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.cite journal |author=Kushner D |title=Mild Traumatic Brain Injury: Toward Understanding Manifestations and Treatment |journal=Archives of Internal Medicine |volume=158 |issue=15 |pages=1617–1624 |year=1998 |pmid=9701095 |doi= |url=http://archinte.highwire.org/cgi/content/full/158/15/1617] cite journal |author=Kushner DS |title=Concussion in Sports: Minimizing the Risk for Complications |journal=American Family Physician |volume=64 |issue=6 |pages=1007–14 |year=2001 |pmid=11578022 |url=http://www.aafp.org/afp/20010915/1007.html |doi=] 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 point at which the body can no longer compensate.cite book |author= Valadka AB |chapter=Injury to the cranium | editor = Moore EJ, Feliciano DV, Mattox KL |title=Trauma |publisher=McGraw-Hill, Medical Pub. Division |location=New York |year=2004 |pages= 385–406 |isbn=0-07-137069-2 | accessdate= 2008-08-15 |url= http://books.google.com/books?id=VgizxQg-8QQC&pg=PA545&dq=tracheobronchial&client=firefox-a&sig=ATbisz-qr_r2zxfALuU6LnKYdYI#PPA544,M1] 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. 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.cite journal | last =Roski | first =RA | authorlink = | coauthors =Owen M, White RJ, Takaoka Y, Bellon EM | title =Middle meningeal artery trauma | journal = Surgical Neurology| volume =17 | issue =3 | pages = 200–203| publisher =Elsevier Science Inc | date =1981 | url = | doi = | pmid = ]

Because a patient may have a lucid interval, any 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. [cite journal | last =Kors | first =EE | authorlink = | coauthors =Terwindt GM, Vermeulen FL, Fitzsimons RB, Jardine PE, Heywood P, Love S, van den Maagdenberg AM, Haan J, Frants RR, Ferrari MD | title =Delayed cerebral edema and fatal coma after minor head trauma: role of the CACNA1A calcium channel subunit gene and relationship with familial hemiplegic migraine | journal =Annals of Neurology | volume =49 | issue =6 | pages =753–760 | publisher = | date =2001 | url = | doi = | pmid =11409427 ]

Lucid intervals may also occur in conditions other than traumatic brain injury, such as heat stroke [cite journal | last =Casa | first =DJ | authorlink = | coauthors =Armstrong LE, Ganio MS, Yeargin SW | title =Exertional heat stroke in competitive athletes | journal =Current Sports Medicine Reports | volume =4 | issue =6 | pages =309–317 | publisher = | date =2005 | url = | doi = | pmid =16282032 ] and the postictal phase after a seizure in epileptic patients. [cite journal | last =Nishida | first =T | authorlink = | coauthors =Kudo T, Nakamura F, Yoshimura M, Matsuda K, Yagi K | title =Postictal mania associated with frontal lobe epilepsy | journal = Epilepsy and Behavior| volume = 6| issue =1 | pages =102–110 | publisher = | date = 2005 | url = | doi = | pmid =15652742 ]

References

External links

* [http://rad.usuhs.edu/medpix/radpix.html?mode=single&comebackto=mode%3Dgeo_browse&recnum=1041 Medpix.com discussion of lucid interval] . Retrieved on February 6, 2007.