Neuroimaging in the Evaluation of Headaches During Pregnancy
Abstract & Commentary
By Dara G. Jamieson, MD, Associate Professor, Clinical Neurology, Weill Medical College, Cornell University. Dr. Jamieson is a consultant for Boehringer Ingelheim and Merck, and is on the speaker's bureau for Boehringer Ingelheim, Merck, Ortho-McNeil, and Pfizer.
Synopsis: Emergent neuroimaging studies revealed underlying headache pathology, both in the brain and in sinuses, in 27% of pregnant women with headaches.
Sources: Ramchandren S, et al. Emergent headaches during pregnancy: Correlation between neurological examination and neuroimaging. Am J Neuroradiol 2007; 28:1085-1087.
Melhado EM, et al. Headache during gestation: evaluation of 1101 women. Can J Neurol Sci 2007;34(2):187-192.
Pregnant women frequently complain of headaches, with the prevalence of headaches during pregnancy reported to be as high as 35%. Women of childbearing age represent the group most afflicted with common primary headache disorders such as migraine and tension-type headaches. During pregnancy and the post-partum period, women may have new onset headaches that are usually primary, but some of these new headaches may be secondary to cerebrovascular disorders or mass lesions. In a prospective evaluation of more than a thousand pregnant women with a headache history, Melhado et al (2007) found that headaches during gestation were due to migraine in over 80% of women with a pre-gestational headache history. Generally, these headaches improved or resolved after the onset of the second trimester. However, in the rare women with a new onset headache during pregnancy, over half had a secondary headache. Less than half of pregnant women with a new onset headache, who had no prior headache history, ended up having a primary headache disorder.
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 an ominous cause. Ramchandren et al (2007) investigated the demographic factors, clinical presentations, and examination findings of pregnant women who presented with headache to the emergency department of an urban academic medical center. The authors hypothesized that abnormal findings on neurological examination would be predictive of an intracranial pathological condition on acute neuroimaging studies. The authors reviewed clinical and radiological variables on 63 pregnant women (median age, 26 years; range, 15-41 years) with headache. An odds ratio was generated to examine the likelihood of having an intracranial pathological condition in patients with neurological abnormalities on examination (abnormalities of mental state, cranial nerves, motor, sensory, gait, coordination and/or reflexes). Multivariate logistic regression analysis examined clinical, historical, and examination factors as predictors of a pathological condition on emergent neuroimaging studies.
The mean age of the 63 women was 25.9 years with a mean number of previous pregnancies of 2.2. The mean gestational age was 24 weeks (SD = 9). Multiparous African-American women constituted 63% of the subjects. Headaches were generally dull or throbbing, bilateral, and frontal. They were frequently accompanied by nausea, vomiting, photophobia, and phonophobia. A CT scan was obtained in 86% of women; an MR imaging study was obtained in 60%; almost half the pregnant women had both studies. Magnetic resonance venography and angiography were performed infrequently. While 49% of studies were normal and another 24% of studies found an incidental finding, unrelated to the headache, a pathological condition was found in 17 out of the 63 women. While 5 of these 17 women had sinusitis, 4 had cerebral venous thrombosis and 4 had reversible posterior leukoencephalopathy. Pseudotumor cerebri and intracranial hemorrhage were each found in 2 women.
Of the 26 patients who had focal findings on neurological examination, 10 had pathological neuroimaging findings. The abnormal findings on neurological examination of these women with pathological neuroimaging included mental status abnormalities, sensory abnormalities, seizures, cranial nerve deficits, and pathologic reflexes. Only one of the 4 women with reversible posterior leukoencephalopathy on neuroimaging had a non-focal neurological examination. Conversely, of the 17 patients with a pathological neuroimaging finding (including 5 with sinusitis), 7 had normal neurological examinations.
The odds of having an abnormal neuroimaging study were 2.7 times higher in those with abnormal results on neurological examination, compared to those with normal results, but because of a wide confidence interval, this finding was not statistically significant. While there were no demographic or clinical variables that were significantly predictive of intracranial pathological condition on emergent neuroimaging studies, abnormal mental status and increased hours of headache duration were suggestive of abnormal neuroimaging.
Most pregnant women with an acute headache and a prior headache history have a primary headache such as migraine or tension-type headache. A pregnant woman who presents for emergent evaluation with an acute headache should have a history and neurological examination focusing initially on the most common causes of primary headaches. However, when there is lack of a prior headache history and an abnormality on neurological examination, brain imaging should be performed to rule out a pathological cause of headache. In this paper, 12 out of 63 pregnant women with a headache had significant brain pathology, as opposed to sinus pathology, on neuroimaging. The authors of this study note that ordering neuroimaging studies on a pregnant woman often causes unnecessary concern about fetal effects, but that this fear is generally not warranted. They point out that the amount of fetal radiation exposure from a 10-section CT-scan is well below the amount associated with fetal abnormalities. While an abnormality on neurological examination increases the likelihood of finding a pathological cause for headache on imagining, the decision to order neuroimaging studies should not be based on the neurological examination alone. Even if the neurological examination is normal, the onset of a new headache in a pregnant woman is ominous and may require neuroimaging to rule out a pathologic etiology.