Brain Diseases in the Dog and Cat Flashcards
What are the 3 main causes of intracranial dysfunction?
- Primary lesion in the cranium
- Secondary intracranial pathophysiological sequelae to a focal lesion: hemorrhage, obstruction of the ventricular system, edema formation, “cascade of cellular events” = progressive neuronal damage both locally and globally due to impaired oxygen. and glucose delivery, resulting in impaired ATP production and failure of neuronal membrane pumps and excitotoxicity
- Global CNS dysfunction as a consequence of extra-cranial systemic disease
Why does increased intracranial pressure lead to impaired neuronal function?
- Directly Impacts: ischemia/ trauma to the cerebral vessels/ hemorrhage +/- obstruction of CSF flow
- Indirectly Impacts: Will then get a systemic elevation of catecholamines to maintain cerebral blood flow –> hypertension
Sympathomimetics predispose to arrhythmia
Can lead to brain herniation out of the foramen magnum
What are the clinical signs associated with Brain Herniation out of the foramen magnum?
- Rapid deterioration in clinical signs
- Deterioration in mental status/ paresis
- Bradycardia + systemic hypertension
- Pupil changes + respiratory changes
What are the clinical signs associated with Cerebral Syndrome?
- Normal gait
- Altered mental status: apathy, depression, disorientation, lethargy, coma
- Change in behavior: loss of training, failure to recognize owner, aggression, hyperexcitability
- Abnormal movements/ postures: pacing, wandering, circling, head-pressing, twisted head + trunk
- Postural reaction deficits in contralateral limbs
- Visual impairment: a contralateral deficit in the menace, but normal palpebral reflex
- Seizures
What are some differentials for Cerebral Syndrome?
DAMNITV
D: Canine cognitive dysfunction, storage diseases
A: Hydrocephalus/ Lissencephaly
M: Hypoglycemia/ Hepatic Encephalopathy
N: Primary + Secondary neoplasia, Thiamine deficiency
I: Protozoal/ Bacterial/ Viral infection, Meningitis of Unknown Origin (GME/ NME), Epilepsy
T: Toxins (plants, ethylene glycol, lead, xanthines, RTA
V: Infarct/ hemorrhage
What is Canine Cognitive Dysfunction?
This is classified as a behavioral syndrome that affects older dogs (8+ years old), resulting in behavioral alterations: disorientation/ confusion, altered interactions with the owner or other pets, sleep-wake cycle disturbances, house-soiling and changes in activity
Vision impairment, smell disturbance, tremor, swaying or falling and head ptosis are physical signs of CCD, and may be useful in the early stages of CCD
“Analogous to human Alzheimer’s Disease”
What are the proposed causes of Canine Cognitive Dysfunction?
- Brain vascular damage
- Deposition of beta-amyloid protein
- Oxidative injury
- Neuronal mitochondrial dysfunction
- Excitotoxic neuronal damage
- Inflammation
Are there any treatments or supplements that can be given to a dog with Canine Cognitive Dysfunction?
- Balanced and fortified diet
- Antioxidants
- L-deprenyl (Selegiline)
- Cognitive Enrichment: interactive games such as puzzle toys
What are the possible Inflammatory diseases, and Infectious agents involved in forebrain inflammation?
Inflammatory Diseases:
- Meningitis of Unknown Origin (MUO)
- GME (granulomatous meningoencephalomyelitis), NME (necrotizing meningoencephalitis)
Infectious Agents:
- Viral: Distemper, FIP, Rabies
- Bacterial
- Protozoal: Toxoplasma/ Neospora
- Rickettsial: Ehrlichia, Rocky Mountain Spotted Fever (Anaplasma phagocytophylum)
- Fungal: Blastomycosis, Aspergillosis
- Unclassified: Protothecosis (type of algae)
How can Meningitis of Unknown Origin (e.g. GME and NME) be diagnosed?
- Biopsy + Histopathology of nervous tissue is required for definitive diagnosis
- CSF Fluid may help
- MRI + CT
What is the treatment for Meningitis of Unknown Origin (e.g. GME and NME)?
Immunosuppressive Therapy + Control of seizures if present
Prednisolone +
- Cytosine arabinoside
- Ciclosporine
- Procarbazine
What are the most common causes of cerebrovascular damage?
1) Infarct: due to a hyper-coagulable state or hypertension
2) Hemorrhage: due to trauma, coagulopathy or angiostrongylus
Both infarct and hemorrhage will lead to a disruption of blood flow to the brain tissue, causing cell death + stroke
What common toxins cause CNS stimulation?
Strychnine Metaldehyde Xanthines Organochlorines Cocaine
What common toxins can cause a mixed clinical effect? (either CNS stimulation and/or CNS depression)
Lead
Pyrethrins
Ethylene glycol
Mushrooms
What common toxins can cause CNS depression?
Opiates
Marijuana
Ivermectin
What are Lysosomal Storage Diseases?
These are inherited disorders resulting from a lack of specific enzymes that break down certain fats, proteins and CHOs in the body cells
What are the clinical signs associated with Lysosomal Storage Diseases?
- Cerebellovestibular signs: ataxia, incoordination, changes in attitude, seizures, tetraparesis, intention tremor and blindness
- Signs usually appear within the first few months of life and progressively worsen over the first year (but some do occur later in life)
How can Lysosomal Storage Diseases be diagnosed?
- Signalment: young animal, of a susceptible breed that progressively worsens with a symmetrical neurologic disorder
- Genetic tests are available: PennGen/ Laboklin
- Definitive test: biopsy + histopathology
What is the diagnostic approach to animals with suspected Intracranial Disease?
1) Complete history, physical exam + neurologic assessment: a focal or asymmetric deficit suggests intracranial disease
2) Rule out Metabolic encephalopathies: Hematology + Biochem, Urinalysis, Blood glucose, liver function test
3) Evaluate for systemic inflammatory or neoplastic disease: complete ophthalmic exam, thoracic + abdominal rads, abdominal U/S, aspirates of lymph nodes
4) Intracranial exam: CT + MRI, CSF collection and analysis
Why does Thiamine deficiency cause neurological disease?
Thiamine (B1) is important in normal CHO metabolism and synthesis of neurotransmitters