Intravenous magnesium

By | May 13, 2012

Intravenous magnesium:

A. Is poorly tolerated in the treatment of acute migraine.

B. Has been shown to inhibit central sensitization with acute migraine.

C. Shows preferential benefit with migraine with aura as compared to migraine without aura.

D. Is effective in migraine based on an antiserotonergic mechanism.

E. All of the above

The answer is C. Intravenous magnesium sulphate, an N-methyl-D-aspartate (NMDA) receptor inhibitor, has been used in the acute treatment of migraines with variable efficacy. It is well tolerated when given in the ED. Central sensitization has not yet been shown to be its mechanism of action. Magnesium sulphate may preferentially benefit patients with migraine with aura. A randomized, double-blind, placebo-controlled study assessed the effect of 1 g magnesium sulphate on the pain and associated symptoms in patients with migraine with and without aura. Patients with migraine without aura showed no statistically significant difference with magnesium sulphate as compared to placebo in relief of pain or nausea. Some benefit on photophobia and phonophobia was noted in patients who received magnesium sulphate. Migraine with aura patients treated with magnesium sulphate showed a statistically significant improvement of pain and of all associated symptoms as compared with controls. (Bigal, Bordini, Tepper, & Speciali, Cephalalgia 2002)

What is the approximate lifetime prevalence of cluster headache?

A. One in 100 people

B. One in 1, 000 people

C. One in 10, 000 people

D. One in 100, 000 people

E. One in a million people

The answer is B. Cluster headache is a male-predominant trigemino-autonomic cephalgia (TAC) with a low prevalence. A meta-analysis of population studies of cluster headache showed a lifetime prevalence of 124 per 100, 000 [confidence interval (CI) 101, 151] and a 1-year prevalence of 53 per 100, 000 (CI 26, 95). The overall male-to-female ratio was 4.3 but it was higher in chronic cluster headache (15.0) compared with episodic cluster headache (3.8). The ratio of episodic to chronic cluster headache was 6.0. The analysis revealed a relatively stable lifetime prevalence suggesting that about one in 1000 people suffers from cluster headache. While cluster headaches are male predominant, they may be under-diagnosed in women. (Fischera, Marziniak, Gralow, et al., Cephalalgia 2008)

In a pregnant woman with the new onset of severe headache, which of the following is true?

A. Since headaches are very rare during pregnancy, a severe headache indicates serious pathology.

B. Imaging of the brain should not be performed unless there is a motor or cranial nerve deficit on neurological examination.

C. Imaging of the brain should be considered even if the neurological examination is normal.

D. Migraine is the most common cause of new-onset headache in a woman without any pregestational history of headaches.

E. Computed tomography (CT) scanning of the brain of pregnant women should never be performed because of radiation risk to the fetus.

The answer is C. Most pregnant women with an acute headache and a prior headache history have a primary headache such as migraine or TTH. Because the care of a pregnant woman must address the health of both the mother and the fetus, evaluation of the pregnant woman with a headache should focus on the most likely headache diagnosis, while ruling out a secondary cause of headache. An abnormal neurologic examination, including an abnormal mental status, and increased headache duration may predict abnormal neuroimaging. The amount of fetal radiation exposure from a 10-section CT scan is well below the amount associated with fetal abnormalities, and fear of fetal radiation exposure should not preclude emergent CT imaging when it is felt to be appropriate. (Ramchan-dren, Cross, & Liebskind, Am J Neuromdiol 2007)

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