederfors T. Xerostomia and hyposalivation. Adv Dent Res 2000;14:48-56. 4. Evans HE, de Lahunta A. The digestive apparatus and abdomen. In: Evans HE, de Lahunta A, eds. Miller’s anatomy of the dog. Philadel- phia: Elsevier Saunders, 2012;281-334. 5. Evans HE, de Lahunta A. The autonomic nervous system. In: Evans HE, de Lahunta A, eds. Miller’s anatomy of the dog: Philadelphia: Elsevier Saunders, 2012;575-588. 6. Proctor GB, Carpenter GH. Regulation of salivary gland function by autonomic nerves. Auton Neurosci 2007;133:3-18. 7. Kent M, Glass EN, Song RB, et al. A salivation abnormality with trigeminal nerve dysfunction in dogs. J Vet Dent (in press). 8. Epstein JB, Scully C. The role of saliva in oral health and the causes and effects of xerostomia. J Can Dent Assoc 1992;58:217-221. 9. Einarson S, Gerdin EW, Hugoson A. Oral health-related quality of life and its relationship to self-reported oral discomfort and clinical status. Swed Dent J2014;38:169-178. 10. Swift KE, McGrath S, Nolan MW, et al. Clinical and imaging findings, treatments, and outcomes in 27 dogs with imaging diagnosed trigeminal nerve sheath tumors: A multi-center study. Vet Radiol Ultrasound 2017;58:679-689. 11. Bagley R, Wheeler S, Klopp L, et al. Clinical features of trigem- inal nerve-sheath tumor in 10 dogs. J Am Anim Hosp Assoc 1998;34:19-25. 12. Holmstrom SE, Bellows J, Juriga S, et al. 2013 AAHA dental care guidelines for dogs and cats. J Am Anim Hosp Assoc 2013;49:75-82. NVCG CPD: SURGERY National Veterinary Clinicians Group 12 Nov 14 Nov 20 Nov Johannesburg / Pretoria - Premier Hotel, Midrand Cape Town - Century City Convention Centre Durban - Westville Animal Hospital V SPEAKERS: Dr Sarah Boyd & Bonus Lecture on Practice management: Dr Lawson Cairns Register / more info: Issue 04 | SEPTEMBER 2018 | 23