Febrile Seizures

Amy Kao, MD

2005-2006

Division of Pediatric Neurology

Oregon Health & Science University

Stirred, Not ShakenGetting Comfortable with Neurology

Learning Objectives

• Review basic definitions and classification of seizures

• Discuss the specific epilepsy syndrome of febrile seizures

• Review the neurologic exam in the context of the concept of anatomical localization of neurologic symptoms and deficits

The Basics

• Definition of a Seizure

sudden event caused by abrupt, uncontrolled, hypersynchronous discharges of neurons

More Definitions

• Epilepsy

– condition characterized by the tendency for recurrent seizures that are unprovoked by an immediate cause

• Status epilepticus

– > 30 minutes long OR

– Back-to-back without return to baseline

Seizures—Differential Dx

• Loss of tone or consciousness– Abnormal heart rhythm– Vasovagal syncope (classic fainting)– Attention deficit disorder

• Disorders of breathing– Breathholding spells– Hyperventilation

• Other medical disorders– Hypoglycemia– Gastroesophageal reflux

Seizures—Differential Dx (2)• Unusual” movements

– Benign sleep myoclonus– Shuddering attacks– Migraine (torticollis, ataxia, confusional)– Tics– “Pseudoseizures”

• Behavioral or Self-stimulation– Night terrors– Sleep walking– Rocking– Head banging– Infantile masturbation

Seizures—Etiology• V(ascular): AVM, stroke, hemorrhage, HTN• I(nfectious): meningitis, encephalitis• T(raumatic)• A(utoimmune): SLE, vasculitis, ADEM• M(etabolic/toxic): electrolyte imbalance, tox• I(diopathic): “idiopathic epilepsy”• N(eoplastic)• S(tructural): cortical malformation, prior

stroke, “other causes of CP”• S(yndrome): genetic disorder

Classification of Seizures By Onset

• Generalized– Begins simultaneously in both

hemispheres– Generalized-tonic-clonic = “grand-mal”– Absence = “petit-mal”– Myoclonic– Tonic– Atonic

Classification by Onset, continued

• Partial (=Focal)

– Onset in a focal region of the brain

– Simple partial

– Complex partial

– Secondarily generalized

Classification of Seizures By Cause

• Acute Symptomatic

– Shortly after an acute insult

• Infection

• Hypoglycemia, low sodium, low calcium

• Head trauma

• Toxic ingestion

Classification by Etiology, continued

• Remote Symptomatic

– Pre-existing brain abnormality or insult• Brain injury (head trauma, low oxygen)• Meningitis• Stroke• Tumor• Developmental brain abnormality

Classification by Etiology, continued

• Idiopathic

– No history of preceding insult

– Likely “genetic” component

Classification by Syndromes

• Definition of a syndrome

– Cluster of symptoms, signs, and lab findings (EEG)

– Consistent

– Implies diagnosis, treatment, or prognosis

• There are syndromes specific to children

Febrile Seizures

• Definition

“a seizure in association with a febrile illness in the absence of a CNS infection or acute electrolyte imbalance in children older than 1 month of age without prior afebrile seizures”

Febrile Seizures

• Epidemiology

– 2 to 5 % of children in the US

– Most common form of childhood seizures

– Peak at 18 months

– Simple = isolated, brief, generalized

– Complex = focal, multiple, or prolonged

Simple Febrile Seizures• < 15 minutes• Generalized-tonic-clonic• Fever > 100.4 rectal to 101 F (38 to 38.4 C)• No recurrence in 24 hours• No post-ictal neuro abnormalities (e.g.

Todd’s paresis)• Most common 6 months to 5 years• Normal development• No CNS infection or prior afebrile seizures

Risk Factors for 1st Feb Sz

• Febrile seizure in 1st/2nd degree relative

• Day care

• Neonatal nursery stay of >30 days

• Developmental delay

• Height of temperature

Risk Factors for Recurrent FS

• 1/3 will have a recurrence

• 10% will have 3 or more

• FH of febrile seizures

• Age <18 months

• Height of temperature

• Duration of fever

Risk Factors for Epilepsy

• 2 to 10% will go on to have epilepsy

• Developmental delay

• Complex FS (possibly > 1 complex feature)– 5% > 30 mins => ¼ of all childhood status

• FH of epilepsy

• Duration of fever

Evaluation in Febrile Seizures

• Exclude acute etiologies

– HCT, lytes/cbc if history/PE suggests

– Strongly consider LP

• < 12 months old

• Prior antibiotic therapy

• Suspicious findings on history/PE

• Not absolutely necessary in > 18 mos

Evaluation in FS (2)

• EEG

– Does NOT predict recurrence or epilepsy

– More likely to be abnormal in:

• Older children

• Neurodevelopmental abnormalities

• Family history of febrile seizures

• Complex febrile seizure

Febrile Seizures—Treatment

• May reduce short-term recurrence

• But NO effect on occurrence of epilepsy

• AND the side effects !

