Lucid interval

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This article is about the medical sign. For the Cephalic Carnage album, see 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. 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. Thereafter there is rapid decline as the blood collects within the skull, causing a rise in intracranial pressure, which damages brain tissue. An estimated 20 to 50% of patients with epidural hematoma experience such a lucid interval.[1][2] 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.[3]

Because a patient may have a lucid interval, any head trauma should be regarded as a medical emergency and warrants 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.[4]

Lucid intervals may also occur in conditions other than traumatic brain injury, such as heat stroke[5] and the postictal phase after a seizure in epileptic patients.[6]

[edit] References

  1. ^ Kushner D (1998). "Mild Traumatic Brain Injury: Toward Understanding Manifestations and Treatment". Archives of Internal Medicine 158 (15): 1617–1624. PMID 9701095. 
  2. ^ Kushner DS (2001). "Concussion in Sports: Minimizing the Risk for Complications". American Family Physician 64 (6): 1007–14. PMID 11578022. 
  3. ^ Roski, RA; Owen M, White RJ, Takaoka Y, Bellon EM (1981). "Middle meningeal artery trauma". Surgical Neurology 17 (3): 200–203. Elsevier Science Inc. 
  4. ^ 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. PMID 11409427. 
  5. ^ Casa, DJ; Armstrong LE, Ganio MS, Yeargin SW (2005). "Exertional heat stroke in competitive athletes". Current Sports Medicine Reports 4 (6): 309–317. PMID 16282032. 
  6. ^ Nishida, T; Kudo T, Nakamura F, Yoshimura M, Matsuda K, Yagi K (2005). "Postictal mania associated with frontal lobe epilepsy". Epilepsy and Behavior 6 (1): 102–110. PMID 15652742. 

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