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I was wondering, is there a possibility of an something similar to an epileptic focus to exist within the spinal cord?

Note I am using the terminology "epileptic" loosely here, principally for the lack of a better name for it. When I say epileptic focus I mean an excitable area capable of sustaining a pathological rhythmic electrical activity which may or may not extend to other areas of the central nervous system.

I believe it is due to the connection types that occur within the spinal chord (closed loops that exist there are resistant to this) and as such this might be true for other CNS areas (epileptogenic susceptible tissue might be specific of cortex areas). But I did some research on the topic and couldn't find any data on this.

If it isn't possible to have this problem on the spinal chord then, why is that?

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  • $\begingroup$ What I did find is that some types of damage (ncbi.nlm.nih.gov/pubmed/1775364) may trigger something like an epileptic focus - couldn't find if it is becomes a permanent inductor of seizures, probably not. $\endgroup$ – user27221 Dec 3 '15 at 4:31
  • $\begingroup$ Another possibility is that electrical activity within the spinal chord is hard to measure (jn.physiology.org/content/73/1/399.short mentions briefly this difficulty) $\endgroup$ – user27221 Dec 3 '15 at 4:33
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Short answer
Epilepsy is a disorder confined to the brain.

Background
Terminology is crucial in this question. The International League Against Epilepsy (ILAE) defines epilepsy as a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures and by the neurobiologic, cognitive, psychological, and social consequences of this condition. ILAE defines an epileptic seizure as a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain (Fisher et al., 2005).

Hence, by definition, epilepsy is a disorder of the brain. Note that the ILAE is an authorative organ and their definition overrides whatever your medical textbook on internal medicine says.

An epileptic focus is a commonly used term, but as far as I know not well-defined. It's often used in relation to EEG and other methods such as MRI and PET that attempt to define the hot spot of seizure activity. More strictly defined terms in this regard are eloquent cortex and epileptogenic zone. The eloquent cortex refers to any cortical area in which injury produces symptomatic cognitive or motor deficit. The epileptogenic zone refers to the region of cerebral cortex that is both necessary and sufficient to generate epileptic seizures. Its entire removal can be used as a treatment for intractable epilepsy (Richardson, 2003).

With regard to your question, I expect you are referring to the epileptogenic zone. By definition, this refers to a region in the brain.

References
- Fisher et al, Epilepsia (2005); 46(4): 470-2
- Richardson, Brit Med Bull (2003); 65: 179–92

Note
I expect this answer may not be entirely satisfactory. If you are looking to the physiological basis of the occurrence of seizures and why they occur in the brain and not in the spinal cord, it may be wise to formulate a more specific separate question. Preferably do not grossly edit this question given it received three answers. vervet's answer on focal epilepsy clearly shows the confusing terminology in epilepsy world. Focal epilepsy is not the same as an epileptic focus. However, epileptic focus is a term often used for focal epilepsy. Long story short, specific answers need specific questions, preferably with the definitions embedded to prevent deleted answers and under-appreciated answers like vervet's.

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  • $\begingroup$ Thanks for the well-round well composed answer, but you are right, I this is not the answer for which I was looking. $\endgroup$ – user27221 Dec 3 '15 at 4:05
  • $\begingroup$ I've made (hopefully) suitable edits to made clearer what I meant. $\endgroup$ – user27221 Dec 3 '15 at 4:28
  • $\begingroup$ Why the downvote? $\endgroup$ – AliceD Dec 3 '15 at 8:26
  • $\begingroup$ Because you knew you were not answering my question but answered it anyway. $\endgroup$ – user27221 Dec 5 '15 at 17:08
  • $\begingroup$ Also, because you defined epilepsy as a brain disease (ok, according to some reliable sources) but my question is intrinsically related to why is this a brain disease and not a CNS disease. Some older sources would treat is as more generally as a CNS disease, such as ncbi.nlm.nih.gov/pmc/articles/PMC1675106 and this is what I want to clarify. $\endgroup$ – user27221 Dec 5 '15 at 17:09
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Epilepsy is a brain disorder caused by abnormal electrical activity in the brain, which is what often produces seizures. Focal epilepsy just involves part of the brain, while generalized epilepsy cannot be localized to a specific part.

A focal epilepsy could therefore not be caused by a spinal cord lesion.

Some conditions also affecting the spinal cord may predispose patients to epilepsy. For example, multiple sclerosis patients are known to have higher rates of epilepsy. However, the epileptic focus is still in the brain.

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    $\begingroup$ You didn't answer what I asked and you didn't put in any pertinent references. Also I was not asking about spinal lesions, nor multiple sclerosis. Epilepsy is usually described as CNS disease and the spinal cord is a part of the CNS $\endgroup$ – user27221 Nov 15 '15 at 3:07
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    $\begingroup$ Also I was not talking about lesions or diseases of the spinal cord, since I know that if you put something there you can cause a seizure ncbi.nlm.nih.gov/pubmed/21992196, what I meant was a spontaneous focus or a spontaneous activity without generalization. $\endgroup$ – user27221 Nov 15 '15 at 3:14
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    $\begingroup$ @user27221 What I am saying is epileptic seizures always originate in the brain. Spinal cord seizures are much less common. If your question is about seizures in general you should remove the word epileptic. $\endgroup$ – Harry Vervet Nov 15 '15 at 3:34
  • $\begingroup$ As defined by Harrison's Textbook of medicine: "Epilepsy describes a condition in which a person has recurrent seizures due to a chronic, underlying process.", whereas "A seizure (from the Latin sacire, “to take possession of”) is a paroxysmal event due to abnormal, excessive, hypersynchronous discharges from an aggregate of central nervous system (CNS) neurons." The names are not related to any spacial aspect whatsoever. $\endgroup$ – user27221 Nov 15 '15 at 3:52
  • $\begingroup$ +1 for the distinction between focal and generalized epilepsy. $\endgroup$ – AliceD Nov 16 '15 at 1:57

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