Lead Poisoning and SeizuresDayna Ryan, PT, DPTWinter 2012

OverviewNormal blood lead level is 0Toxicity is not evident until blood lead levels build up over months or yearsToxic threshold is lower in children & pregnant womenHigh levels can be fatal

Lesion SiteCNS or PNSIn children: brain (encephalopathy with scattered hemorrhages)In adults: peripheral myelin or axon (peripheral neuropathy)Lead Poisoning

EtiologyIn children: lead-based paint in old building (prior to 1978)Contaminated air, water, soil, toys, glazed dishware, imported canned food, cosmetics

OnsetAfter months of exposure unless large amountFaster absorption with inhalation Lead Poisoning

Signs & Symptoms

Muscle weakness that can progress to paralysisaffect UEs more, cause wrist dropAtrophy of musclesTremorAbnormal DTRs (CNS lesion , PNS lesion)Chronic exposure in childrenMental retardation, learning disabilitiesHyperactivity, behavior problemsLoss of appetite, vomiting, abdominal painUnusual paleness from anemiaSluggishness, fatigueFasciculations (twitches)

DiagnosisBlood testSlowed motor NCVsFibrillation potential on EMG

Prognosis depending onLength & level of lead exposureWhether myelin (initial exposure) or axon (prolonged exposure) is damaged

TreatmentsRemove the source!Chelating agents to bind the lead so that it's excreted in the urine

Lead Poisoning

Epilepsy / SeizureElectrical storm in the brainEpilepsy Chronic disorder characterized by recurrent episodes of seizures due to excessive discharge of cerebral neurons

Seizure Involuntary movement or convulsionsAltered mental awarenessDue to excessive electrical activity in the brain

Etiology Mostly idiopathic (unknown) Genetic predisposition in 1% of casesAny major disease or illnessIn older adults age > 50, CVA is # 1 cause

Chaotic excessive electrical discharge of large aggregates of neurons in the brain

General CharacteristicsTonic: jaw fixed, hand clenchedClonic: rhythmic jerky contractions & relaxation, biting, froth on lipsNon-convulsive: changes in behaviors

OnsetMostly occur unpredictably at any timeSome are provoked

Classification of Seizure

Partial seizureSimple partialComplex partial (most common)Generalized seizureTonic-Clonic (i.e. Grand Mal)Absence (i.e. petit mal)**most common type

Sometimes, simple or complex partial can develop into generalized tonic-clonic

Simple Partial (focal seizure)Patients are conscious during seizureUnilateral hemispheric involvement, from a distinct, focal area of cerebral cortexSymptoms could be motor, somatosensory, or visual, depending on the brain area involved.

Complex PartialAltered or loss of consciousnessInvolve bilateral hemispheres, usually temporal lobes

Automatic, involuntary, repetitive behaviorsClumsy movementsConfused, mumbling, pulling clothing, head turns

Tonic-Clonic (grand mal)Sudden loss of consciousness & fallTonic: generalized rigidityClonic: very rapid generalized jerking movementsPostictal: altered speech, weakness, disorientation, muscle soreness, HA

Sudden cessation of ongoing consciousness activityStares into spaceOnly minor convulsive muscle activity or loss of postural controlSimple, brief, automatic movementsMore common in children, usually remit in adulthood

Absence Seizures (Petit Mal)

DiagnosisHistory from patient & observation from bystandersEEGIdentify underlying diseases, rule out other causes

TreatmentEducationAnticonvulsants (e.g. Gabapentin)SurgeryVagal nerve stimulation sends inhibitory signals to cerebrum

PrognosisIncreased mortality rates (due to underlying condition)Death from asphyxia (eating or swimming during a seizure)20 X risks of sudden death (cardiac arrhythmia, MI)Remission = 75% in idiopathic seizure diagnosed before age 10

Epilepsy

*dl = decilitre = 0.1 literLead poisoning occurs when lead builds up in the body, often over a period ofmonths or years. Even small amounts of lead can cause serious health problems.Children under the age of 6 are especially vulnerable to lead poisoning, which canseverely affect mental and physical development. At very high levels, leadpoisoning can be fatal.Lead-based paint and lead-contaminated dust in older buildings are the mostcommon sources of lead poisoning in children. Other sources of lead poisoninginclude contaminated air, water, soil, and some toys and cosmetics.

Lead may also affect brain function by interfering with neurotransmitter release and synapse formation. Lead may disrupt the functioning of mitochondria in the developing brain. Because the mitochondria are important for energy production within a neuron, a change in their function may damage the cell. *Incidence higher in low SES areas

Aka lead neuropathy*Lead, even at low concentrations, has the ability to increase the basal release of the neurotransmitters from the presynaptic nerve endings. This can occur both in the PNS and CNS. Micromolar concentrations of lead can cause the spontaneous release of dopamine, acetylcholine (ACh), and gama-aminobutyric acid (GABA). Control movement and emotional response are some of the brain processes that are affected by dopamine. An acetylcholine receptor has the responsibility for transducting nerve impulses to muscular contraction. GABA is an amino acid classified as a neurotransmitter. GABA is thought to play a role in the secretion of growth hormones according to some studies. Lead can also block the release of neurotransmitters when the action potential is taking place. This double effect of lead can have serious consequences on a developing nervous system. It can result in a decrease of pruning, what shapes the early brain, of an infant. The early brain, which has more synapses than an adult brain, is patterned according to the stimuli received during development. If there is an increase in neural activity, brought about by lead, the development process can be inhibited and have permanent effects on synaptic anatomy and function of the brain. It is believed that this is one of the causes of learning and behavioral problems that occur in children.

Precautions and Contraindications: lead paint, dust from lead paint (kids putting things in their mouths), inhaling car battery fumes, inexpensive plastic mini-blinds, water coming from lead pipes

Kids: more UMNL (plus more sensory issues)

Adults: more LMNL (peripheral myelin and axons)*Can be caused by head trauma or arteriosclerotic cerebrovascular disease

Seizures are often the first symptom of an intracranial mass

Hypoxia at birth can cause seizures during neonatal period**Triggering factors: stress, poor nutrition, missed med, skipping meals, flickering lights, illness, heat/humidityProdrome/early symptoms: headache, mood changes, lethargy, myoclonic jerking

Prodrome = early symptomSeizures are named by the lobe of onset

Partial Seizure secondarily generalized: develops from either a simple or complex partial seizure, generalized tonic-clonic seizure

*Like repeated blinking, twitch, etc.*Tonic phase generally very brief

May lose bowel or bladder control, bite tongue/lips/mouth or froth at mouth

Recovery period depends on length of seizure

Tonic Phase = eyes open, elbows flexed, arms pronated, legs extended, teeth clenched, pupils dilated, hold breath (cyanosis), lose bowel/bladderClonic Phase = violent tremor, eyes roll back, tachycardia, tongue may be bitten, breathing recommences at end of phase***change in level of consciousness but not a lossknow this is occurring if try to get the persons attention and they dont react (but can be easy to miss)

Examples: blinking, staring off into space, smack lips, chewing, hand movements

May miss a few words for a few seconds in a conversation if speaking

Person is unaware of the change in conscious control**GABA is the main inhibitory neurotransmitter in the CNSActivation of NMDA receptors increases neuronal excitability.

Medications: Phenobarbital, Dilantin, Valium, Tegretol, Depakene but will see side effects of these drugs (ataxia, dysarthria, dizziness, double vision)