- Last Updated on 14 December 2016
In some cases, a relatively small abnormality (a.k.a. "focal lesion") is found to cause infantile spasms and other forms of epilepsy. Common examples of such lesions include focal cortical dysplasia (FCD, an often subtle or asymptomatic developmental malformation in the brain), cortical tubers (characteristic of a disorder called Tuberous Sclerosis Complex), a variety of low-grade (slow-growing) tumors, and areas of damaged brain which may occur in the setting of stroke or intracranial bleeding.
Focal lesions are commonly confirmed and characterized by a variety of neurodiagnostic tests including electroencephalography (EEG), magnetic resonance imaging (MRI), positron emission tomography (PET) or single photon emission computed tomography (SPECT), and magnetoencephalography (MEG). In some cases, additional studies are needed as well, including invasive electrical monitoring with depth electrodes or electrocorticography (ECoG), functional magnetic resonance imaging (fMRI), or the intracarotid amobarbital procedure (also called the Wada test, a procedure in which a portion of the brain is temporarily "inactivated" by medication to simulate a post-surgical state). These studies aim to determine the structural and functional characteristics of the lesions, both during seizures (ictal), and in between seizures (interictal).
If a lesion is identified and deemed amenable to surgical removal, excellent rates of seizure-freedom are possible when a lesion is completely removed. This of course poses several challenges—the key being the functional consequences of surgical removal of a part of the brain. The decision making process must consider the likelihood of seizure-freedom after surgery, the risks of surgery itself, and the potential loss of function associated with removing a specific part of the brain. In consultation with patients (and parents) these decisions are made by multidisciplinary teams including neurologists (epileptologists), neurosurgeons, neuroradiologists, neuropsychologists, and a variety of other specialists who may be needed in special cases.
Surgery to remove brain regions generating seizures is not a therapy of last resort. In general, if a patient has failed therapy with several well-chosen medications, surgery may be considered.