Temporal Lobe Epilepsy
One of the more controversial topics in neurology and psychiatry is the connection between Temporal Lobe Epilepsy (TLE) and atypical disorders of mood and behavior. Classic training in neurology or psychiatry may give providers a strong opinion about this topic, but a true look at the literature and sufficient experience with patients tends to produce more humility.
Representation of some of the major pathways connecting the temporal lobe to the major mood and behavior networks
Sourced from Google: DOI: https://doi.org/10.1523/JNEUROSCI.0374-20.2020
The complex research into TLE and behavioral disorders began in the early 80s. It was already well known that most focal seizures (epilepsy starting in one area of the brain) either begin in the temporal lobe or send their first abnormal signals to the temporal lobe where they expand. However, in the early 80s, a few psychiatrists and neurologists began theorizing that many patients with mood and behavior disorders and atypical psychotic symptoms, actually had an epileptic cause. They began diagnosing everyone with depression, psychosis, or behavioral disorders that didn’t respond to classic medications for those symptoms with TLE due to evidence that some patients who didn’t respond to antidepressants responded to antiepileptic drugs.
This led to a backlash in the literature, with the majority of neurologists saying that a diagnosis of epilepsy required clear evidence with brain wave testing to prove, and even if there was evidence of epilepsy, that didn’t prove that epilepsy was the cause of the behavioral disturbance. Now, the majority of trainees never hear about this historical debate or they get a very cursory teaching from one perspective or another. Very few trainees are taught about the history of this debate and the many arguments on both sides.
For patients, there is a lot of frustration. They feel (or are overtly told) that an EEG should give a clear answer, but it isn’t that simple. The type of focal seizure that would cause these behavioral disturbances would be very deep in the brain, and over a very small area of the brain. Surface EEGs (the kind most people receive) only find seizure activity near the surface and require at least 4 cm of brain area to have epileptic changes for it to clearly show up. Often, there will be some evidence of “cortical irritability” or slowing (called temporal Intermittent rhythmic delta activity) but these can also be seen in people with no evidence of epilepsy. Other arguments are based on response to treatment. If a symptom resolves with an epilepsy drug, they believe that means it was caused by epileptic activity. However, many epilepsy drugs have significant effects on psychiatric symptoms, some of them being prescribed as mood stabilizers more often than as antiepileptics.
Therefore, some physicians see the same evidence and use it to support their own idea, either for or against the diagnosis. Their bias can lead to a placebo (or nocebo) effect in their patients, further reinforcing their bias. Since the only way to prove or disprove their theory for an individual patient would be very invasive testing (electrodes placed in the brain while symptoms are monitored) a final answer is rarely reached.
There are more issues that have been part of the discussion historically that are rarely part of classic training for psychiatrists or neurologists, or even epilepsy specialists. Many patients and physicians are aware of classical behaviorism. If you pair a good behavior with a reward, or a bad behavior with a punishment (or removal of a reward), you can dramatically change behavior and mood. Now imagine that while a child is learning about good and bad behaviors, there is a random surge of electrical activity in either the reward or punishment brain circuits that has no relationship to the training. It wouldn’t be very different from a painful shock being randomly given to a child, and any psychology 101 student has seen the learned helplessness research on that in animal models.
Lastly, even if an epilepsy doctor decides that a disorder of mood, thought, or behavior is caused by TLE, that doesn’t resolve the problem. They may know that some epilepsy medications are given as mood stabilizers, but they may not know about the subtle differences that may make one choice better than another. They may avoid certain very useful medicines because of training that they increase the risk of seizure, even though they likely have no real risk at the appropriate doses. Lastly, epilepsy doctors aren’t trained to manage complex behavioral complaints, and may not understand how to integrate medication management with psychotherapy. Worse, if a psychiatrist is convinced it is TLE and a neurologist is convinced it is not, both may refuse to treat.
The temporal lobe is a fascinating topic in behavioral neurology because the main circuitry for mood, reward, and memory are functionally connected with and even driven by this limbic system structure. Other areas of the temporal lobe can lead to strange disturbances of perception and thought with classic syndromes like out of body experiences or autoscopy, hyperreligiosity, creativity, and manic symptoms. Some of humanity’s deepest psychic experiences can be elicited by giving small electrical stimuli to the temporal lobe and surrounding areas. Discovering whether a symptom is due to epileptic activity or just a hyperactive area can often not be definitively proven. Moreover, if there is frequent epileptic activity, that can create hyperactivity afterwards, so both can be the case. Because of this, epileptic drugs may stop the seizure activity, but it may take a long time for the hyperactive connections to slow down. Even in classic cases of mania, panic, or psychosis caused by proven seizure activity, it can take months for patients to return to normal after the epilepsy has been treated.
If you or a loved one is struggling through this complex diagnosis, I hope that this article has validated any frustration or confusion you may have experienced. There is hope, but the answers often only come with time and an honest humility that we only have so many tools and treatments available and nothing in medicine is 100%. If you would like to request a consult for you or a family member with questions about TLE, please contact us today.
