What would a standard EEG test find? Also: Temporal lobe epilepsy

Factual Questions
1

What does it look for? Would it be able to detect temporal lobe epilepsy? How would you determine if someone had that?

2

EKGs (electrocardiograms) look at hearts. EEGs (electroencephalograms) look for brain abnormalities.

I know a fair bit about the former, but much less about the latter.

3

:smack:

EEG.

Sorry, could a mod please change the title?

4

Done.

5

Considering their fairly “coarse” level, EEGs can still provide considerable information. Basically, there are four main uses (and, in the past, there were others but those have largely been supplanted by CTs and MRIs).

  1. EEG Used to Diagnose Epilepsy and Seizures
  • an EEG can reveal if someone is having a seizure at the time that it’s done (believe it or not, a person can be having a seizure and yet look like they’re sleeping peacefully or just babbling)
  • an EEG can reveal if there’s a so-called “seizure focus” in a person’s brain (i.e. an area of the brain which is likely to be a source of recurrent seizures)
  • an EEG can be particularly accurate at diagnosing specific forms of epilepsy such as what used to be called petit mal epilepsy but is now usually referred to as childhood absence seizures. The EEG is also helpful in diagnosing some rarer forms of childhood epilepsy
  • an EEG is invaluable in the diagnosis of “pseudoseizures” (which can be a very challenging diagnosis to make)
  1. EEG Used to Clarify Changed Level of Consciousness
  • as noted, a person can be “quietly seizing” - an EEG will uncover this
  • “Metabolic encephalopathies” (i.e. deranged brain function typically due to biochemical abnormalities of the blood) tend to have a distinctive pattern on EEG
  • the EEG is essential and invaluable to assist in the diagnosis of “brain death”
  1. EEG as a Tool to Diagnose Dementia
  • the EEG pattern in Creutzfeld-Jakob disease is essentially diagnostic (such a pattern in a person with a dementing process is virtually certain to be CJD).
  1. EEG as a Tool to Study Disordered Sleep (and Breathing)
  • the EEG can assist in things such as demonstrating that sleep apnea is associated with the onset of REM sleep

Now, in terms of what used to be called temporal lobe epilepsy but now renamed as complex partial seizures, I believe that the standard EEG may not be sensitive enough to pick up the brain wave abnormality. Hence, one or more supplemental EEG leads (i.e. wire) may be used - e.g. it can be placed through the nostril towards the back of the nose (this is called a ‘nasopharyngeal lead’). The reason that these extra leads are sometimes needed is that the temporal lobes of the brain are sort of folded under the rest of the brain and are thus fairly remote and “insulated” from the standard (and superficial) EEG leads. And that’s certainly the case for the ‘medial’ temporal lobe (that part of the temporal lobe closest to the midline). At this point, I better stop - I’m out of my league.

6

Well I knew a lass who developed epilepsy

When she died they found an enormous ‘benign tumour’ in her brain

An MRI scan would have picked that up.