Case Presentation: An 8 year-old male presented with one week of acute ataxia. Physical exam was significant for a wide-based gait and a mild left sixth nerve palsy. A lumbar puncture (LP) was performed and revealed an opening pressure >35 cm H2O. After the elevated opening pressure was found, a dilated funduscopic exam was performed that revealed mild bilateral papilledema. The CSF from the LP was clear and colorless with <1 nucleated cell per µL, 3 RBCs per µL, glucose of 56 mg/dL and protein of 19 mg/dL. No organisms were noted on gram stain. CSF was sent for culture, EBV PCR, HSV PCR, enterovirus PCR, CMV PCR, West Nile PCR, anaplasma PCR, and VDRL, all of which were negative. Serum was sent for Lyme IgM/IgG, CMV IgM/IgG, anaplasma IgM/IgG, E. chaffensis IgM/IgG, mycoplasma IgM/IgG, West Nile IgM, EBV nuclear antibody, RPR, HIV, and a serum toxicology screen all of which were negative. A CBC, CMP, TSH, free T4, ESR, CRP, ANA, vitamin A level, and a folate level were all with normal limits. A non-contrast MRI and MRV were unremarkable. Routine electroencephalography was normal as well.  Based on the normal CSF findings, negative infectious and autoimmune workup, elevated opening pressure, and normal brain imaging, the patient was diagnosed with idiopathic intracranial hypertension (IIH). The patient was placed on acetazolamide and his gait abnormalities improved over the course of several months.

Discussion: IIH can be a difficult diagnosis in children, especially younger children, for several reasons. Firstly, to have a high index of suspicion for IIH, a practitioner requires a clear history of symptoms and thorough examination. Pre-pubescent children may not be able to articulate many of the classic symptoms of IIH (headache, visual obscurations, pulsatile tinnitus, etc.) and may not cooperate in a full physical exam, including gait assessment, making the diagnosis more challenging. The literature shows that pre-pubescent children are more likely to present with cranial nerve palsies and less likely to complain of headache in comparison to older patients. Cases of IIH presenting with ataxia have been reported in the adult literature, but there are no reports of this presentation in the pediatric population. Ataxia likely represents an under-reported physical finding of IIH that should raise suspicion for this diagnosis in both children and adults.  There is a lack of literature documenting the LP practices of pediatric hospitalists and emergency medicine providers and, thus, it is difficult to estimate how many diagnoses of IIH are potentially missed or delayed by not obtaining an opening pressure. In this particular case, the funduscopic exam, which revealed papilledema, was only obtained after the opening pressure was noted to be elevated on LP. If an opening pressure had not been obtained with the initial LP, the diagnosis of IIH likely would have been missed.

Conclusions: An LP with opening pressure should be performed routinely on all children presenting with acute ataxia or other signs of increased intracranial pressure, unless there is a compelling reason not to perform this procedure. Future studies investigating the LP practices of providers may be helpful to ensure that opening pressures are being obtained consistently in this patient population. This will serve to help prevent the irreversible visual deficits that can be associated with late or undiagnosed IIH.