• The approach is based on epidemiological data that FS are benign, so

• Prevent status epilepticus

FS—Treatment (2)

• Antipyretics– No data that this reduces risk– FS at onset of fever => highest recurrence

• Benzodiazepines– Rectal diazepam (Valium)

• 2-5 y/o 0.5 mg/kg• 6-11 y/o 0.3 mg/kg (round up to 2.5, 5, 10 mg)

– Oral diazepam • 0.33 mg/kg q8 hrs x 48 hrs during illness

FS—Treatment (3)

• Daily medications NOT recommended– Phenobarbital

• Drowsiness, sleep problems, hyperactivity, IQ

– Valproic acid• Hepatotoxicity

– Phenytoin and carbamazepine• Not effective

Seizures—Exam• Temp, BP, HC• Skin (rash, neurocutaneous lesions), Neck• Evidence of dysmorphisms, developmental delay• Evidence of increased intracranial pressure

– Bulging anterior fontanelle– Depressed level of consciousness– Pupillary asymmetries– Downgaze/sunsetting eyes– Abducens palsy– Papilledema

Seizures—Exam (2)

• Evidence of focal deficits– Weakness

• Intracranial lesion versus Todd paresis– Tone or reflex asymmetry

• ? Chronic versus acute

Seizures—Evaluation

• Lumbar puncture– “Strongly consider” in patient <12 mo with first

febrile seizure• Kernig’s, Brudzinski’s, nuchal rigidity low

sensitivity (Thomas 2002)

– But usually more than isolated seizure• History of irritability/lethargy• Complex febrile seizure• Slow postictal clearing of mentation

Seizures—Evaluation (2)

• Neuroimaging– “Emergent” HCT

• Concern of acute focal lesion, mass effect• I.e. persistent paresis or change in MS

– MRI (nonurgent)• Focal sz• Cognitive/motor impairment• Focal EEG findings

• EEG– Not if simple febrile seizure

Location, Location, Location

Overview of the Neuro Exam• Mental Status• Cranial Nerves• Motor• Gait• Coordination• Reflexes• Sensory• “General”

General

• Growth parameters (HC)

• Vital signs (temp, BP)

• Anterior fontanelle

• Flattening of the occiput

• Dysmorphic features

• Cardiac abnormalities

• Hepatosplenomegaly

• Cutaneous lesions

Mental Status

• Change in mental status = brain is not working correctly

• Level of consciousness– Lethargy– Stupor– Coma

• Attentive/interactive

• Language (receptive, expressive)

Cranial Nerves

• = Brain stem or nerve

• CN2 = optic nerve– Funduscopic exam– Visual fields/blink to threat– Visual acuity/color vision

• CN3, 4, 6 = oculomotor, trochlear, abducens– Eyelids– Pupils– Extraocular movements

Cranial Nerves (2)

• CN5 = trigeminal– Sensation– Masseter function– Corneal reflex (comatose or focal brain stem)

• CN7 = facial– Wide palpebral fissure and flat nasolabial fold– Both upper and lower face = LMN– Only lower face weak = UMN

Cranial Nerves (3)• CN8 = vestibulocochlear nerve

– Finger rub– Weber’s—louder ear = conduction deafness– Rinne—confirms above ear (air < bone)

• CN9, 10 = glossopharyngeal and vagus– Palate elevation, gag

• CN11 = spinal accessory– L SCM turns head to R, ear to ipsi clavicle

• CN12 = hypoglossal– Tongue in cheek

Motor• Hypotonia = LMN or UMN, cerebellum• Hypertonia = UMN lesion, basal ganglia

• Bulk/Fasciculations• Tone

– Resistance to passive ROM– Traction response, horizontal/vertical suspension

• Power– 0 to 5 grading scale– Techniques to bring out asymmetry

• Pronator drift, finger tapping, gait

Gait• Motor cortex, corticospinal tracts, basal

ganglia, cerebellum, vestibular system, nerves, muscles, vision, proprioception

• Good screening test• Natural gait• Toe walk, heel walk, tandem walk• Romberg (proprioception, vestibular)• Sit to stand

Coordination

• Limb ataxia = cerebellar hemispheres

• Gait ataxia = midline cerebellum

• Finger-to-nose testing/reaching for toys

• Rapid rhythmic alternating movements

• Titubation (truncal ataxia)

Reflexes

• Hyperreflexia = UMN lesion

• Hyporeflexia = LMN lesion

• 0 to 5+ grading scale

• Babinski’s sign = UMN lesion

• Correspond to spinal roots

• Primitive reflexes

Sensation

• Stocking-glove = nerve• Vibration/proprioception = dorsal columns• Pain/temp = spinothalamic tracts• Extinction = cortex

• Localization of stim• Purposeful withdrawal to painful stim• Spinal level

Questions re:Neuro Exam?

http://medstat.med.utah.edu/pedineurologicexam/home_exam.html

Bibliography

• Baumann RJ and Duffner PK. Treatment of children with simple febrile seizures: The AAP practice parameter. Pediatr Neurol 2000;23:11-17.

• Hirtz D et al. Practice parameter:evaluating a first nonfebrile seizure in children. Neurology 2000;55:616.

• Knudsen FU. Febrile seizures: Treatment and prognosis. Epilepsia 2000;41:2-9.

• Prensky AL. An approach to the child with paroxysmal phenomena with emphasis on nonepileptic disorders. In: Pellock JM, ed. Pediatric epilepsy diagnosis and therapy. New York: Demos Medical Publishing, 2001:97.

Bibliography

• Provisional committee on quality improvement, subcommittee on febrile seizures. Practice parameter: the neurodiagnostic evaluation of the child with a first simple febrile seizure. Pediatrics 1996;97:769.

• Shinnar S and Glauser TA. Febrile seizures. J Child Neurol 2002;17:S44-52.

• Thomas KE et al. The diagnostic accuracy of Kernig’s sign, Brudzinski’s sign, and nuchal rigidity in adults with suspected meningitis. Clin Inf Dis 2002;35:46.

• Warden CR et al. Evaluation and management of febrile seizures in the out-of-hospital and emergency department settings. Ann Emerg Med 2003;41:215.