Brainstem Lesions

Question 1

Pontomedullary Syndrome

Answer 1

Lesion of the nucleus or the nerve
Multiple cranial nerve deficits ( CN 5,6,78,9,10,12, 11)
Hemiparesis to tetroparalysis
* ipsilateral limb deficits
* UMN to all limbs

mass lesions may impact brainstem and cerebellum concurrently

Question 2

Midbrain Syndrome

Answer 2

Depression, coma
Hemiparesis to tetraplegia (contralateral limb deficits with UMN signs)
CN3 deficits
Hyperventilation
Cavernous sinus syndrome (CN 3, 4, 5, 6)

Question 3

Hypothalamic syndrome

Answer 3

Behavior changes
Cranial nerve 2 deficit
Abnormal temperature regulation
Abnormal appetite
Central diabetes insipidus
Normal gait

Question 4

Components of Vestibular System
Peripheral

Answer 4

Vestibulocochlear nerve (CN8)
Vestibular apparatus

Question 5

Components of Vestibular System
Central

Answer 5

Brainstem: vestibular nucleus
Cerebellum: Caudal cerebellar peduncle, ipsilateral flocculonodular lobe

Question 6

Vestibular Syndrome

Answer 6

Increased extensor tone on side opposite of lesion
Head tilt, falling, rolling
Walking in tight circles
Nystagmus
Ventrolateral strabismus on ipsilateral side
Motion sickness
Must differentiate peripheral vs. central

Question 7

Peripheral Vestibular Syndrome

Answer 7

Loss of balance, head tilt, falling VL strabismus

Nystagmus can be:
* Horizontal or rotary
* Rarely is it vertical, on occasion in can be induced
* Contant when present
* Slow phase toward the lesion
* Faster than central vestibular nystagmus

Possible CN7 deficits, Horner’s

Question 8

Central Vestibular Syndrome

Answer 8

Loss of balance, head tilt, falling, VL strabismus

Nystamus:
* Horizontal, rotary, or vertical
* Inducible in different positions (upside down)
* Changing nystagmus

Conscious proprioceptive deficits confirms CVS
Cranial nerve deficits:
* Possible CN 5, 6, 7 or 9, 10, 12
* Deficit other than 7 confirms CVS

Question 9

Disease of the Peripheral Vestibular System:
Congenital Vestibular Disease

Answer 9

Dogs and cats, lumphocytic labyrinthitis
Viral?

Question 10

Disease of the peripheral Vestibular System
Neoplasia

Answer 10

Peripheral Nerve sheath tumor
Ceruminous gland ACA
Other

Question 11

Disease of The peripheral Vestibular Disease
Otitis media / interna

Answer 11

Most common cause
Otoscopic exam, CT, MRI
Culture if possible
Bulla osteotomy

Question 12

Idiopathic Vestibular Disease

Answer 12

Old dogs, cats of any age
No evident structural, metabolic or inflammatory disease
Acute to peracute onset head tilt, nystagmus, rolling
Rapid recovery:
* noticeable improvement in 24-48 hours
* Normal within 2-3 weeks
* Residual head tilt

Supportive care:
* Maropitant, Diphenhydramine, Meclizine, Diazepam

Question 13

Disease of the Central Vestibular System

Answer 13

Neoplastic: any type of CNS neoplasia
Infectious disease: canine distemper virus encephaloyelitis, rocky mountain spotted fever, Bacterial and Fungal meningoencephalitis
Primary systemic vasculitis
Granulomatous mengioencephalitis
Metronidazole toxicity

Question 14

Cerebellar Syndrome

Answer 14

Lesions are ipsilateral to abnormalitiy
Dysmetria
Truncal ataxia
Intention tremors
Broad based stance
Ataxia with preserved strength
Abnormal postural reacitons
Menance deficits with intact vision and PLR