Intracranial Disease 3 (toxic bc that's how you like it)

What is the pathogenesis of a lead toxicity in the brain?

How is it exposed to the brain?

Polioencephalomalacia

GI tract

What is the pathogenesis behind Organophosphates?

Acetylcholinesterase inhibitors = too much ACh at nicotinic and muscarinic receptors

What are the muscarinic clinical signs of Organophosphates toxicity? (6)

salivation, lacrimation, urination, defecation, miosis, and bradycardia

How do you diagnose organophosphate toxicity?

cholinesterase levels

What is the treatment for Organophosphates toxicity?

2-PAM (Pralidoxime) will disrupt OP-ACHase bonds that are not aged

What is the prognosis for organophosphate toxicity?

guarded

What is the pathogenesis behind Pyrethrins & Permethrins toxicity?

Sodium channel facilitation, GABA channel blocked

What are the clinical signs of Pyrethrins & Permethrins toxicity? (5)

Tremors, ataxia, salivation, seizures, dyspnea

T/F Pyrethrins & Permethrins toxicity is more common in cats than dogs

true

What are the TWO ways that you can diagnose Pyrethrins & Permethrins toxicity?

§ Test for chemical residue on hair (takes days)

§ Post-mortem testing of liver and fat available

What is the THREE things you can do for treatment Pyrethrins & Permethrins toxicity?

What is the prognosis for this toxicity?

§ Decontamination of skin

§ Diazepam for seizures in emergency setting

§ Methocarbamol for tremors

Guarded to good

What is the pathogenesis of Bromethalin?

Blocks electron transport chain = energy deprivation = brain cell edema= increase ICP

What are the clinical signs of acute Bromethalin toxicity? (3)

Seizures, tremors, excitation

What are the clinical signs of chronic Bromethalin toxicity? (5)

Ataxia, obtundation-coma, tremors, extensor rigidity, seizures

How do you diagnose Bromethalin toxicity?

Detected in frozen fat, liver, kidney, and brain

How can you treat Bromethalin toxicity?

§ Emesis

§ Charcoal (q6h for 48h) and cathartic (with 1st dose)

§ Methocarbamol for tremors

§ Mannitol may ¯ ICP +/- corticosteroids

§ Anti-epileptics to control seizures

What is the pathogenesis of Strychnine toxicity?

Glycine antagonism at sites in spinal cord and brain

T/F Glycine is an excitatory neurotransmitter

False, inhibitory

What are the clinical signs of Strychnine toxicity? (4)

Seizures, tremors, opisthotonus, extensor rigidity

What causes death in Strychnine toxicity?

exhaustion of respiratory muscles

How do you diagnose Strychnine toxicity?

Liver and kidney samples will contain the toxin

How do you treat Strychnine toxicity?

§ Emesis

§ GI decontamination with charcoal

§ Anti-convulsants

§ Muscle relaxants

§ Fluid diuresis due to renal elimination

T/F The pathogenesis behind Metaldehyde toxicity is unknown

True

How do you diagnose Metaldehyde toxcity?

frozen stomach contents

How do you treat Metaldehyde toxicity?

§ Emesis

§ Gastric lavage and charcoal to decontaminate

§ Methocarbamol for controlling tremors

§ Fluid therapy often needed to reduce acidosis

§ Anti-convulsants

You have a dog that came in two weeks ago for diarrhea. You do a fecal and the dog has giardia. The dog is now back because it has Acute central vestibular disease.

How did the dog get this diseae?

Metronidazole toxicity

What is the treatment of Metronidazole toxicity?

§ Symptomatic treatment

§ Initial IV diazepam bolus at 0.5 mg/kg

§ Follow with diazepam 0.5 mg/kg PO TID for 3 days OR consider IV CRI

What are some ways that cause primary injury due to truma?

mechanical insult, hemorrhage

What are some ways that trauma can cause secondary injury?

§ Oxidative stress

§ Excessive excitatory neurotransmitter release

§ Vascular occlusion

§ Activation of inflammatory mechanisms

§ Catecholamine release

What can trauma lead to that can cause CSF and blood to be displaced?

increased intracranial pressure

T/F Once compensation is surpassed, ICP will quickly rise

True

What are TWO things that high ICP can cause?

