76 NEUROLOGIC PARANEOPLASTIC SYNDROMES
Harrison’s Manual of Medicine
NEUROLOGIC PARANEOPLASTIC SYNDROMES
Varied neurologic disorders occur in pts with systemic neoplasia (Table 76-1). Paraneoplastic syndromes are those related to a remotely located neoplasm; they often evolve over days to weeks and may precede detection of neoplasm by months or even years. Recognition of a distinctive paraneoplastic syndrome should prompt a search for cancer, although these disorders also occur without cancer (idiopathic). Diagnosis is based upon the clinical pattern (Table 76-2), exclusion of other cancer-related disorders, confirmatory serum or CSF antibodies, or electrodiagnostic testing. Tumors most often associated are cancers of lung, stomach, breast, ovary, and colon, but neurologic disorders occur with 1 in 6 ovarian tumors and 1 in 7 lung tumors. One postulated mechanism is an autoimmune response directed against common antigenic determinants expressed by tumor and neural cells; demonstrated in Lambert-Eaton myasthenic syndrome (antibodies to presynaptic calcium channels and associated proteins) and myasthenia gravis (antibodies to postsynaptic acetylcholine receptors). Known autoantibodies are associated with a number of paraneoplastic syndromes (Table 101-3, p. 641, in HPIM-15). Treatment is difficult, usually unsuccessful. Resection of underlying tumor is usually ineffective, but isolated reports of improvement exist. Immunosuppression is generally without benefit, although plasma exchange or immunosuppression has been used successfully to treat Lambert-Eaton syndrome or myasthenia gravis.
Table 76-1 Effects of Malignancy on the Nervous System
Table 76-2 Neurologic Paraneoplastic Syndromes
For a more detailed discussion, see Al-lozi MT, Pestronk A: Paraneoplastic Neurologic Syndromes, Chap. 101, p. 636, in HPIM-15.