Submitted by :Dr. Akhilesh

Division of Medicine,

SEIZURES

Definition• Seizure

It is a condition where there is paraoxysmal, self limited functional cerebral disturbances characterized by abnormal electrical activity of brain leading to the overt signs known as “seizures”, “epilepsy”, “fits” or “convulsion”.

Each attack is characterized by sudden loss of consciousness.

Seizure and Epilepsy• A seizure is a brief, temporary

disturbance in the electrical activity of the brain.

• Epilepsy is a disorder characterized by recurring seizures (also known as “seizure disorder”)

• A seizure is a symptom of epilepsy.

Epilepsy State of recurrent seizures regardless

of aetiology

Primary epilepsy (functional, asymptomatic): is result of functional cerebral disturbances for which there is no underlying cause other than hereditary disposition e.g. canine idiopathic epilepsy.

Secondary epilepsy (structural, symptomatic)caused by acquired brain lesions e.g. posttraumatic

Causes

1. Extracranial• Hypoglycemia• Hypocalcaemia• Hepatic/renal

encephalopathy• Hypoxia• Toxicity

2. Intracranial• Inflammation• Neoplasm• Malformation• Traumas• Hydrocephalus• CD• ICH

Pathophysiology• Imbalance of number of positive and

negative ions between inside and outside of cell membrane

• Due to change in resting membrane potential

• Disturbance in sodium pump and• Increased availability of excitatory

neurotransmitter leads to seizure

Nomenclature• Status epilepticus is the term used to

describe– A seizure lasting longer than 15 minutes, or– A collection of discrete seizures without full

recovery of consciousness

• Cluster seizures occur when 2 or more seizures are experienced in a brief periods, but the patient regains consciousness between them

• Jacksonian seizure is a partial seizure which begins in one group of muscles and spreads to adjacent muscle groups in the same limb and then to the ipsilateral limb

Generalised seizures Focal seizures

CLASSIFICATION OF SEIZURES

I. Generalised Seizures (Grand mal)

1.Idiopathic2.Symptomatic

• Due to intracranial disease e.g. neoplasia, storage diseases etc.

3.Cryptogenic• There is probably an underlying

cause but it cannot be identified by the diagnostic tests available.

4.Reactive• Due to some extracranial disorder,

for example a toxin or metabolic disorder

Generalized seizures• Absence seizures, appear to be staring into

space These seizures are sometimes referred to as petit mal seizures, which is an older term.

• Tonic seizures cause stiffening of muscles of the body

• Clonic seizures cause repeated jerking movements of muscles on both sides of the body

• Myoclonic seizures cause jerks or twitches of the upper body, arms, or legs.

• Atonic seizures cause a loss of normal muscle tone - will fall down or may drop head involuntarily.

• Tonic-clonic seizures cause a mixture of symptoms, older term: grand mal seizures

Stages

1. Prodromal Phase– The animal experiences an indication of a

forthcoming seizure.– This occurs hours to days before the event

itself.2. Aural Phase

– This is the very start of the seizure.– Behaviour changes may be apparent.

3. Ictal Phase– The seizure "proper".

4. Postictal phase– Consists of transient neurological and

behaviour changes, which can last from hours to days.

II. Focal or partial Seizures• Focal or assymmetrical sensory or motor

activity affecting any part of the body E.g. facial twitching, champing of mouth

• Can be associated with autonomic signs e.g. salivation, vomiting

• Almost always an acquired disease

• Can spread to involve whole cortex and become a generalized seizure

• Simple focal motor seizure

• Remain conscious - sudden focal jerking of a muscle group

• Complex focal seizure

• Change in or loss of consciousness. dreamlike experience.

• may display strange, repetitious behaviours (automatisms) such as blinks, twitches, mouth movements, walking in a circle.

