THEMIMICSofSEIZUREACTIVITY · 2014-08-04 · THEMIMICSofSEIZUREACTIVITY Simon R. Platt BVM&S MRCVS Diplomate ACVIM (Neurology) Diplomate ECVN College of Veterinary Medicine, The University

THE MIMICS of SEIZURE ACTIVITY

Simon R. Platt BVM&S MRCVS Diplomate ACVIM (Neurology) Diplomate ECVN

College of Veterinary Medicine, The University of Georgia

Introduc7on

•  Seizure ac7vity may only be seen by owner

•  Seizure ac7vity localizes to forebrain

•  Forebrain disease dictates specific CNS work up

•  Similar events may require different inves7ga7ons

•  Mimics non-‐responsive to an7convulsants

What is a Seizure?

•  Peracute •  Unexpected onset and offset

•  Stereotypical –  Involuntary motor ac7vity

–  Increased muscle tone –  +-‐ abnormal menta7on –  +-‐ autonomic signs

Paroxysmal Events that Mimic Seizures

•  Syncope •  Narcolepsy / cataplexy • Movement disorders •  Neuromuscular Disorders •  Behavior disorders •  Sleep Disorders • Myoclonus •  Tremor syndromes •  Painful focus

Event Type Precipita/ng Event

Consciousness? Flaccid or Spas/c?

A;er Event

Seizure Nothing Not if Generalized

Spas7c Confused / blind?

Syncope Exercise, ac7vity Reduced to absent

Flaccid Normal

Narcolepsy / Cataplexy

Excitement, feeding

Absent Flaccid Normal

Event Type Precipita/ng Event

Consciousness? Flaccid or Spas/c?

A;er Event

Movement Disorder

None to excitement / ac7vity

Normal OYen spas7c Normal

Sleep Disorder Sleep Reduced to absent

Either Confused

Neuromuscular Collapse

Ac7vity Normal Flaccid Normal

•  Abrupt and transient loss of consciousness accompanied by loss of muscular tone.

•  Caused by a sudden, global reduc7on in cerebral perfusion

•  S7ffening of the limbs, opisthotonic posture, micturi7on, and vocaliza7on are common!

•  Acutely reduced cardiac output, ou\low obstruc7on, hypoxia or decreased vascular resistance related to neurocardiogenic reflexes.

•  Requires cardiac work up / Holter monitor

Syncope

Movement Disorders

•  New field of neurology •  Involuntary movement •  Mostly present during inac7vity

•  No loss of consciousness •  Func7onal abnormality of the nervous system

•  OYen breed related •  Can be local vs. generalised

Clinical Sign or Syndrome Defini/on

Cramp Muscle cramps are involuntarily and forcibly contracted muscles that do not relax

Dyskinesia Difficulty or distor7on in performing voluntary movements

Myotonia Sustained muscular contrac7on following an ini7a7ng s7mulus

Myoclonus Rhythmic movement of a por7on of the body resul7ng from sudden involuntary contrac7on and relaxa7on of muscle groups

Spasm A brief, automa7c jerking movement

Tetanus Sustained muscular contrac7on without a period of relaxa7on

Tremor Any abnormal repe77ve shaking movement of the body

Myoclonus

•  Shock like contrac7on of muscle

•  Repeatedly rhythmic flexion extension of large groups of muscles

•  Persistent during sleep •  Focal or generalized •  Limbs / facial muscles •  OYen due to distemper in dogs

Tremor •  Most common movement

disorder •  Fixed frequency

synchronous contrac7ons of muscles

•  Focal or generalized •  Stop with sleep •  Physiological, idiopathic

(essen7al eg senile) or pathological

•  Lesion anywhere in CNS or PNS

Myotonia •  Prolonged contrac7on or delayed

relaxa7on of a muscle •  Follows movement or s7mula7on •  Due to decreased chloride

conductance •  Congenital in Chow/Min.

