Cranial Neuropathy Flashcards
Trigeminal nerve disorders
Could be idiopathic trigeminal neuropathy
Or caused by neoplasia
Intracranial portion of CN V is susceptible to diseases that affect the brain
Sensory signs for trigemnial neuropathy
Reduced / abnormal facial sensation
Reduced palpebral, corneal, lip pinch, nasal sensation
Motor signs for trigeminal neuropathy
Atrophy of muscles of mastication
Masticatory muscles paresis/paralysis
Dropped jaw - with bilateral lesions*
Idiopathic trigeminal neuropathy
Aka trigeminal neuritis
More common in dogs than cats
Acute onset of dropped jaw, drooling, abnormal facial sensation, mast muscle atrophy
Other differentials for trigeminal neuritis I
Neoplasia - lymphoma
Infectious - rabies
Diagnosing CN V neuritis
History, signs, work up
Negative for 2M antibody
MRI & CSF - trigeminal nerves may appear abnormal
Treatment for CN V neuritis
Supportive therapy
Usually resolves without specific treatment
Trigeminal neoplasia
Primary or secondary neoplasia
Lymphoma or nerve sheath tumor
Diagnosis in 50% of dogs w unilateral trigeminal neuropathy
Facial nerve disorder causes
Metabolic
Neoplasia
Idiopathic facial nerve paralysis
Infectious
Trauma
(Facial nerve is closely associated with CN VII)
Facial neuropathy clinical signs
Facial paresis or paralysis - lips, eyes, lack of ear movement
Parasympathetic - dry eye/nose
Sensory - medial surface of pinna, abnormal test
Chronic facial neuropathy
Can see contraction of muscles, deviation TO the abnormal side
Idiopathic facial nerve paralysis
Occurs in dogs & cats
Acute, unilateral, facial nerve paresis
Exam results would be consistent w unilateral facial nerve paresis
Diagnosing idiopathic facial nerve paralysis
Rule out other causes
Otoscopic exam
MRI/CSF
Treat with artificial tears to prevent development of keratitis
Prognosis is usually good
Otitis media/interna
Facial neuropathy can occur with otitis
Except vestibular signs
Can except horner’s syndrome esp in cats
Hypothyroidism
Has been linked to facial, trigeminal and vestibular signs
May also cause a polyneuropathy
Common in older large breed dogs
Clinical signs for hypothyroidism
May or may not have hypo clinical signs
Neuropathy of any of the nerves mentioned
Diagnosis should be compatible clin signs
Treat the hypo & prognosis should be fair to good
Vestibular nerve disorders
Hypothyroidism
Neoplasia
Otitis media interna
Polyp
Idiopathic
Toxin
Often see vestibular dysfunction w intracranial disease
Clinical signs of vestibular disease
Head tilt, leaning, rolling
Nystagmus
Circling - tight
Strabismus
Ataxia
Nausea
Cochlear nerve disorders
Degenerative
Congenital hearing loss
Inflammatory - otitis
Toxins
- furosemide
- aminoglycosides
- chlorhexidine
Cochlear clinical signs
Hearing loss
Conductive - failure of sound transmission through the inner ear - otitis media interna
Sensorineural - failure of sound transduction by organ of corti of failure of cochlear nerve - congenital deafness
BAER
Brainstem auditory evoked response
Test of hearing/brainstem function
Performed awake or sedated
Can be sued to differentiate types of hearing loss
Hypoglossal nerve disorders
Caused by neoplasia or inflammation
Hypoglossal clinical signs
Paresis & paralysis of tongue - unilateral or bilateral
Difficulty prehanding food
Generally tongue deviates towards affected side
