Trigeminal Neuropathy in Dogs: A Retrospective Study of 29 Cases (1991–2000)

Abstract

The medical records of 29 dogs unable to close their mouths due to flaccid paralysis or paresis of the muscles innervated by the mandibular branch of the trigeminal nerve, were reviewed. Idiopathic trigeminal neuropathy was diagnosed in 26 dogs based on complete resolution of clinical signs and lack of any long-term neurological disease. Of these dogs, golden retrievers were overrepresented. No age, sex, or seasonal predispositions were identified. Trigeminal sensory innervation deficits were observed in 35% (9/26), facial nerve deficits were observed in 8% (2/26), and Horner's syndrome was observed in 8% (2/26) of dogs. Electromyographic examination of the muscles of mastication revealed abnormalities in seven of nine dogs. Results of cerebrospinal fluid analysis were abnormal in seven of eight dogs. Corticosteroid therapy did not affect the clinical course of the disease. Mean time to recovery was 22 days. Lymphosarcoma, Neospora caninum infection, and severe polyneuritis of unknown origin were diagnosed in three of 29 dogs at necropsy.

Imaging diagnosis: chronic unilateral trigeminal neuropathy masquerading as a trigeminal peripheral nerve tumour on MRI in a dog

“…One retrospective study investigating the causes of trigeminal neuropathies diagnosed 26/29 cases as having idiopathic trigeminal neuropathy (ITN) (Mayhew and others 2002). ITN is usually associated with bilateral lesions of CN V and an inability of the animal to close the mouth.…”

“…Neoplastic lesions may include lymphoma, peripheral nerve sheath tumour (malignant peripheral nerve sheath tumour (MPNST) or benign peripheral nerve sheath tumour (PNST)) or myelomonocytic leukaemia. Infectious causes such as rabies or infectious encephalitis involving the motor nuclei of the trigeminal nerve bilaterally ( Neospora canis, Borrelia burgdorferi, Toxoplasma gondii and Listeria monocytogenes ) have been identified as potential causes (Bagley and others 1998, Platt and others 1999, Long and others 2001, Mayhew and others 2002, Schultz and others 2007). …”

“…Radiation therapy was considered; however, it is not a benign treatment modality and can be associated with various side effects, with most side effects being transient and resolving in two to three weeks after treatment has been completed (Mayer and Treuil 2007). It has been documented that no specific treatment is indicated in dogs with suspected ITN; the use of corticosteroids did not appear to affect the course of the disease in dogs (Mayhew and others 2002). This is contrary to human patients, where medical management of neuralgia is indicated, with carbamazepine shown to be very effective.…”

Diseases of the Motor Unit

“…Dogs with hypoadrenocorticism may manifest signs ranging from rear limb paresis to complete recumbency. 4 Treatment is supportive and the animal is fed by placing small meatball-shaped foods in the mouth with the head elevated. In both instances hyporeflexia occurs.…”

MR Signal Changes of Trigeminal Nuclei in a Case of Suspected Idiopathic Trigeminal Neuropathy in a Staffordshire Bull Terrier

“…1 Also referred to as idiopathic trigeminal neuropathy (ITN), trigeminal neuritis, and trigeminal neurapraxia, this condition primarily affects the motor branches of the trigeminal nerves bilaterally, although associated loss of facial sensation and Horner's syndrome are described. 2 The condition is self-limiting and is characterised by spontaneous full recovery. The published literature on magnetic resonance imaging (MRI) findings for this condition is limited to two cases, and describes non-specific changes within the trigeminal nerve.…”