Localization within the Skull

Where can a pontomedullary localization be?

Lesion of the nucleus or of the nerve

What are the vestibular nerve deficits?

5,6,7,8 cranial nerves

Where do you expect there to be multiple cranial nerve injured?

If there is a lesion in the axial

What can we get with a midbrain lesion?

Depression or coma

What type of paralysis can a midbrain lesion cause?

Hemiparesis or tetraplegia

Contralateral limb deficits with UMN digns

What C/S do you have with a midbrain lesion?

CN 3 deficits

Hyperventilation

What does cavernous sinus syndrome effect?

CN 3, 4, 5, 6

What are the C/S of a hypothalamic lesion?

Behavior changes

CN 2 deficits

Abnormal temperature regulation

Abnormal appetite

Central diabetes insipidus

Normal gait

What are the signs of thalamic disease?

Vestibular ataxia

Contralateral menace deficits

Circling

Contralateral proprioceptive deficits with paresis/plegia

Head tilt

Hypermetria

Behavioral abnormalities, alterations in consciousness

Nonspecific pain

Vision deficits

What are the peripheral components of the vestibular system?

Vestibulocochlear nerve (CN 8)

Vestibular apparatusW

hat are the central components of the vestibular system?

Brainstem: vestibular nucleus

Cerebellum: caudal cerebellar peduncle, ipsilateral flocculonodular lobe

What are some clinical signs of a vestibular lesion that will help you localize it?

Head tilt

Walking in tight circles

Nystagmus

Increased extensor tone on side opposite of lesion

Motion sickness

What does peripheral vestibular disease look like?

Loss of balance, head tilt, falling, VL strabismus

Nystagmus (slow phase towards lesions, fast)

Possible CN 7 deficits (Horner’s)

What does vertical nystagmus indicate?

Central vestibular disease

What does central vestibular disease (CVS) look like?

Loss of balance, head tilt, falling, VL strabismus

Nystagmus

Conscious proprioceptive deficits confirms CVS

Cranial nerve deficits (CN 5,6,7). Anything other than 7 confirms CVS and not PVS

What are some diseases of the peripheral vestibular system?

Otitis media/interna

Congenital vestibular disease

Hypothyroidism

Neoplasia

Otic medication

What animal is most likely to have idiopathic vestibular disease?

Old dog and cats of any age

What causes idiopathic vestibular disease?

No evident structural, metabolic, or inflammatory disease

What are the C/S of idiopathic vestibular disease?

Acute to peracute onset head tilt, nystagmus, rolling

Rapid improvement in 24-48 hours

What can you do to assist with idiopathic idiopathic vestibular disease?

Supportive care

• Maropitant

• Diphenhydramine

• Meclizine

• Diazepam

What are some diseases of the central vestibular system?

Neoplasia

Infectious: Canine distemper, rocky mountain spotted fever, bacteria or fungus

Primary systemic vasculitis

Granulomatous meningoencephalitis

Metronidazole toxicity

What can you use to combat metronidazole toxicity?

Diazepam CRI

What are some signs of a cerebellar lesion?

Dysmetria

Truncal ataxia

Broad based stance

Ataxia with preserved strength

Abnormal postural reactions

Menace deficits with intact vision and PLR

T/F cerebellar lesions are ipsilateral to abnormality?

True

What are some diseases of the cerebellum?

Degenerative

Cerebellar hypoplasia

Neoplasia

Infectious (canine herpes, feline panleukopenia, protozoa)

Primary systemic vasculitis

Lysosomal storage disease

Vascular accident

What are some signs of cerebral disease that will help you localize it?

Gait abnormalities

Conformation (big circling and compulsive pacing)

Seizures

Contralateral limb and vision deficits

Behavior changes

What are some diseases of the cerebrum?

Brain tumors

Cerebral vascular accident (stroke)

Head trauma

Infectious disease

Lysosomal storage disease (young animals)

Congenital hydrocephalus (young animals)

What are some cerebellar diseases in older dogs and cats?

Senile atrophy

Cognitive dysfunction

Hypertensive encephalopathy

What systems does canine distemper encephalitis effect?

Cerebrum, cerebellum, optic tracts, spinal cord

What are some C/S of canine distemper encephalitis?

Blindness, seizures, central vestibular cerebellar, spinal cord, myoclonus

Hyperkeratosis of foot pads

Gold-medallion lesions of retina

How do you diagnose canine distemper encephalitis?

PCR (urine); CSF-mononuclear pleocytosis and increased CDV igG

What is steroid-responsive meningitis arteritis (SRMA)?

Aseptic meningitis

#2 inflammatory CNS disease

What dogs are most susceptible to SRMA (steroid-responsive meningitis arteritis)?

Young dogs that are large breed

What are the C/S of SRMA (steroid responsive meningitis arteritis)?

