Brainstem Disease

Question 1

What is Pontomedullary syndrome?

Answer 1

• Lesion of the nucleus (intra-axial lesion) or the nerve (extra-axial lesion)
• Multiple cranial nerve deficits
  
  • 5, 6, 7, 8 (Central vestibular)
  • 9, 10, 12 (nucleus ambiguus)
  • 7, 9, 10, 11, 12 are closely associated in the skull
• Hemiparesis to tetraparalysis
  
  • ipsilateral limb deficits
  • UMN to all limbs
• Mass lesions may impact brainstem and cerebellum concurrently

Question 2

What is Midbrain syndrome?

Answer 2

• Depression, coma
• hemiparesis to tetraplegia
  
  • Contralateral limb deficits with UMN signs
  • Massive lesion ⇢ decerebrate rigidity (opisthotonos)
• CN3 deficits (ophthalmoplegia, mydriasis)
• Hyperventilation (respiratory alkalosis)
• Cavernous sinus syndrome: CN 3, 4, 5, 6

Question 3

What is Hypothalamic syndrome

Answer 3

• Behavior changes
• CN2 deficits (variable)
• Abnormal temperature regulation
• Abnormal appetite
• Central diabetes insipidus
• Normal gait

Question 4

What are the components of the vestibular system?

Answer 4

• Peripheral
  
  • Vestibulocochlear nerve (CN8)
  • Vestibular apparatus (semicircular canals, utriculus, sacculus of inner ear)
• Central
  
  • Brainstem: vestibular nucleus (4 on each side)
  • Cerebellum: caudal cerebellar peduncle, ipsilateral flocculonodular lobe

Question 5

What is Vestibular Syndrome?

Answer 5

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

Question 6

What is Peripheral Vestibular syndrome?

Answer 6

• Loss of balance, head tilt, falling, VL strabismus
• Nystagmus can be:
  
  • horizontal or rotary
  • Rarely is it vertical, on occasion it can be induced
  • Constant when present
  • Slow phase toward lesion
  • Faster than central vestibular nystagmus
• Possible CN7 deficits, Horner’s

Question 7

What is Central Vestibular Syndrome?

Answer 7

• Loss of balance, head tilt, falling VL strabismus
• Nystagmus
  
  • Horizontal, rotary, or vertical
  • inducible in different position (upside down)
  • Changing nystagmus
• Conscious proprioceptive deficits confirms CVS
• Cranial nerve deficits:
  
  • Possible CN 5, 6, 7 (or 9, 10, 12)
  • Deficits other than 7 confirm CVS

Question 8

What diseases are common in the Peripheral Vestibular System?

Answer 8

• Congenital vestibular disease
  
  • Lymphocytic labyrinthitis
• Hypothyroidism
• Neoplasia
  
  • peripheral nerve sheath tumor
  • Ceruminous gland ACA
• Otitis media/interna
  
  • Most common cause
  • Otoscopic exam, CT, MRI
  • Culture if possible
  • Bulla osteotomy
• Otic medications

Question 9

What is Idiopathic Vestibular Disease? etiology? treatment?

Answer 9

• Acute to peracute onset head tilt, nystagmus, rolling
• No evident structural, metabolic or inflammatory disease
• Affects old dogs, cats of any age
• Rapid Recovery
  
  • Noticeable improvement in 24-48 hours
  • Normal within 2-3 weeks
  • Residual head tilt
• Supportive Care
  
  • Maropitant, Diphenhydramine, Meclizine, Diazepam

Question 10

What are some diseases of the Central Vestibular System?

Answer 10

• Neoplastic: any type of CNS neoplasia
• Infectious disease
  
  • Canine distemper virus encephalomyelitis
  • Rocky Mountain Spotted fever (other rickettsials)
  • Bacterial and fungal meningoencephalitis
• Primary systemic vasculitis
• Granulomatous meningoencephalitis and other MUE
• Metronidazole toxicity

Question 11

What are the signs of Cerebellar Syndrome?

Answer 11

• Dysmetria (hypermetria)
• Truncal ataxia
• Intention tremors
• Broad based stance
• Ataxia with preserved strength
• Abnormal postural reactions
• Menace deficits with intact vision and PLR

Question 12

Where are the lesions in cerebellar syndrome?

Answer 12

ipsilateral to abnormality

Question 13

What are some diseases of the Cerebellum?

Answer 13

• Cerebellar cortical atrophy
• Cerebellar abiotrophy
• Neuroaxonal dystrophy
• Cerebellar hypoplasia
  
  • Hereditary
  • Congenital
• Caudal occipital malformation syndrome
• Neoplasia
• Infectious
  
  • Canine herpes virus
  • Feline panleukopenia
  • Canine distemper virus
  • FIP
  • Fungal, rickettsial, protozoal, algal
• Primary systemic vasculitis
• Lysosomal storage disease
• Vascular accident