Aseptic Meningitis

Today's case involved a 52-year-old man with a past medical history of type 1 diabetes mellitus on insulin pump and dyslipidemia who presented to hospital with a 10-day history of hemicranial headache.  He also had some mild alterations in mental status, diplopia, blurred vision, and nausea.  His initial physical examination was normal, but evolved to feature a possible abducens palsy as well as some ptosis.  His neuroimaging (MRI) was normal.  He went on to have a lumbar puncture which showed a normal opening pressure and a pleiocytosis (88 WBC, all lymphocytes) as well as elevated protein.  Viral and infectious tests are pending at this point.  It was further revealed that he may have had some mosquito exposures as well as having spent some time in Vermont and Vancouver.

Learning points:

-We discussed the differential diagnosis of headache which I like to break down into “Red Flag” features or the absence of red flag features.  These are things like focal neurologic deficits, thunderclap headache (maximal intensity reached within one minute), signs of raised intracranial pressure, visual deficits, altered mentation, fever, age, or worsening frequency/intensity with other medical conditions.

-Further than that, headaches can be broken down into primary headache disorders (migraine, tension, cluster) and headaches secondary to other problems (infections, vascular phenomena, raised intracranial pressure, and mass effects).

-We discussed the differential diagnosis to a unilateral ptosis which includes problems with the sympathetic chain (Horner’s syndrome), problems with the third cranial nerve (pupil-sparing lesions such as ischemic injuries and non-pupil-sparing such as compressive lesions), neuromuscular problems, and central nervous system/nucleus problems

-We discussed Lyme disease and its propensity to cause an aseptic meningitis picture, along with other infections such as West Nile Virus (which can produce a host of neurologic syndromes), and HIV acute seroconversion illness

-We discussed some of the infections that diabetic patients get that we do not typically see in non-diabetic patients including malignant otitis externa, emphysematous pyelonephritis and emphysematous cholecystitis

Further Reading:

Lee, B. E., & Davies, H. D. (2007). Aseptic meningitis. Current opinion in infectious diseases, 20(3), 272-277.