Epilepsy and Other Causes of Seizure

Focal/Partial Seizures

Focal, partial, or secondary seizures, have a focal onset from a cortical problem. There are four main types, which can occur together or at different points of time. Depending on where the specific area of focus is, very discrete symptoms can occur.

simple partial motor seizure

• no loss of consciousness
• focal clonic jerks that can spread (Jacksonian march)
• focal tonic (ie head turing, eye deviation)

simple partial sensory seizure

• numbness or tingling (somatic cortex)
• visual elementary shapes, colours (occipital)
• auditory: elementary sounds (superior temporal lobe)
• usually very stereotyped; more complex hallucinations suggests psychosis
• olfactory, gustatory (medial temporal lobe)
• multimodal experiential or 'psychic' (temporal lobe)

complex partial

• usually affects temporal or frontal lobe
• one of the most common
• onset at any age
• huge range of clinical expression
• stop and stare: impaired awareness
• memory loss
• automatisms (lip smacking, chewing, verbal, complicated gestures
• subcortical functions (walking, driving!) can continue during this loss of consciousness
• typically last 1-2 minutes, but can last hours
• often weird sensation beginning above epigastrium and traveling behind sternum

secondary generalized tonic-clonic

• spead from localized area through limbic system to rest of cortex
• often begins with "cry"
• may have cyanosis
• may or may not have aura
• loss of consciousness
• tonic - rigid; clonic - shaking
• bilateral motor involvement with consciousness cannot be seizure, as if both hemispheres are seizing, LOC will occur
• urinary incontience, tongue biting

Generalized

Generalized seizures have global onset in both hemispheres. The mechanism likely depends on a diffusely hyperexcitable cortex and complex interactions between thalamus and cortex, possibly involving calcium channels. Generalized seizures are more likely to be genetics based.

Febrile seizure

Febrile seizures normally begin between 6 months-6 years, and are associated with a rapid rise in temperature. In order to make the diagnosis, it is important to determine:

• no neurological abnormalities before or after (suggesting CNS infection)
• no history of non-febrile seizures
• typical: generalized tonic-clonic, less than 15 minutes duration, no recurrence in 24 hours
• atypical: focal origin, more than 15 minutes duration, more than one in 24 hours

Absence

• relatively unusual
• childhood onset
• brief periods (10-15s) with no warning
• arrest of behaviour; simple automatisms (blinking) sometimes
• no postictal phase
• may have dozens per day
• EEG shows characteristic "3 per second spike and wave"
• can use calcium channel active anticonvulsants

Absence seizures can be distinguished from partial seizures based on age of onset (young), duration (brief), an often high frequency, lack of postictal phase, automatisms, and EEG findings.

Generalized tonic-clonic

• full-body flexion-contraction
• onset in childhood or adolescence
• interictal EEG can show generalized spike waves
• can occur on its own or with other general seizure types

Myoclonic Seizures

• brief lightening-like jerks
• isolated or repetitive showers
• can have "epileptic" and "nonepileptic" myoclonus; can occur with diverse clinical conditions
• very complicated physiology
• juvenile myoclonic seizures respond extremely well to valproic acid

Atonic Seizures

• also called drop seizures, result from brief loss of muscle tone
• short lasting - less than 15 seconds - with full recovery
• begin in childhood and may persist

History

Seizure itself

• duration
• body parts affected, in which order
• premonitory signs
• neurological symptoms

Children

• pregnancy and birth history
• developmental milestones

Evaluating possibility of past seizures:

• ever chewed your tongue severely at night?
• ever lost control of your bladder or bowels?
• every woken up with a dislocated shoulder or compression fracture?

Cardiac causes:

• family history
• developmental delay in children

Precipitants include:

• sleep deprivation
• alcohol
• drugs
• TV screen
• strobe light
• emotional upset
• head trauma
• toxic exposure

Prodromal symptoms can include:

• aura
• smells

Post-ictal symptoms can include:

• decreased level of consciousness
• headache
• sensory abnormalities
• tongue pain
• limb pain
• Todd's paresis: if during the postictal phase they can't speak, it suggests the language centre is the area of focus

Medications

• what medications are being used?
• duration
• compliance

neurologic history is very important from both patient and witness

Physical Exam

ABC's ?Cushing's triad

Temperature

Neuro exam

• MMSE
• cranial nerves
• bulk, tone, strength
• sensation
• reflexes
• cerebellar

Tongue: evidence of biting

Cardiovascular

• carotid and cranial bruits

Skin

• neurocutaneous syndromes: tuberous sclerosis, NF1

Lab Investigations

For an acute, unexplained seizure, perform an immediate glucose check. Other bloodwork may include:

• CBC (especially in pediatrics: hemolytic uremic syndrome)
• electrolytes

Ensure neurological exam is normal before performing lumbar puncture for meningitis.

In follow-up, serum dilantin levels should be measured, along with CBC.

Diagnostic Imaging

For simple febrile seizures, no diagnostic studies are routinely indicated.

EEG can be used to localize seizure foci. Interictal (non-clinical) waves can sometimes be seen

Neuroimaging is helpful for determining aetiology. MRI is vastly superior than CT (King et al, 1998).

ECG to evaluate cardiac reasons.