SSR 99-2p, 64 Fed. Reg. at 23381. The ruling instructs that, before rejecting a claim based on CFS, the ALJ must first consider the medical evidence and evaluate the condition as any other unlisted impairment. Therefore, the CFS claim is analyzed under the same five step framework applied to every social security disability claim. See 20 C.F.R. S 416.920.
The five step analysis begins with the question of whether the claimant engaged in substantial gainful employment. 20 C.F.R. S 404.1520(b). If not, the analysis continues to determine whether, based upon the medical evidence, the claimant has a severe impairment. 20 C.F.R. S 404.1520(c). If the claimed impairment is sufficiently severe, the third step considers whether the claimant has an impairment that equals or exceeds in severity one or more of the impairments listed in Appendix I of the regulations. 20 C.F.R. S 404.1520(d); 20 C.F.R. Part 404, subpart P, App.I. If so the claimant is disabled. If not, the next inquiry considers if the impairment prevents the claimant from returning to past work. 20 C.F.R. S 404.1520(e); 20 C.F.R. S 404.1545(a). If the answer is in the affirmative, the final consideration looks to whether the impairment precludes the claimant from performing other work. 20 C.F.R. S 404.1520(f).
... the Commissioner recognizes that "no specific etiology or pathology has yet been established for CFS." SSR 99-2p, 64 Fed. Reg. at 23381. Still, the Commissioner's directive in SSR 99-2p explicitly requires a CFS disability claim to be accompanied by medical signs or laboratory findings. SSR 99-2p, 64 Fed. Reg. at 23381. Recognized examples of medical signs, clinically documented over a period of at least 6 consecutive months, that will establish the existence of a medically determinable impairment include: palpably swollen or tender lymph nodes on physical examination; nonexudative pharyngitis; persistent, reproducible muscle tenderness on repeated examinations or any other medical signs that are consistent with medically accepted clinical practice and are consistent with the other evidence in the case record. SSR 99-2p, 64 Fed. Reg. at 23382.