21-22 Forebrain

8 CS unique to forebrain

• behavior change - esp cats

• head turn

• circling - compulsive and wide → towards lesion

• seizures - tonic and clonic seizures

• contralateral deficits - sensory and menace is opposite, hemineglect syndrome

• limbic system effects - emotions are more a human thing

• hypothalamic CS - homeostasis

• head pressing

pediatric vs adult hydrocephalus

Peds

• dilated ventricles (lat) that expand skull

• “dumb” toy breed dogs with dome heads

• CS: ataxia, proprioceptive defects, seizures, ventrolateral strabismus

Adult

• dilated ventricles → CSF squishes and clogs brain

• causes: neoplasia of ventricles, head trauma, encephalitis

what disease

hydrocephalus - peds

what is this tumor causing

hydrocephalus - adult

dx hydrocephalus

• ultrasound on persistent fontanelle

• MRI

• CT

tx hydrocephalus

• steroids, diuretics + omeprazole

• ventriculoperitoneal shunt sx

2 causes of hepatic encephalopathy (HE)

• liver failure

• PSS

CS and dx of HE

• waxing and waning forebrain CS that is worse after eating food

• liver fxn - chem, bile acids, ammonia

• ultrasound

• portal scintigraphy

Tx of HE

• low protein diet

• lactulose

• abx

• sx - ask tobias

2 Hypoglycemia causes

• excess insulin -insulinoma, insulin OD

• inadequate glucose - young animals

neuro CS of hypoglycemia

• Dilated pupils

• Tremor → seizures

• Seizures

• Behavior changes

• Blindness - No menace

• Weakness

Dx and Tx of hypoglycemia

• Dx: CS, low BG

• Tx: admin glucose

how to dx brain tumors

• MRI > CT

  • most tumors can see on MRI

  • CT for large tumors or cat meningioma

Tx brain tumors

• pred for edema

• sx to excise, debulk, biopsy - location dependent

  • cat meningioma

• radiation with sx or alone

#1 brain tumor of cats

meningioma

where is meningioma located and how do we tx

• extra axial (outside the brain), well defined

• Tx: Sx + radiation

Gliomas

• what breed

• location

• Tx

• brachycephalic

• intra-axial with tendrills

• Tx: Radiation > Sx

Macroadenoma

• location

• features

• Tx

• pituitary - cushing dogs→ ACTH secreting

• blindness - press on optic chiasm

• Tx: radiation > hyposthectomy

Trigeminal nerve sheath tumor

• CS

• Dx

• Tx

• CS: unilateral atrophy temporalis and masseter, absent facial sensation, brainstem dysfunction, good retractor bulbi reflex

• Dx: CT, MRI

• Tx: Radiation - poor prognosis even with tx

who get the infection vs immune mediated version of GME

• dog - immune mediated

• cat and young animals - infection

GME can have clinical signs from what aspects of the CNS

• forebrain: seizures, circling, blindness

• vestibular: head tilt

• SC: paresis, looks like IVDD

Dx of GME

• MRI - bright BBB

• CSF analysis

  • milky, > 5 cells, > 25-30 protein, high WBC (mononuclear or mixed cells)

NME is common in what breeds and where is it localized to

• Pugs, Maltese, Yorkies, other small breeds

• Brain: Circling, blindness, seizures, hemiparesis

Dx NME

CT - focal necrosis areas filled with CSF

How to tx GME, NME and what is the prognosis rule

• PRED ± cytosine arabinoside or cyclosporine

• prognosis:

  • 1/3 respond and cure

  • 1/3 respond but relapse and need lifelong meds

  • 1/3 die

how does distemper affect young vs old dogs

• Young dogs: systemic illness, acute encephalitis

• Adult dogs: chronic encephalitis (recrudescence)

CS of distemper

• Hyperkeratosis of paws

• Nose crusty/snotty

• Myoclonus - rhythmic flexion/extension bouncy dance

Dx of distemper

• Retinochoroiditis

• Lymphopenia

• Serology (best) – vx confounds results

• CSF – mononuclear pleocytosis; Ab to distemper

FIP

• cause

• CS localization

• Dx

• mutated coronavirus - dry form = neuro

• CS: vestibular, SC, forebrain

• Dx: MRI - big ventricles and bright rims of 3rd and 4th ventricles

3 other infectious encephalitis to test for

• Tick-born infections: Rocky Mountain Spotted Fever, E. canis

• Fungal: cryptococcus, blastomyces, coccidiomycosis, histoplasma

• Protozoan: Toxoplasma, Neospora

CS of cuterebra and what on dx cues you into thinking this is a parasite in the forebrain

• resp signs at first

• acute circling, hemiparesis, blindness, seizures

• Dx: eosinophilic CSF

8 toxins that can cause forebrain CS

• Lead

• Ethylene glycol

• Mycotoxins

• Organophosphates, carbamates

• Pyrethrins

• Bromethalin

• Strychnine

• Sago Palm

where can strokes happen and what is the pathophys

• brain or SC

• ischemia to parts of the brain —> focal lesions —> infarction once that area necrosis

CS, Dx, Tx of stroke

• CS: seizures, circling, hemiparalysis, head tilt, ataxia

• Dx: CS, MRI

• Tx: supportive (TIME) and tx underlying cause