Investigation of Seizures

• It must first be determined whether seizure activity is in fact a seizure, rather than a non-epileptic paroxysmal event, for example:– Syncope– Exercise-induced weakness– Obsessive-compulsive behaviour– Narcolepsy

History Seizure type: partial suggest focal, structural,

intracranial lesion Age:

Tumour Drugs Episodic behavioral abnormalities are suggestive of

extracranial metabolic disorders Toxins: any age group

0-1 yr Hypoglycemia, portosystemic shunt, encephalitis, hydrocephalus

1-5 yr Idiopathic epilepsy5 yr + Neoplasia, hypoglycemia(insulinoma)

Examination Persistant interictal neurological

abnormalities e.g. circling, proprioceptive deficits, blindness are suggestive of structural intracranial lesion

Active occular lesion in infectious diseases e.g. distemper

Cardiac abnormalities e.g. arrythmia may result in hypoxic seizures

Neoplasia detected on physical examination raises possibility of metastatic disease.

HA

EM

ATO

LOG

Y Leukocyte

abnormality may suggest inflammatory process

Distemper virus inclusions in neutrophils

BIO

CH

EM

ISTR

Y Glucose levels

Cholesterol, urea, bilirubin, albumin = hepatic functionSerum bile acid levels( preprandial and 2 hr post prandial) are best liver function testElectrolyte levels

IMM

UN

OLO

GYSerology for

distemper, toxoplasma

Immunoflorescence of conjunctival scrappings for distemper antigen

LABORATORY DIAGNOSIS

PH

YS

ICA

L P

RO

CE

DU

RE

S ECG

CSF analysis

DIA

GN

OS

TIC

IMA

GIN

G CT or MRI (no extracranial

cause)

USG (portosystemic shunts)

Nuclear scintigraphy(confirm shunt presence and quantify its magnitude)

Radiographs (neoplasia)

Portal venography (portosystemic shunt anatomy)

When/Why to Start Treatment???

More than 1 seizure in a 4-6 week periodActive intracranial disease (neoplasia, inflammation)Cluster seizuresStatus epilepticus

Drugs Used for Treatment of Status Epilepticus

Seizure Treatment

1. Anticonvulsants• Dogs

– Monotherapy• Phenobarbital• Diazepam

– 2nd line drugs• Bromide• Phenobarbital• Gabapentin• Zonisamide• Levetiracetam

– 3rd line drugs• Clorazepate• Felbamate

Seizure Treatment

Anticonvulsants• Cats

– Monotherapy• phenobarbital

– Ancillary drugs• Diazepam• Bromide• Not much information on other

ancillary drugs

Drug Species and DosageDiazepam Dogs, cats 0.5–2.0 mg/kg, IV bolus; can be repeated 2–3 times at

intervals of 5–10 min; CRIa 0.5–2.0 mg/kg/hr

Foals: 0.05–0.4 mg/kg, IV slowly

Adult horses: 25–50 mg/horse, IV

Ruminants: 0.5–1.5 mg/kg, IV or IM

Phenobarbital Dogs, cats: 2–4 mg/kg/ IV bolus; can be repeated at 20- to 30-min intervals until a total dosage of 20 mg/kg is reached; CRI 3–10 mg/hr to effect

Foals, adult horses: loading dose of 12–20 mg/kg, IV over 20 min, then 6.65–9 mg/kg, IV over 20 min every 8–12h

Sodium pentobarbital

Dogs, cats: 2–15 mg/kg, IV, to effect to stop motor activity

Foals, adult horses: 2–4 mg/kg, IV to effect

Propofol Dogs, cats: 2.5–4.0 mg/kg, IV, to effect to stop motor activity; CRI: 0.1–0.3 mg/kg/min to effect

Phenytoin Dogs 2–5 mg/kg as slow IV infusion

Foals, adult horses: 5–10 mg/kg, IV followed by 1–5 mg/kg, IV, IM, or PO every 2–4 hr until seizures stop and maintenance dose started

Seizure Treatment

Emergency TreatmentEmergency Anticonvulsants• Diazepam • Phenobarbital• Propofol• Pentobarbital• Boluses or CRI

Seizure Treatment

Diazepam Half life

– 2-4 hours in dogs– Long enough for maintenance in cats– But can cause hepatic necrosis in cats