Neck pain

Fever

Stiffness

Ataxia

How can you diagnose Steroid-responsive meningitis arteritis (SRMA)?

CBC: leukocytosis w/ left shift

CSF: neutrophilic pleocytosis

Positive response to steroids?

How do you treat SRMA?

Immunosuppressive prednisone

What dogs are more likely to get bacterial meningitis, encephalitis?

Middle aged to older

What are the C/S of bacterial meningitis, encephalitis?

Peracute, acute, or gradual

Lethargy, reluctance to walk, anorexia

Neck pain, hyperthermia, bradycardia, depression, seizures

How do you diagnose bacterial meningitis?

Elevated WBC, CSF tap, culture

How do you treat bacterial meningitis?

Antibiotics that cross BBB (fluoroquinolones, 3rd gen cephs)

Steroids for first 24-48 hours

What can cause fungal meningoencephalitis?

Cryptococcus, histoplasmosis, blastomycosis

What animals can get fungal meningoencephalitis?

Dogs and cats

What are the C/S of fungal meningoencephalitis?

Similar to bacterial meningitis

Usually systemic

How do you diagnose fungal meningoencephalitis?

Fundic exam: fungal plaques

CSF, urine antigen testing, serology

How do you treat fungal meningoencephalitis?

Fluconazole, itraconazole, amphotericin B, posaconazole, voriconazole

What is MUE or MUO (meningoencephalitis of unknown etiology)?

Granulomatous meningoencephalitis (GME)

Necrotizing meningoencephalitides (NME)

Nonsuppurative inflammatory disease in the cerebrum and cerebellum, pons, medulla, spinal cord

Diffuse of coalescing lesions

What animals are susceptible to meningoencephalitis of unknown etiology?

toy breeds from 1-8 years old

How do you diagnose MUO?

Suspicion from C/S

CT, MRI

CSF: mononuclear mixed pleocytosis, elevated protein

How do you treat MUO?

Prednisone

Cyclosporine

Cytosine arabinoside

Leflunomide, mycophenolate

Antiepileptics

What is MUO stand for?

Meningoencephalitis of unknown origin

Describe strokes

A cerebrovascular accident

What can cause strokes?

Feline ischemic encephalopathy

Ischemic or hemorrhagic

Where can strokes effect in the brain?

Cerebral, thalamic, cerebellar, brainstem

What is the prognosis of strokes?

Dependent on etiology

Usually good long-term outcomes

30% have recurrent events

How do you manage strokes?

Mannitol or hypertonic saline in acute phase

Anti-epileptics if seizures

Treat underlying disease

Supportive

Nutrition is vital

What animals are susceptible to Chiari-like malformation?

Cavalier king charles spaniel, burssels griffon

What is chiari-like malformation?

Small caudal fossa causes the cerebellum to be displaced into brainstem

What are the clinical signs of chiari-like malformation?

Spinal pain, paresis, ataxia, facial scratching or rubbing, resentment of touching, grooming, variable limb deficits

How do you treat chiari-like malformation?

Corticosteroids, analgesia

Surgery to enlarge foramen magnum and caudal fossa

What are 3 metabolic ecnephalopathies?

Uremic encephalopathy

Hepatic encephalopathy

Hypothyroidism

What causes uremic encephalopathy?

Chronic renal failure

Hypertension, hyperparathyroidism

What causes hepatic encephalopathy?

Acute or chronic liver disease

Neurodepressive

Ammonia, benzodiazepine-like substances

What can cause lysosomal storage disease?

Hereditary disease due to

• Defect in lysosomal pathway

• Accumulation of intermediate metabolite

• Resultant cell death

How do you diagnose lysosomal storage diseases?

Clinical

MRI, CT scan

Genetic screening

Urine metabolite screen

Histopathology

How do you treat lysosomal storage disease?

Acetyl-I-carnitine

What are the C/S of lysosomal storage diseases?

Central and or peripheral nervous system disease

Hepatomegaly

Skeletal abnormalities

Young onset

What are some common CNS neoplasias?

Meningioma

Astrocytoma

Oligodendroglioma

Choroid plexus tumor

Ependyumal tumors

Describe meningiomas

Most common in older dogs and cats

Occur peripherally, midline, tentorial, ventral or lateral to brainstem within ventricles

Describe astrocytomas

Variable malignancy

Increased risk in brachycephalics

Describe oligodendroglioma

Common in males and brachycephalics

Usually in frontal lobes

Describe choroid plexus tumor

Arise in 4th ventricle, can occur in lateral and 3rd ventricles

How do you definitively diagnose CNS neoplasia?

MRI

T/F you can often treat CNS neoplasia on a most likely diagnosis with prednisone and phenobarbital for seizures?

True