Schnauzer / Australian Cacle dog / Jack Russell

•  Muscle dimpling seen on palpa7on

•  Treat with procainamide / phenytoin or mexili7ne

Paroxysmal Dyskinesia •  Impaired power of voluntary

movement •  Fragmented or incomplete

movement •  Abnormal posture

–  Hold up limb –  Kypho7c posture

•  Appear as ‘cramps’ during ac7vity or rest

•  Increased muscle tone •  Collapse •  Check for breed associa7on •  Described in associa7on with

PB and propofol

Movement Disorder

(1) Scoie Cramp •  < 3yrs old •  Stress, excitement or

exercise •  Thoracic limbs ini7ally

affected •  Arched spine; pelvic limb

s7ffness •  Resolves in 10 minutes •  Autosomal recessive •  Deficiency of serotonin? •  Induced 2hr aYer

methylsergide with exercise •  SSRIs and ACP treatment

(2)Episodic Hypertonicity in Cavaliers

•  Episodic falling syndrome •  UK, USA, Australia •  Autosomal recessive

chromosome 7 •  13% of breed are carriers •  Brevican gene dele7on •  Gene7c test available •  3-‐7 months old but can be

upto 4yrs •  Normal otherwise

(2) Episodic Hypertonicity in Cavaliers

•  Variable periods of exercise induce events

•  ‘Bounding’ pelvic limb gait •  Progress to bunny hopping, arching of spine and collapse

•  No loss of consciousness •  Normal on work up •  Treat with clonazepam? •  Treat with acetazolamide?

(3) Border Terrier Cramping Syndrome •  Canine Epileptoid Cramping syndrome /

Spike disease •  Paroxysmal dystonic choreoathetosis /

non-‐kinesigenic dyskeniesia •  Most <3 yr old •  No gender prediposi7on •  2-‐30 mins long (0.5-‐150 mins) •  Not preciputated by ac7vity or sleep •  Difficulty in walking / mild tremor /

dystonia •  All four limbs and head and neck

affected •  Associated GI signs / skin disease / food

intolerance •  May respond to dietary changes – Hills

k/d?

(4) Paroxysmal Dyskinesia in Chinooks

•  Inability to stand or ambulate

•  Head tremors •  Involuntary flexion of 1 or mul7ple limbs

•  10 mins to hour long •  Autosomal recessive •  No treatment known

(5) Startle Disease in Irish Woltounds

•  Hyperekplexia •  Noise or touch induced •  Muscle s7ffness and

apnea •  Generalized tremor •  Defec7ve inhibitory

(glycine) transmission •  Microdele7on in the gene

encoding a presynap7c glycine transporter

•  1 week – 3 months old •  Blood test available

(6) Lafora’s Disease in Miniature Wirehaired Dachshunds

•  Familial Mycolonic epilepsy

•  Repe77ve muscle contrac7ons in response to visual, auditory or tac7le s7mula7on

•  6-‐13 yrs old •  Muta7on of EPM2B gene for protein MALIN

•  Muscle biopsy!

(6) Lafora’s Disease in Miniature Wirehaired Dachshunds

•  Familial Mycolonic epilepsy

•  Repe77ve muscle contrac7ons in response to visual, auditory or tac7le s7mula7on

•  6-‐13 yrs old •  Muta7on of EPM2B gene for protein MALIN

•  Muscle biopsy!

(7) Dancing Doberman Disease

•  Intermicent flexion of one or both pelvic limbs

•  Muscle atrophy and weakness may be seen

•  Gastrocnemius mm or scia7c nerve disease

•  Axonal disease on biopsy •  No known treatment

(8) Generalized Muscle S7ffness in Male Labrador Retrievers

•  2-‐41 months old (mean onset 17 months)

•  Stabilizes in adulthood •  Pelvic limb to thoracic limb

progression •  Generalized muscle s7ffness •  Persists at rest •  Flexed posture &

bradykinesia •  Possibly X-‐linked disorder •  No treatment (NSAIDs?)

Head Bobbing

•  Idiopathic head tremor •  Postural repe77ve myoclonus -‐Stretch reflex mechanism?

•  Dobermans, Boxers, Bulldogs & others

•  Familial in young dogs (<1yr)

•  Median 2y in E Bulldogs •  No gender influence

Head Bobbing

•  Yes or no tremors – 5-‐6Hz •  Intermicent •  Median dura7on 3 mins •  Responsive and Conscious •  At rest / stops when ac7ve and

when distracted •  Dogs normal but triggers exist •  Lesions of thalamus and

cerebellum can cause •  No treatment •  Can resolve (49% E Bulldogs)

Orthosta7c Tremors

•  Young Great Danes and Scoish Deerhounds

•  Postural tremor •  Only when weight bearing •  Absent when lying down •  13-‐16Hz ac7on poten7als •  May respond to gabapen7n

Neuromuscular Collapse •  Ac7vity associated

weakness •  Could have normal

neurological exam –  Ventroflexion of neck –  Short choppy gait –  Over flexion of joints –  Plan7grade stance –  Muscle atrophy –  Decreased muscle tone –  Decreased reflexes

DNM1-‐Exercise Induced Collapse •  Labrador retrievers /

Chesapeake Bay retrievers / Curly coated retrievers /Border collies?