• Boluses IV or per rectum– 0.5-1 mg/kg IV (1-2cc per 20 lbs)– Up to 3 boluses– Owners can do per rectum at home

• Continuous infusion if boluses not effective– 0.5-2 mg/kg/hr in D5W or 0.9% NaCl– Add 7.5-30cc diazepam to 150 ml fluids – Administer at 1 ml/lb/hr

Seizure Treatment

Phenobarbital• 1-3 mg/kg IV bolus

– Up to 15-20 minutes for full effect– Usually causes ataxia

• CRI if bolus not effective– 2-4 mg/kg/hr in D5W or 0.9% NaCl– Monitor for cardiopulmonary depression

PhenobarbitalDose (a) Dog - 2 - 4 mg/kg every 12

hours

(b) Cat – 1.5 - 2.5 mg/kg every 12 hours

Therapeutic serum concentration (a) Dog - 15 - 40 µg / ml

(b) Cats - 23.2 - 30.2 µg / ml

Seizure Treatment

Propofol • 1-2 mg/kg IV bolus

– Intubate if needed– Assist ventilation if apneic

• Anti-seizure CRI if bolus not effective– 0.1-0.6 mg/kg/hr in D5W or 0.9% NaCl

• Anesthesia CRI if above not effective– Up to 6 mg/kg IV (<3 cc per 10 lb) to effect – The CRI 6 mg/kg/hr– Monitor for cardiopulmonary depression

Seizure Treatment

Pentobarbital• 2-15 mg/kg IV bolus

– Give slowly over several minutes to effect– Intubate

• CRI if bolus not effective– 0.5-4 mg/kg/hr in D5W or 0.9% NaCl– Monitor carefully for cardiopulmonary

depression– Dysphoria and paddling is common– Difficult to distinguish form seizure

Protocol for status epilepticus seizure management1. 2 ml / kg 50% dextrose IV2. 10% calcium gluconate, 4 ml /kg IV slowly3. Inj Diazepam 0.5 mg/kg IV repeated at 10 min

interval upto 3 times4. Inj. Pentobarbitone @ 3-16 mg /kg IV or

phenobarbitone 2-4 mg/kg IV.5. Infuse Midazolam in 5% dextrose or normal saline

at 0.5 to 2 mg / kg/ hour into fluids 6. General anesthesia7. Lorazepam, Clonazepam – long acting single 2.5

– 10 mg IV effective for 12-24 hours 8. Supplement phenytoin 1-3 mg/ kg /hour

Emergency Seizure Protocol

1. Stop the Seizure2. Provide supportive care3. Prevent further seizures

Emergency Seizure Protocol

1. Stop the Seizure• Up to 3 diazepam boluses

• This will last up to 30 minutes• If no effect, phenobarbital bolus• If no effect, propofol low dose bolus• If no effect, induce anesthesia

• Isoflurane• Propofol CRI• Pentobarbital bolus or CRI

Emergency Seizure Protocol

2. Provide Supportive Care• oxygen

• By face mask if conscious• By tube if intubated

• IV fluids – place catheter• 1 ml/lb per hour for maintenance• Less if CHF• More if dehydrated or shocky

• Monitor temperature• Cool if needed• Warm with time (anticonvulsant therapy

can drop temp)

Emergency Seizure Protocol

3. Prevent further seizures• Start PO phenobarbital 1-3 mg/kg

• if not already given as a bolus• If conscious enough to swallow• Can give IM if can’t swallow

• If on anticonvulsants, consider starting new drug• Bromide can be given rectally if can’t

swallow• May cause transient diarrhea

Seizure Treatment

Client Education• Medications must be given daily, for life• Explain side effects & drug interactions

(handouts)• Missed dose should be given as soon as

remembered, then back on schedule with next dose

• Owner seizure log – date, time, description, duration

• Dose determined over time by blood tests• Dose may increase or decrease over time• Drugs will not reach full effect for weeks to

months• Initial side effects often subside with time

Thank you