HDIB? Neuroscience Grand Rounds III: Seizure

Patient follow-up is always a double-edged sword. On one side, you need to see your patient to ensure that the ailment they originally sought to have remedied has been adequately taken care of before you give them the proverbial pat on the butt and tell them ‘go get ’em tiger, you’re all healed up!’.

Then there’s the other side – the follow-up visit due to complications. Sometimes things don’t go well as you had hoped, or as the healing process progresses, a new trigger or response rears its ugly head, prompting another visit to the good doctor for the patient.

We (sort of) have our first follow-up HDIB? Neuroscience Grand Rounds visit, with the news that fan favourite Arizona Diamondback Brandon McCarthy suffered a seizure, which appears to be related to his ongoing recovery from an epidural hematoma suffered as a result of a batted ball injury sustained back in September 2012.

There’s always a chance of happening any time you have a bruise on your brain it doesn’t actually ever heal, which always kind of leaves you at least somewhat vulnerable to it… So we knew the possibility was there. We had hoped we had kind of gotten past that.

While we discussed his initial injury here at HDIB?, given this most recent news, the post operative ramifications of the injury, as McCarthy alluded to in the quote above, need to be addressed. So, blogosphere neuroscientists in training, let’s do that here, yes? Get those textbooks dusted off and your stethoscopes cleaned up with some alcohol swabs – I have a feeling you’ve been putting it in places it shouldn’t be – and meet me in the lecture hall.


First, let’s start off with a definition of a seizure – it is the manifestation of a sudden disruption of neuronal activity in the brain as a result of an imbalance between the excitatory and inhibitory forces within a network of cortical neurons. In simpler terms, the signals being sent to and fro by the neural cells of the brain either get sped up, scrambled up, slowed down, or are sent too frequently than what is normal or expected. The primary culprits in this scenario is the neurotransmitter gamma-Aminobutyric acid, or GABA, and its corresponding brain receptors – GABA-A and GABA-B – which allow GABA to bind and therefore regulate excitability of the neurons. While there is a vast amount of additional information regarding the workings of GABA on the brain and its effects in seizure disorders, as well as the concomitant role of calcium concentrations and NMDA receptor activation in the brain, I will leave this minutiae for a continuing medical education course. In the end, this electrical ‘short’ is accompanied by behavioural and/or physical changes, with the changes manifested dependent upon what part of the brain is affected by this imbalance.

OK, so the wiring of the brain gets screwy and is marked by a multitude of symptoms – let’s talk more about the origins of those symptoms, as that will be how the different types of seizure are classified.

There are two overarching types of seizure, with each type having a number of subtypes: generalized- and focal-onset. General seizures affect the entire cortex and are further classified by the effect on the body; they also commonly involve a loss of consciousness. Given McCarthy’s description of his ordeal, he appears to have suffered some type of generalized seizure.

So what are the types, I hear you ask? There are six:

absence (aka petit mal): this is a brief (20 seconds or less) seizure exemplified by the sufferer being ‘absent’, defined by an impairment of consciousness and/or interruption of ongoing activities; commonly seen in an absence seizure are a blank stare, or a rolling of the eyes. This is normally suffered by children and rarely seen in adults.

myoclonic: these seizures are brief, arrhythmic, jerking, motor movements that last less than a second. Think about your Aunt Theresa dancing; this might be a myoclonic seizure. When these movements become more rhythmic and longer in duration, they become…

clonic: these are seizures that consist of rhythmic, motor, jerking movements that are a little more violent in nature compared to myoclonic forms. They occasionally do not involve loss of consciousness.

tonic: these are seizures that are sudden in onset, with the patient displaying tonic extension or flexion of the head, trunk, and/or arms and legs for several seconds. These commonly occur in relation to a person’s sleep pattern and level of drowsiness.

tonic-clonic (aka grand mal): the most commonly encountered form of seizure and one most implicated in epileptic disorder, these are the seizures you see portrayed in movies. They consist of generalized tonic extension of the extremities lasting for few seconds followed by clonic rhythmic movements and prolonged confusion once the episode subsides. This is more than likely the form of seizure McCarthy experienced, but we can only spitball and go by what was described by McCarthy. These types of seizure are commonly preceded by an aura – lightheadedness, dizziness, unusual emotions, intense feelings of doom or foreboding, and hallucinations are all possible hallmarks of an aura occurring. In reality, the aura is a simple partial seizure, which segues nicely into the other type of seizure – the focal-onset.

Briefly, the focal type of seizure affects only a certain portion of the cerebral cortex and can be broken down into simple- and complex-partial seizures. Simple partial seizures do not come with a loss of consciousness, while complex-partial seizures do; simple-partial seizures often lead to the occurrence of a complex-partial or a generalized seizure. Simple-partial seizures also do not spread from the focal area of the cortex from where they arise, whereas complex-partial forms often can. Again, I leave the nitty-gritty details of focal type seizures to another day, since it is less likely that this is the seizure type suffered by our patient.

So we have a seizure and we have done our due diligence and have ruled out other diagnoses, such as a sleeping disorder, a migraine headache, some sort of metabolic imbalance, such has hypoglycemia, and have confirmed the seizure with either a spinal tap, CT scan, MRI, or electroencephalogram (EEG). Good.

Now what?

You, watching ‘House, M.D.’ reruns on your iPad, how do we treat the seizure?

While there are a variety of treatment options, such as vagal nerve stimulation, a ketogenic diet, implantable neurostimulator, and occasionally surgery, pharmacotherapy in the form of an anticonvulsant is the treatment of choice in the majority of situations, you say?

Well said, that’s exactly the case – while you see these more elaborate treatment options pursued for those who are diagnosed with epilepsy, a situation like McCarthy’s typically only requires taking a pill or two of an anticonvulsant. While there are many types of anticonvulsant, some with one mechanism of action, some with multiple mechanisms and targets of action, they all are prescribed in an effort to prevent morbidity and further complications arising from a seizure. Sometimes, pharmacotherapy can be a temporary situation, sometimes, the patient must keep taking medication for the rest of their lives. While it is common to briefly treat a patient post-operatively with anticonvulsants prophylactically after a craniotomy to treat an epidural hematoma, if the patient does not suffer a seizure a week to ten days after surgery, the medication is frequently discontinued. With McCarthy suffering a seizure months after the initial injury, the chances of him suffering another is increased, which prompted his doctors to put him on medication.

What we’ve described fall in the category of epileptic seizures; there is also another form of seizure – the non-epileptic variety. Also known as pseudoseizures, psychogenic or cryptogenic seizures, on the surface they look like epileptic seizures, but differ in that they do not arise from aberrant electrical activity in the brain, and are considered psychological in origin versus physiologic. If you were to read an EEG of someone having a non-epileptic seizure, the results would be read as ‘normal’; also, these forms of seizure do not respond to anticonvulsant therapy, and are best treated with one of a number of psychiatric medications and psychological therapy. Just a little more food for thought as you go forth and become guardians of the nervous system.

Like with our previous McCarthy-ian Grand Rounds, we see the wonders and advances in neuroscience and medicine at their best, as not only will McCarthy have a normal life in spite of the seizure, he will be able to continue his baseball career.

Now, about that shoulder problem

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