CSF albumin and immunoglobulin analyses in childhood neurologic disorders

OBJECTIVE: To evaluate the utility of qualitative and quantitative analyses of CSF immunoglobulins as part of the diagnostic workup of CNS inflammatory conditions. METHODS: One hundred eighty-nine children who underwent CSF investigation for their neurologic condition had CSF and serum testing to (1) qualitatively identify oligoclonal band (OCB) patterns and (2) quantitatively measure the immunoglobulin (Ig) G index and albumin quotient (Q(Alb)). Case notes were retrospectively reviewed and patients were grouped according to whether their primary diagnosis was due to an inflammatory (n = 104) or noninflammatory (n = 85) etiology. RESULTS: CSF-restricted OCBs were found in 20/104 (19%) of the inflammatory group compared with 4/85 (5%) of the noninflammatory group (p= 0.0036). Mirrored OCBs were found in 13/104 (12.5%) of the inflammatory group compared with 5/85 (6%) of the noninflammatory group (p = 0.14). IgG index and Q(Alb) were significantly higher in patients with an inflammatory etiology. However, a raised IgG index (>0.85) and Q(Alb) (>0.049) were seen in both groups, with Q(Alb) abnormalities seen more frequently in the inflammatory group (p = 0.0028). CONCLUSIONS: Both methods were informative in identifying inflammatory mechanisms. Abnormalities were more commonly, but not exclusively, seen in primary inflammatory conditions. The qualitative and quantitative evaluation collectively revealed additional positive results than when done in isolation.