A 17-year-old primigravida at 29 weeks gestation comes to the clinic due to headaches. For the last 2 weeks, she has had an intermittent throbbing pain in the left frontal region when she wakes up. The pain is sometimes accompanied by a rhythmic pulsating sound. Acetaminophen provides minimal improvement. The patient has had no fever, right upper quadrant pain, contractions, or vaginal bleeding. She recalls no trauma and has no chronic medical conditions. Prepregnancy BMI is 31 kg/m², and the patient has gained 20 kg (44 lb) so far. Temperature is 37.1 C (98.8 F), blood pressure is 136/76 mm Hg, pulse is 80/min, and respirations are 18/min. Fetal heart rate is 160/min. There is no neck stiffness. Visual field testing is normal. Funduscopic examination shows bilateral optic disc edema. Bilateral deep tendon reflexes are 2+. The remainder of the neurologic examination is unremarkable. Urinalysis has trace protein. Which of the following is the best next step in evaluation of this patient?

Question

Quizplus · Accepted Answer

11ec25c8_d97e_df23_bc81_4d6ff2189930_MD0003_00 This patient has headaches and optic disc edema most likely due to idiopathic intracranial hypertension (IIH), a disorder in which increased intracranial pressure (ICP) occurs without a secondary cause. IIH is most common in obese (BMI ≥30 kg/m²) women of childbearing age, and although pregnancy by itself is not a risk factor, excessive weight gain (as in this patient) can exacerbate the disorder. ² Patients typically have positional headaches that are worse when lying flat, which increases ICP, and improve with sitting, which decreases ICP. Pulsatile tinnitus (due to increased vascular pulsations) and blurry vision (due to increased pressure on the optic nerves) also commonly occur. On physical examination, increased ICP can manifest as optic disc edema (ie, papilledema), abducens nerve (CN VI) palsy (lateral rectus palsy), and/or visual field deficits. Diagnosis is with neuroimaging followed by lumbar puncture, which reveals an elevated opening pressure (>250 mm H₂O). MRI of the brain, often with MR venography to rule out cerebral vein thrombosis, is the preferred imaging modality and avoids fetal radiation exposure. MRI is performed before lumbar puncture to exclude other causes of elevated ICP (eg, space-occupying mass) that would increase the risk of cerebral herniation (Choice B). (Choice A) A 24-hour urine collection can be used to diagnose preeclampsia (systolic blood pressure ≥140 or diastolic ≥90 mm Hg), which can cause headache and blurry vision in pregnant women. However, this patient's blood pressure is <140/90 mm Hg, and her trace urine protein is a normal pregnancy finding. (Choice D) Polysomnography can be used to diagnose obstructive sleep apnea (OSA), which is more common during pregnancy and in patients with obesity or rapid weight gain. OSA may be associated with morning headaches but not tinnitus or papilledema, making this diagnosis unlikely. (Choice E) Tonometry is used to evaluate for increased intraocular pressure, which can cause severe eye pain and headache if pressure changes acutely (eg, angle-closure glaucoma). In contrast, eye findings associated with IIH (eg, papilledema) are due to increased intracranial, not intraocular, pressure; therefore, tonometry is not used for evaluation. Educational objective: Idiopathic intracranial hypertension is most common in obese women of childbearing age and can present with positional headaches, pulsatile tinnitus, and papilledema. Diagnosis is with MRI of the brain followed by lumbar puncture. References: Idiopathic intracranial hypertension (pseudotumor cerebri): recognition, treatment, and ongoing management. (http://www.ncbi.nlm.nih.gov/pubmed/23136035) Idiopathic intracranial hypertension and pregnancy. (http://www.ncbi.nlm.nih.gov/pubmed/23563883)

A 17-Year-Old Primigravida at 29 Weeks Gestation Comes to the Clinic