•  Autosomal recessive •  84% affected by 4yrs old

–  Mean onset 17mo •  S7mulated by 5-‐20 mins

intense exercise + excitement •  Ataxia to flaccid paraparesis

(loss of patella reflex) •  Hyperthermia normal but may

contribute •  Recovery in <30 mins Courtesy Susan Taylor

DNM1-‐Exercise Induced Collapse •  Dynamin 1 -‐ point muta7on in

exon 6 •  DNM-‐1 important in synap7c

vesicle recycling •  Subs7tu7on of arginine by

leucine •  Diagnose with DNA tes7ng •  1.8-‐13% homzygous Lab Rets /

17-‐37.6% carriers •  Prevalence depends on func7on

of dog •  Reduce ac7vity for Tx

Courtesy Susan Taylor

Feline Hyperesthesia Syndrome •  Episodic behavioral twitching and

fascicula7on •  OYen in response to s7mula7on •  Cats become agitated and

aggressive •  Frenzied licking, bi7ng, running •  Dilated pupils / hallucina7ons? •  Lasts 1-‐5 mins •  Local dz vs. seizure vs. behavior? •  Treat with an7-‐inflammatories /

an7convulsants or SSRIs

Feline Hyperesthesia Syndrome •  Episodic behavioral twitching and

fascicula7on •  OYen in response to s7mula7on •  Cats become agitated and

aggressive •  Frenzied licking, bi7ng, running •  Dilated pupils / hallucina7ons? •  Lasts 1-‐5 mins •  Local dz vs. seizure vs. behavior? •  Treat with an7-‐inflammatories /

an7convulsants or SSRIs

Narcolepsy / Cataplexy •  Narcolepsy = disorder of sleep wake

control •  Cataplexy = disorder of muscle tone •  Familial, inherited or acquired •  Dobermans, Labradors, Min.

Poodles, Beagle, Dachshund •  Autosomal recessive with full

penetrance in Dobermans and Labradors

•  Chromosome 12 – canarc-‐1 gene •  Collapse with REM sleep •  Induced by excitement •  Seen in first 6 mo of life

Narcolepsy / Cataplexy •  Neurotransmicer abnormality •  Hyocre7ns / orexins –

hypothalmic neuropep7des (Hcrt-‐1 & 2)

•  Secre7on increases when awake; decreases when asleep

•  Receptor deficiency if inherited •  Autoimmunity?

•  Signs alleviated using imipramine and or atropine IV

•  Tx with imipramine & methylphenidate

REM Sleep Disorders

•  2 stages of sleep – non-‐REM and REM –  Non-‐REM sleep = decreased body temperature, heart rate and respiratory rate but normal muscle tone

–  REM sleep = increased body temperature, heart rate and respira7on with atonia and eye movements

REM Sleep Disorders •  Some movement is normal

during REM sleep •  Brainstem normally inhibits

LMN cells in spine •  Violent limb movements,

howling, barking, growling, chewing, bi7ng

•  Can be woken up •  30% of dogs = Golden rets. •  64% < 1 yr old (2mo-‐7.5 yrs) •  Confirma7on requires EMG and

EEG •  Treatment with potassium

bromide reduces events in 80%

Compulsive Behavior Disorders

•  Stereotypies = repe77ve unvarying behavior pacerns with no goal or func7on

•  CD is Similar to OCD in people –  Hand washing –  Arranging items –  Checking –  Rituals

•  Different neurotransmicer systems implicated –  opioid-‐mediated –  dopaminergic –  serotonergic, –  Glutamatergic


•  In dogs and cats: –  Locomotor –  Oral –  Aggression –  Vocaliza7on –  Hallucinatory


•  Locomotor – circling, tail chasing, chasing lights

•  Oral – foot or flank licking, air licking, nose licking

•  Aggression – self directed, acacking inanimate objects

•  Vocaliza7on – rhythmic barking or whining

•  Hallucinatory – startling, chase shadows or lights


CAUSES: 1.  Stress – conflict behavior 2.  Genotype – gene7c

predisposi7on ie flank sucking in Dobermans / spinning in Bull Terriers / checking hind end in Min. Schnauzers

3.  Medical problems 4.  Condi7oning

QUESTIONS?

THEMIMICSofSEIZUREACTIVITY · 2014-08-04 · THEMIMICSofSEIZUREACTIVITY Simon R. Platt BVM&S MRCVS Diplomate ACVIM (Neurology) Diplomate ECVN College of Veterinary Medicine, The University

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