transcortical

Transcortical is an adjective that refers to a process or structure that passes through or crosses the cerebral cortex, the outer layer of the brain. The term is derived from the Latin prefix “trans” meaning “across” and the Greek word “cortex” meaning “bark” or “shell.” It is most commonly used in clinical neurology and neuroanatomy to describe specific types of seizures, aphasia, or surgical approaches that involve the cortex as a key pathway or site of intervention.

In epilepsy research, transcortical seizures are a form of focal motor epilepsy that originates within the cortex but spreads rapidly to involve other cortical areas. This rapid cortical spread can produce generalized motor activity that appears to be "genetic" but in fact originates focally. Transcortical seizures are distinguished from more focal or focal‑to‑bilateral seizures by their swift propagation through the cortex, often mediated by short‑loop excitatory networks or through white‑matter tracts. Seizure semiology may include tonic or clonic movements, often with delayed awareness loss.

Transcortical aphasia, another clinical entity associated with the word, describes loss of language function that results from damage to the posterior portions of the dominant hemisphere’s frontal, parietal, or temporal cortices while sparing the arcuate fasciculus. Patients may exhibit fluent speech but have impaired comprehension or word retrieval. In contrast to Broca’s or Wernicke’s aphasia, transcortical aphasia demonstrates both speech production and receptive language deficits that are due to cortical disconnection rather than a single eloquent area’s damage.

In neurosurgery, transcortical approaches are used to access deep brain structures or lesions located in the ventricles or within the basal ganglia. These surgical routes require incision through the cortical tissue, often involving the supplementary motor area or parietal lobe, to minimize damage to white‑matter pathways. Surgeons aim to limit postoperative deficits by carefully planning cortical entry points based on pre‑operative imaging and intraoperative mapping.