Head and Neck Pain, Syncopal Episode, Abnormal Cerebrospinal Fluid, and Hyponatremia in a Middle-Aged Woman

1. Important clinical information includes neck pain, the absence of fever or focal neurologic signs, and syncopal episode. The most striking laboratory findings include the abnormal chemical and cytologic analysis of the cerebrospinal fluid (CSF) sample (hypoglycorrhachia, proteinorrhachia, and pleocytosis) and mild hyperglycemia. 2. Hypoglycorrhachia: The CSF is normally a clear, colorless, and virtually acellular fluid that is actively produced by the choroid plexus and ependymal cells lining the central nervous system (CNS) ventricles and subarachnoidal space through a process of ultrafiltration of plasma. Glucose levels in the CSF are 60% to 70% those of the serum; therefore, comparison between both values is paramount in interpreting abnormal results. Increased CSF glucose (hyperglycorrhachia) may be seen in the context of hyperglycemia or be due to a traumatic tap. Conversely, decreased CSF glucose (hypoglycorrhachia) is commonly found in untreated bacterial, fungal, tuberculous, or amoebic meningitis, and rarely in some viral CNS infections (particulary those caused by mumps and lymphocytic choriomeningitis viruses). Other causes of hypoglycorrhachia include CNS sarcoidosis and neoplasms (primary or metastatic). Proteinorrhachia: The normal CSF protein level is about 1% of the serum protein level. Increased levels are seen with most infections involving the meninges and the CNS, but are Clinical History