A subset of fibromyalgia patients with findings suggestive of chronic inflammatory demyelinating polyneuropathy (CIDP) respond to intravenous immunoglobulin (IVIg).
Xavier J. Caro and Earl F. Winter.

PURPOSE:  We have previously described a demyelinating CIDP-like illness in a subset of FMS patients.  CIDP is thought to be immune mediated and is known to respond to IVIg.  We attempted, therefore, to treat these FMS/CIDP-like patients with IVIg in an open label fashion.  The results of our experience are reported here. 

METHODS:  Forty-nine of 58 consecutive patients with FMS were screened for elctrodiagnositc (EDX) evidence of demyelination.  Of these, 23 had EDX evidence suggestive of CIDP, i.e., demyelination in two or more peripheral nerves.  Fifteen of these 23 patients met eligibility criteria for IVIg treatment.  Eligibility required an absence of another explanation for demyelination, normal cardiovascular, renal, and hepatic status, detectable serum IgA, vascular accessibility, and an ability to give informed consent.  Each  subject received IVIg 2 gms/kg over 5 days.  Per published guidelines, each patient received a single IM dose of methylprednisilone acetate 1 week prior to IVIg   to lessen side effects.  All other medications were maintained unchanged.  Each patient underwent clinical reassessment 2 to 4 weeks after infusion.

RESULTS: No significant adverse effects of IVIg were seen.     

CONCLUSION:  A subset of FMS patients who have a CIDP-like component to their disorder appear to respond favorably to IVIg. This novel therapeutic approach deserves further study in this subset of FMS patients.

CLINICAL OUTCOME OF IVIg THERAPY IN FMS/CIDP-LIKE PATIENTS
CLINICAL MARKER	PREINFUSION	POSTINFUSION	pVALUE
Subjective: Pain (0-10)	6.8 (+2.3 SD)	4.4 (+2.0 SD)	0.005
Subjective: Fatigue (0-1)	0.6 (+0.5)	0.4 (+0.5)	N.S.
Subjective: Stiffness (0-480 MIN)	216 (+211)	192 (+226)	N.S.
Objective: Tenderness (0-3)	1.8 (+0.68)	0.76 (+0.55)	0.006
Objective: Strength (0-9)	7.7 (+0.80)	8.3 (+0.67)	0.02

 Presented at the
American College of Rheumatology
Annual Scientific Meeting
San Antonio, TX – Oct 16 – 21, 2004