Encephalopathies, Pt. 3 Flashcards
How do infectious encephalopathies typically progress?
rapidly!
What is corticosteroid-responsive tremor syndrome? What signalment is most commonly affected?
“White Shaker Dog” syndrome with fine whole-body or cerebellovestibular tremors
young adult (< 5 y/o) small breeds, typically Malteses and WHWTs
How do patients with corticosteroid-responsive tremor syndrome appear on diagnostics? How is it treated?
typically not done - MRI normal, CSF normal or mild mononuclear pleocytosis
Prednisone —> weaned slowly off
2 y/o MC Chihuahua presents with acute onset of shaking and balance loss. He appears hot, but it is Fall in NY. What is his most likely diagnosis? How would this be treated?
corticosteroid-responsive tremor syndrome
- Prednisone
- short course of low dose oral Diazepam
- Pu Ji Xiao Du Yin
What is thought to cause granulomatous meningoencephalomyelitis (GME)? What signalment is most commonly affected? How does it typically present?
suspected autoimmune inflammatory CNS disorder
middle-aged, female, small breeds - especially Mini/Toy Poodles
cerebellovestibular dysfunction
What tentative and definitive diagnostics are used for GME?
TENTATIVE - CT/MRI, CSF, matching signalment, clinical signs
DEFINITIVE - characteristic histopathological features of lesions predominantly in the white matter, usually at necropsy
How is GME most commonly treated? What are 4 adjunctive treatments recommended?
Prednisone 1-2 mg/kg PO BID
- Leflunomide - antiinflammatory
- Procarbazine - chemo
- Cytosine arabinoside - chemo
- Cyclosporine - immunosuppressant
What is the prognosis of GME like?
- poor historically, overall median survival of 14 days
- focal GME more favorable than multifocal
- prednisone alone is often ineffective
How is Cyclosporine used to treat GME? What side effects may occur?
lipophilic peptide that blocks inflammatory cytokines - MST 2.5 yrs
- vomiting
- diarrhea
- alopecia
- shedding
How is Procarbazine used to treat GME? What side effects may occur?
oral antineoplastic - MST 14 months
- myelosuppression
- hemorrhagic gastroenteritis
How is Azathioprine used to treat GME? What side effects may occur? How is it unique to other treatments?
purine analogue that inhibits DNA synthesis and miosis - MST 5 yrs
- bone marrow suppression
- GI signs
- hepatotoxicity
lag time to clinical effect
How is Cytosine arabinoside used to treat GME? What side effect is of concern?
nucleoside analog that is able to cross the BBB - SQ and IV CRI administration most common
myelosuppression
(MST > 1 yr)
How is Leflunomide used to treat GME?
pyrimidine analogue - safe in dogs, efficacy questionable
What are the 2 forms of necrotizing encephalitis (NE) of small breeds?
- PUG/MALTESE - forebrain dysfunction
- YORKSHIRE - forebrain and brainstem dysfunction
- many breeds affected
What imaging is used to diagnose NE of small breeds?
- CT - hypodense lesions
- T1-weighted MRI - usually not contrast-enhancing
What treatment is recommeded for NE of small breeds? How does it compare to GME?
Prednisone + antineoplastics and immunosuppressants
treatment efficacy decreased —> prognosis is poor
What drug has seen some success in treating NE of small breeds?
Mycophenolate mofetil (MMF) - immunosuppressant
What are some causes of infectious encephalitides?
- VIRAL: distemper in dogs, coronavirus in cats
- FUNGAL: crypto in NY
- Rickettsial
- Protozoal
What treatment is recommended for bacterial meningoencephalitis?
broad-spectrum antibiotics
- surgery may be requires
- patients tend to decompensate while DVMs ponder if it is bacterial
What is a common cause of fungal meningoencephalitis? How do patients typically present?
Cryptococcus —> bird poop
linger for months, then spiral quickly
What treatment is recommended for fungal meningoencephalitis? What concurrent treatment is recommended temporarily?
Fluconazole - kills fungus, but can cause intense inflammatory response
Prednisone
What are 3 common causes of viral meningoencephalitis?
- canine distemper virus
- FIP - coronavirus
- rabies virus
What are 3 common causes of protozoal meningoencephalitis? What treatments are recommended?
- Toxoplasma gondii
- Neospora caninum
- Sarcocystis
Clindamycin or Sulfonamides with Trimethoprim or Pyrimethamine
What are 3 other infectious causes of meningoencephalitis?
- Ricketssial - RMSF, Ehrlichia
- parasites - Cuterebra in cats
- Prototheca
What are 3 origins of primary brain tumors?
- brain parenchyma - glial cells and neurons
- meninges and ependyma
- vascular
What are the 3 most common primary brain tumors?
- meningioma
- glioma - astrocytoma, oligodendroglioma
- choroid plexus tumors
What are some other primary brain tumors?
