Clinical case: Seizures and altered mental status in a young woman

We may have just posted an episode on the initial evaluation of a patient with altered mental status, and at least one prior episode on seizure management, so this clinical case is meant to build on these prior topics. In this week’s BrainWaves episode, Dr. Fima Macheret walks us through the case of a young woman with an unusual cause of seizures and delirium.

Case presentation

A 28 year-old African American woman was brought in to the ED by paramedics after having a witnessed convulsive seizure in her graduate school classroom. The paramedics report intermittent, whole body convulsions for 6 minutes prior to their arrival. Five mg of intravenous midazolam was administered in the field with cessation of seizure activity. In the emergency room, she is unresponsive but afebrile, pulse 112 and regular, blood pressure 168/91, respiratory rate of 10 and a normal pulse oximeter. A head CT was unremarkable. As she is being wheeled back to her room in the ED, she begins to moan.

Her sister, who is healthy, reports no personal or family history of seizures in your patient. No drugs or alcohol, no new medications, but she takes a daily multivitamin. Usually the patient and her sister talk on the phone every night, but for the last 2 days, the patient has been saying strange things and “not making sense.” But there were no other specific complaints from the patient during these phone calls.

At this point, Dr. Macheret discusses his approach to altered mental status for a patient with a seemingly progressive course. Things specifically to consider in a patient like this include toxic exposures, metabolic disturbances (hypo/hypernatremia, hypoglycemia, hypercalcemia, uremia, hyperammonemia), subclinical seizures, acute disseminated encephalomyelitis (usually in younger kids), meningoencephalitis, progressive intracranial hypertension (mass lesion[s], intraparenchymal hemorrhage, venous sinus thrombosis, etc.), and rarer things like acute intermittent porphyria, Hashimoto’s encephalopathy, and limbic encephalitis.

An appropriate initial battery for this patient would include:

  • Urine pregnancy test (for every woman of childbearing age!)
  • HIV (every person could use this screen)
  • CMP, CBC
  • Urinalysis, chest x-ray
  • MRI of the brain
  • Lumbar puncture to exclude inflammatory or infectious causes of encephalitis

Additional tests you could consider might be TSH and/or anti-TPO antibodies, a routine or 24hr EEG to exclude intermittent complex partial seizures, and a number of other tests.

Among the first line of diagnostics, her urine pregnancy test returns positive, and her urinalysis shows severe proteinuria (3.5 g/day) without any nitrites or leukocyte esterase. A lumbar puncture is remarkable for 29 white blood cells per HPF with a 78% neutrophilic pleocytosis, 3,500 red blood cells, a protein of 70 mg/dL and normal CSF glucose. (Is this abnormal??) Gram stain and culture and HSV PCR are sent.

Technically, the patient has eclampsiawhich is a rare, life-threatening condition faced by pregnant women and women who are recently post-partum. The management of eclampsia involves critical care monitoring (the ABC‘s), and treatment of seizures. Unlike nearly any other cause of seizure, eclampsia is best treated with intravenous magnesium sulfate to maintain serum levels between 4.8 and 8.4 mg/dL for the next 72 hours. Unfortunately, despite treatment with magnesium, antibiotics and antivirals for possible HSV encephalitis, the patient’s mental status fluctuates over the ensuing days. An MRI of the brain is eventually performed.

Axial FLAIR sequence of the patient’s MRI.

The MRI is consistent with subcortical white matter injury in the temporal and occipital regions which would be most concerning for posterior reversible encephalopathy, which is the neuroimaging correlate of eclampsia. It could also have represented ADEM or tumefactive multiple sclerosis if there were more enhancement, particularly if the lesions were ovoid and the enhancement were ring-like. Importantly, these are not typical features of an infectious meningoencephalitis or HSV encephalitis, autoimmune encephalitis, or many of the other conditions we had been considering. Alternative considerations like gliomatosis cerebri from a multifocal glioma, reversible cerebral vasoconstriction syndrome, osmotic demyelination, and progressive multifocal leukoencephalopathy can produce similar imaging findings in extreme cases, but one would not expect that in this otherwise healthy pregnant woman without any significant past medical history. Nevertheless a repeat MRI after several weeks would be helpful to confirm that this was PRES and not some new chronic inflammatory or infiltrative process.

HSV PCR from the CSF is negative, and the acyclovir was discontinued. Final CSF bacterial culture grew no bacteria. Blood cultures remained negative. Her blood pressure eventually normalized with the use of oral labetalol, and her mental status improved gradually over the next week. There were no recurrent seizures. Obviously, the pregnancy was managed by the obstetrics team with emergent caesarean delivery of the fetus, and the infant was immediately taken to the neonatal ICU for monitoring. Repeat MRI of the patient 2 weeks after delivery showed near complete resolution of the subcortical T2 changes seen on prior MRI.

The case is interesting because PRES is the radiographic equivalent of eclampsia, and there are many reasons as to why a patient who comes into your hospital altered could become altered for different reasons. Murphy’s law wins. So keep an eye out and your differential broad, even when you think you’ve cracked the case.

 

[Jim Siegler]


The content in this episode was approved by Dr. Fima Macheret.

REFERENCES

  1. Aagaard-Tillery KM and Belfort MA. Eclampsia: morbidity, mortality, and management. Clin Obstet Gynecol. 2005;48:12-23.
  2. Duley L, Henderson-Smart DJ, Walker GJ and Chou D. Magnesium sulphate versus diazepam for eclampsia. The Cochrane database of systematic reviews. 2010:CD000127.

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