Cerebral perfusion decreased, Brain herniation

What is the equation for Cerebral perfusion pressure (CPP)?

Cerebral perfusion pressure (CPP) = Mean arterial

pressure (MAP) – ICP

T/F An increase in ICP means a increase in CPP

Fasle, they're inversely related

What is the pathogenesis behind the Cushing's Reflex?

CPP drops → ischemia in the brain = sympathetic surge

from hypothalamus → massive catecholamine release →

systemic hypertension → peripheral baroreceptor

stimulation → vagal stimulation → bradycardia

Modified Glasgow Coma Scale Score (MGCS) is what brain injury is based on. A category I has a ___ prognosis a score _ has 50% survival at 48 hours

grave, 8

Modified Glasgow Coma Scale Score (MGCS) is what brain injury is based on. Category __ (>___score) >90% chance for 48 hour survival

III, 14

What is an osmotic diuretic moves fluid from EV spaces into IV spaces thus decreasing volume of the brain?

Mannitol

What are THREE cases when you should use mannitol?

• Evidence of brainstem dysfunction

• Decline in MGCS score

• Cushing's reflex

T/F You should not give mannitol to a dehydrated, renal or cardiac, or hypotensive

True

What is the rate of hypertonic saline used for treatment?

2-5 ml/kg over a 3-5 min

How dies Hyperventilation decrease ICP?

by decreasing CO2 levels

When should you do a Craniotomy/Durotomy?

• Intracranial hemorrhage or significant cerebral edema

• Lower ICP

• Remove compressive bone fragments +/- extra-axial hematomas

T/F Barbiturates increase ICP

False, decreases

What drugs used to be used alot to treat brain trauma but have no benefits were seen in coma scale scores?

Corticosteroids

What are the TWO things that cerebrovascular disease can lead to and what are their sequeles?

Vessel Occlusion- Ischaemic Stroke

Vessel Rupture: Haemorrhagic Stroke

What intracrainial disease is seen with a reduction in blood flow due to underlying disease?

Ischemic Stroke

What are NINE things that can lead to Ischemic Stroke?

- Cardiovascular

- Infectious - vasculitis

- Larval migrans § Neoplasia

- Hypercoagulable state: Hyperadrenocorticism, Renal failure

- Increased blood viscosity, Hypercholesterolemia, polycythemia vera

- Hypothyroidism

- Systemic hypertensio

- Hypoxia under anesthesia (global

What classification of Ischemic Stroke involves entire territory of 1 major artery?

Territorial

What classification of Ischemic Stroke obstruction of smaller artery?

lacunar

What classification of Ischemic Stroke has global ischemia at boundary between 2 major artery territories

Watershed

What are the clinical signs of Ischemic Stroke? (2)

- Peracute to acute in onset and reflect lateralized/focal brain dysfunction

- Cerebellum predilection site

What is the first thing you should do when trying to diagnose Ischemic Stroke?

Examples?

Investigate for underlying causes

o CBC/Chemistry/UA

o Endocrine Testing '

o Infectious disease titers

o Thoracic radiographs

o Abdominal ultrasound

o ECG, echocardiogram, blood pressure

What is the best modality for identifying ischemic infarcts?

MRI

T/F CSF may or may not show evidence of inflammation

True

How do you treat Ischemic Stroke?

• Treat underlying etiologies

• Supportive care

What is the prognosis for Ischemic Stroke in animals with underlying causes?

• Grave - likely to have more events

What is the prognosis in animals with idiopathic events?

Good to guarded

What intracranial disease is caused by hemorrhage due to underlying diseases?

Hemorrhagic Stroke

What are FOUR causes of Hemorrhagic Stroke?

-Systemic hypertension

-Coagulopathy

-Neoplasia

- Vascular defects

How do you diagnose Hemorrhagic Stroke?

Coagulation panel

How do you treat Hemorrhagic Stroke?

-Treat underlying cause

- Supportive care

What is the prognosis with Hemorrhagic Stroke?

guarded to good