- ependymoma
- olfactory neuroblastoma
- gliomatosis cerebri
- primary histiocytic sarcoma
- PNET
- medulloblastoma
- microglial tumors
What is the most common signalment affected by primary brain tumors? What is the most common complaints in dogs and cats?
9 y/o dogs, >10 y/o cats
- DOGS = seizures
- CATS = behavior changes
What are the most common primary brain tumors in dogs and cats?
DOGS = meningiomas and gliomas
CATS = meningiomas
What is important to consider when diagnosing primary brain tumors?
often occupy more than one anatomic regions of the brain —> nearly 1/4 have another tumor type elsewhere
What are the most common sites of astrocytomas?
diencephalon* and cerebellum
How do canine meningiomas compare to feline ones? What are all gliomas considered?
canine meningiomas are much more aggressive - 80% are atypical histologically
aggressive!
What is the most common site for choroid plexus tumors in dogs? What are the 2 most common types?
4th ventricle
- choroid plexus papilloma (CPP)
- choroid plexus carcinoma (CPC) - lateral ventricle most common, exhibit intraventricular or subarachnoid (drop) metastasis
What are important aspects of diagnosing primary brain tumors in dogs and cats?
- signalment
- history
- neuro exam
- advanced imaging (MRI, CT)
- histopathological confirmation
What are the 2 most common breeds of dogs affected by primary brain tumors? What tumors do these breeds tend to get? What age is most commonly affected?
- GOLDEN RETRIEVERS and other dolicephalics - meningiomas, choroid plexus tumors (GR)
- BOXERS and other brachycephalics - gliomas
older - 9 y/o
What primary brain tumor are Pembroke Welsh Corgis predisposed to?
intracranial histiocytic sarcoma
What is the most common signalment in cats affected by primary brain tumors? What type of tumor is most common?
- > 10 y/o
- male predilection
- no breed predilection
meningiomas
What is the most common historical feature in patients with primary brain tumors? What tends to cause rapid development?
progressive neurologic dysfunction over weeks to months, especially with meningioma
hemorrhage, exhaustion of compliance mechanisms, herniation
What is the top complaint in dogs and cats with primary brain tumors?
DOGS = seizure activity
CATS = behavior change
What cat-specific historical features are common with primary brain tumors?
NON-SPECIFIC - lethargy, inappetence, anorexia
- no obvious attributable clinical signs - incidental finding on necropsy
How is tumor location determined? Where are most found? What do all patients typically show on physical exam?
neurologic exam findings
forebrain - markedly asymmetric
neck and head pain on palpation
What is the most common advanced imaging used to diagnose primary bone tumors? What is required for definitive diagnosis?
MRI* or CT
histopathology
Why isn’t CSF analysis commonly used to diagnose primary brain tumors? When can it be used?
usually of no benefit and present potential danger
CPP/CPC differentiation
What are 4 common MRI appearances of intracranial meningiomas?
- broad-based, extra-axial attachment with distinct tumor margins
- uniform contract enhancement, unless there is a cystic component
- displace tissue - expansile
- “dural tail” - thickening and enhancement of the dura
What are 4 common MRI appearances of intracranial gliomas?
- intra-axial location with indistinct tumor margins
- infiltrative
- non-uniform and often poor contrast enhancement
- areas of hemorrhage and ring enhancement
What are 2 common MRI appearances of intracranial choroid plexus tumors? What is common with CPCs?
- intraventricular location
- uniform contrast enhancement
intraventricular metastases
What supportive therapies are recommended for brain tumors?
- Prednisone
- anticonvulsants if seizing
- additional pain medications as needed
What is the survival time like for patients with primary brain tumors on supportive therapy? How does location affect this?
typically 1-6 months —> avg 2 moths
- SUPRATENTORIAL = 6 months
- INFRATENTORIAL = 1 month
What are the 3 options for definitive treatments of brain tumors?
- surgery
- radiation
- chemotherapy
What tumors are typically removed surgically?
surface-oriented masses over the serebral or cerebellar convexities —> usually feline meningiomas (only treatment!)
- not performed as frequently for canine meningiomas
What is radiation therapy for brain tumors like?
- total administration of 50 Gy
- typically administered over 4 weeks in fractions, M-F
What “new-school” type of radiation therapy is used for brain tumors? How does this compare to old-school radiation therapy?
stereotactic radiosurgery with cyberknife or gamma knife
- more precise
- fewer treatments (2-5)
- more favorable results!
What 2 chemotherapies are used for brain tumors?
- oral Lomustine - canine gliomas
- oral Hydroxyurea - meningiomas
What kind of substance is Lomustine? What side effects are associated?
nitrosourea compound able to cross the BBB to treat canine gliomas
- bone marrow suppression
- hepatotoxicity
