Hyponatremia and cerebrovascular spasm in aneurysmal subarachnoid hemorrhage.
BACKGROUND
Hyponatremia develops in approximately a third of patients with aneurysmal subarachnoid hemorrhage (SAH). Studies have been conflicting about the association between hyponatremia and cerebrovascular spasm (CVS).


OBJECTIVE
To investigate whether hyponatremia can signal the onset of CVS.


METHODS
Retrospective chart review of all patients with SAH treated at a tertiary-care university hospital from January to May 2002.


METHODS
106 patients were included in the study. Serum sodium levels were recorded from days 1 to 14 of hospitalization. Hyponatremia was defined as serum sodium level<135 meq/l and a fall in sodium level of >4 meq/l from the admission sodium level. The presence of CVS was determined by transcranial doppler sonography. Patients were assigned to one of four groups based on the presence or absence of CVS and hyponatremia.


METHODS
Student's t-test was used for comparison of means. A logistical regression model was constructed and odds ratios (OR) were calculated.


RESULTS
41 patients developed hyponatremia and 44 developed CVS. Among the 41 with hyponatremia, 22 (54%) had evidence of CVS, whereas among the 65 patients without hyponatremia, 22 (34%) had evidence of CVS (P=0.023). Among those with hyponatremia, the mean sodium drop was 7.9 meq/L in those with CVS compared to 7.0 meq/L in those without CVS (P=0.068). More than half of those with hyponatremia and CVS (13/22) developed hyponatremia at least a day before CVS was diagnosed.


CONCLUSIONS
In patients with SAH, hyponatremia is associated with a significantly greater risk of developing CVS and may precede CVS by at least one day.
Chandy
Dipak
D
Department of Medicine, New York Medical College, Valhalla, NY 10595, USA. nandipak@hotmail.com
Sy
Roger
R
Aronow
Wilbert S
WS
Lee
Wei-Nchih
WN
Maguire
George
G
Murali
Raj
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012189:Retrospective Studies; D012964:Sodium / Q000097:blood; D013345:Subarachnoid Hemorrhage / Q000097:blood / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods; D020301:Vasospasm, Intracranial / Q000097:blood / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*
D012964:Sodium