Lucid interval

In emergency medicine, a lucid interval is a temporary improvement in a patient's condition after a traumatic brain injury, after which the condition deteriorates. A lucid interval is especially indicative of an epidural hematoma. An estimated 20 to 50% of patients with epidural hematoma experience such a lucid interval.[1][2]

Indications

When related to hemorrhage, the lucid interval occurs after the patient is knocked out by the initial concussive force of the trauma, then lapses into unconsciousness again after recovery when bleeding causes the hematoma to expand past the extent for which the body can compensate.[3] After the injury, the patient is momentarily dazed or knocked out, and then becomes relatively lucid for a period of time which can last minutes or hours.[3] Thereafter there is rapid decline as the blood collects within the skull, causing a rise in intracranial pressure, which damages brain tissue. In addition, some patients may develop "pseudoaneurysms" after trauma which can eventually burst and bleed, a factor which might account for the delay in loss of consciousness.[4]

Because a patient may have a lucid interval, any significant head trauma is regarded as a medical emergency and receives emergency medical treatment even if the patient is conscious.

Delayed cerebral edema, a very serious and potentially fatal condition in which the brain swells dramatically, may follow a lucid interval that occurs after a minor head trauma.[5]

Lucid intervals may also occur in conditions other than traumatic brain injury, such as heat stroke[6] and the postictal phase after a seizure in epileptic patients.[7]

See also
  • Natasha Richardson
  • Mark Donohue

References
  1. Kushner D (1998). "Mild Traumatic Brain Injury: Toward Understanding Manifestations and Treatment". Archives of Internal Medicine. 158 (15): 1617–1624. doi:10.1001/archinte.158.15.1617. PMID 9701095. Archived from the original on 2008-05-14.
  2. Kushner DS (2001). "Concussion in Sports: Minimizing the Risk for Complications". American Family Physician. 64 (6): 1007–14. PMID 11578022.
  3. Valadka AB (2004). "Injury to the cranium". In Moore EJ, Feliciano DV, Mattox KL (eds.). Trauma. New York: McGraw-Hill, Medical Pub. Division. pp. 385–406. ISBN 0-07-137069-2. Retrieved 2008-08-15.
  4. Roski, RA; Owen M; White RJ; Takaoka Y; Bellon EM (1981). "Middle meningeal artery trauma". Surgical Neurology. Elsevier Science Inc. 17 (3): 200–203. doi:10.1016/0090-3019(82)90280-4. PMID 7079938.
  5. Kors, EE; Terwindt GM; Vermeulen FL; Fitzsimons RB; Jardine PE; Heywood P; Love S; van den Maagdenberg AM; Haan J; Frants RR; Ferrari MD (2001). "Delayed cerebral edema and fatal coma after minor head trauma: role of the CACNA1A calcium channel subunit gene and relationship with familial hemiplegic migraine". Annals of Neurology. 49 (6): 753–760. doi:10.1002/ana.1031. PMID 11409427.
  6. Casa, DJ; Armstrong LE; Ganio MS; Yeargin SW (2005). "Exertional heat stroke in competitive athletes". Current Sports Medicine Reports. 4 (6): 309–317. doi:10.1097/01.csmr.0000306292.64954.da. PMID 16282032.
  7. Nishida, T; Kudo T; Nakamura F; Yoshimura M; Matsuda K; Yagi K (2005). "Postictal mania associated with frontal lobe epilepsy". Epilepsy & Behavior. 6 (1): 102–110. doi:10.1016/j.yebeh.2004.11.009. PMID 15652742.
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