Neurology: Day 12, 13, 14, 15

Try as you may, you cannot get through a Neurology rotation without learning about seizures. They are everywhere. The inpatient list is filled with different forms of seizures, there are countless anti-epileptic drugs with varying adverse effects, and it is of vital importance that every doctor, no matter in which field they practice, understand the basic management of seizures.

So, what is a seizure? It's when there is a sudden abnormal discharge of electrical activity in the brain, which causes symptoms which are consistent with where the electrical discharge occurs in the brain (variable presentation). It occurs in 1-2% of the population. Despite the long-held belief that seizures most often begin in childhood, the most common age of onset is actually in the elderly (the second most common is in infants).

So, what causes a seizure? There are a few possibilities, easy to remember as the FOUR M'S & FOUR I'S:

1. Metabolic: hypo/hyper-natremia, hypo/hyper-glycemia, hypocalcemia, uremia, thyroid storm, hyperthermia
2. Mass lesion: brain metastases, primary tumor, hemorrhage.
3. Missing drugs: noncompliance with anticonvulsants or acute withdrawal from depressants (alcohol, benzos, or barbiturates)
4. Miscellaneous: 
1. Non-epileptic seizures (often related to neurotransmitters and respond to psychiatric medications more effectively than anticonvulsants)
2. Eclampsia (Treatment: Magnesium)
3. Hypertensive Encephalopathy (causing cerebral edema)
5. Intoxication: cocaine, lithium, heavy metals, carbon monoxide poisoning
6. Infections: sepsis, bacterial or viral meningitis, brain abscess
7. Ischemia: stroke, TIA
8. Increased Intracranial Pressure: especially following a trauma

What do seizures look like? Most commonly (70%), a seizure can be classified as a Partial Seizure, which produces localized features which reflect the area in the brain that is abnormally firing. Seizures can be divided into four categories:

1. Simple Partial Seizures: focal seizure without loss of awareness
1. May involve unilateral tonic-clonic movements
2. Complex Partial Seizures: focal seizure with loss of consciousness/awareness
1. Automatisms last from 1 to 3 minutes: purposeful, involuntary, and repetitive movements
1. Example: Lip-smacking (temporal lobe)
3. Primary Generalized Seizures:  may be tonic-clonic or myoclonic + postictal confusion
1. Absence: onset must be in childhood only. No loss of postural tone or continence, no postictal confusion.
1. Drug of choice: Ethosuximide
2. Juvenile Myoclonic Epilepsy: Often in young females. 
1. Drug of choice: Valproate (1st line - but is teratogenic); or Lamotrigene
4. Secondary Generalized Seizures: Begins focal, spreads to general.

So, what do you do to work up a patient with a possible new-onset seizure? Look at what are the causes of seizures (above) and investigate accordingly. If it is a seizure in a patient with a positive history for seizures, the first step is likely to check the drug's level in the patient's serum to ensure that it is at an adequate dosage level.

1. CBC, Electrolytes + calcium, Blood Glucose, Liver and Renal function tests, Urinalysis.
2. EEG: aids in diagnosis (not useful without clinical correlation however!)
3. CT Brain: to quickly rule/out structural abnormalities
4. MRI Brain, with and without contrast: sensitive for picking up structural abnormalities
5. LP, Blood Cultures if the patient is febrile.

So, what is the treatment plan for someone with seizure?

1. As always: A,B,Cs (airway, breathing, circulation) come first!
2. History of seizures are often caused by noncompliance with medication or improper medication level:
1. Administer a loading dose of anticonvulsant medication and continue as previously prescribed. 
2. If seizure persists: increase the dosage of the anticonvulsant until signs of toxicity appear.
1. Add a second anticonvulsant drug if seizures not controlled with first drug.
3. If seizure is controlled: continue medication for 2 years.
1. If remain seizure-free for 2 years (+ seizure free routine EEG), taper from medications cautiously.
3. New-Onset Seizure:
1. Generalized or Partial: Phenytoin or Carbamazepine are drugs of choice
1. Others to consider include phenobarbital, valproate, and primidone
2. Absence Seizures: Ethosuximide, Valproic Acid

So, what if the patient remains in a seizure? That's known as "Status Epilepticus", and is a medical emergency. The mortality rate approaches 20%! The current accepted minimal time frame is >5 minutes of seizure activity with LOC.

• May be caused by poor compliance with medications, alcohol withdrawal, intracranial infection, neoplasm, metabolic disorder, or drug overdose.
• Management: Establish an airway. Administer IV diazepam, IV phenytoin, and 50mg dextrose (plus thiamine). If seizure persists, administer IV phenobarbital.

For a bit of hopeful news, some dogs may be trained to sense an impending seizure in their owner. This can be particularly helpful in children, who may be unable to sense that a seizure is coming on as well as to notify the child's guardian of a seizure. They sure are smart creatures, aren't they? ;)