A 7-year-old female with no history of neurological or behavioral disease presented to the emergency department for 2 days of transient vertiginous episodes that affected her ability to walk and resulted in vomiting. These episodes lasted only minutes at a time and occurred predominantly in the morning, shortly after waking up. This acute presentation followed a 2-week course of waxing and waning fever with headaches. Prior to presentation at our emergency department, the patient was seen by an outpatient provider for her fever, where a SARS-nCoV-2 nasopharyngeal PCR test was negative. History was significant for multiple exposures, including multiple tick bites over the past month (with at least 1 that lasted >48 hours), freshwater swimming, and both parents with a recent history of fever and headache preceding the onset of the patient's febrile symptoms. This occurred amidst the SARS-nCoV-2 outbreak in the United States.
Initial examination in the evening revealed an afebrile patient without lymphadenopathy or rash. Neurological examination was normal, including intact extraocular movements without inducible vertigo or nystagmus, no ataxia or dysmetria, and negative Romberg sign. Both Kernig and Brudzinski maneuvers were normal. Fundoscopic exam did not show swelling of the optic discs. Intake labs demonstrated elevated transaminases with an AST of 141 and ALT of 268, elevated absolute reactive lymphocyte count to 0.1 k/microL, and white blood cell count 8.37 k/microL. Repeat SARS-nCoV-2 PCR testing was negative. Non-contrast CT of the head did not show acute intracranial pathology.
The patient was admitted for observation given her history and lab abnormalities. The next morning on repeat neurologic examination, during assessment of gait the patient abruptly sat on the floor with complaints of "dizziness" and described a tumbling rotation of her surroundings. During the episode, fixed gaze elicited conjugate downbeat nystagmus. She then had an episode of emesis, and her symptoms spontaneously resolved over the next half hour.
Our differential for new onset episodic downbeat nystagmus included central processes affecting the cerebellum and brainstem including structural disturbances (such as space occupying lesions, cervicomedullary malformations, cerebellar degeneration, and episodic ataxias), infectious and/or toxic encephalitides, and cerebellar stroke. The history of outdoor activities and prolonged tick exposure raised suspicion for locally endemic arthropod-borne encephalitis. Subsequent work-up included magnetic resonance imaging with and without contrast, magnetic resonance angiography, and cerebrospinal fluid analysis with cytopathology and infectious work-up.
Contrast-enhanced magnetic resonance imaging of the brain revealed diffuse leptomeningeal enhancement and parenchymal enhancement affecting the inferior cerebellar folia (Figure 1). Same-day cerebrospinal fluid studies (collected following imaging) demonstrated elevated protein, but otherwise had a negative PCR panel for common causes of meningoencephalitis (not including Epstein-Barr virus) (Table 1). As the patient was afebrile and clinically improving without further episodes, she was discharged on an empiric short course of doxycycline with cerebrospinal and serum antibodies pending (Table 1).
Cerebrospinal fluid cytopathology showed lymphocytic pleocytosis and results of infectious work-up found serum Epstein-Barr virus IgM and IgG positivity (Table 1), confirming the diagnosis of Epstein-Barr virus meningitis. The doxycycline was discontinued, and the patient had resolution of her symptoms without other treatments.