Reading no further than the title of this chapter has already presented you with a conundrum: how exactly does one define “complex partial seizures of temporal lobe origin”? It's actually two difficult questions rolled into one seemingly innocuous phrase. First, a complex partial seizure (CPS) is defined as a seizure of focal onset accompanied by some impairment of awareness. Although this construction has a fair deal of practical value, particularly vis-à-vis driving safety, impairment of awareness can be very difficult to ascertain clinically.
Yet the second part is even more vexing. In theory, any seizure arising from a generator in the temporal lobe would qualify as a seizure of “temporal lobe origin.” But because our knowledge of epileptic circuits is paltry at best, this easy concept becomes exceedingly difficult to apply. What about a patient would unambiguously signify that his or her seizures were of temporal lobe origin? Frequent interictal spikes with a temporal maximum? Ictal recordings with origin in the temporal lobes? The history and semiology? The findings on imaging studies? In point of fact, it is well known that none of these are unambiguous indicators of seizure generation in the temporal lobes. The only way to truly confirm temporal lobe origin of seizures is to surgically resect the presumptive offending tissue and see whether seizures are abolished.
Of course, the “surgical standard” has a very high specificity but a very low sensitivity: it is applicable only to those with intractable epilepsy, and only to that subset who present for surgical evaluation and who are then found to have adequate concordant data, and low enough functional risk, to qualify for the resection. Thus, any conclusions about this population may or may not be applicable to the broader spectrum of patients with seizures of temporal lobe origin. With that caveat in mind, the following discussion will largely be drawn from the seizure-free surgical population, not only because of the lack of ambiguity, but because the large majority of the literature stems from this population. In the end, this may be the most relevant population to discuss in this volume, as the group of patients with temporal lobe seizures who are undergoing video-electroencephalographic (EEG) monitoring (VEM) will predominantly be those for whom surgery is being considered.
Little information is available regarding the incidence and prevalence of temporal lobe CPSs. This makes sense in light of the issue mentioned in the introduction: the tertiary care “surgical standard” for verification of temporal lobe origin is completely at odds with the broad-based community sample that is required for epidemiologic estimates. The best numbers come from Zarrelli et al.,1 who found that of 156 patients with epilepsy, 21 (13.5%) had symptomatic or cryptogenic temporal lobe epilepsy (TLE), corresponding to an incidence of 6.8 cases per 100,000 person-years. Unfortunately, this estimation is heavily compromised by the fact that the period of ...