| focal seizure | <neurology> A brief temporary alteration in movement, sensation or autonomic nerve function caused by abnormal electrical activity in a localised area of the brain. Focal seizures (i.e. Partial or Jacksonian seizures) usually cause no change in awareness or alertness. An example of a focal (partial) seizure would be rhythmic muscle contractions in one area of the body: lip smacking, mouth movements, drooling, head turning, eye movements or seemingly purposeful movements (for example picking at clothes). Other presentations may be strictly sensory with abnormal numbness, tingling or a crawling sensation to the skin. More unusual symptoms include changes in speech, thought, personality, mood, sensation of deja vu or hallucinations. (05 Jan 1998) |
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| focal spot | The site of bombardment by electrons and emission of X-rays from the anode of an X-ray tube. See: focal spot size. (05 Mar 2000) |
| focal spot size | The measured size of a focal spot, a function of its actual size and the angulation of the anode surface. See: focal spot. (05 Mar 2000) |