Neuromuscular dysfunction.

Patientswith advancedcancerfrequently complain of fatigue and generalizedweakness, oftenmuscular in nature. There are several wellknown syndromesdemonstratingthe remoteeffectsof canceronneuromuscular function.’ Patientswith either dermatomyositisor polymyositishave five to seventimes the incidenceof malignancy comparedto the general population.Clinically, thissyndromeis characterizedby agradual progressive muscularweaknessoccurring over a periodof weeksto months.Theweaknesseventuallystabilizes, is usually notdisabling,andusuallyinvolvesthe proximal muscles.In the majority of cases, themyopathyandcancer present within one year of eachother. The myasthenic syndrome(Eaton-Lambert) is anotherclassicexampleof a cancer,mostoftensmallcellcarcinoma of the lung, producing a remoteor paraneoplastic effectontheneuromuscular system. This myasthenic syndromeis characterizedby muscle weaknessandfatigue,which aremost pronouncedin the pelvic girdle and thigh. Othercommonfeaturesinclude drynessof the mouth, dysphagia, dysarthriaandperipheralparesthesias. Successful treatmentof theunderlying smallcelllungcancercanproduceimprovementin themuscularsymptoms. Finally, the associationof myasthenia gravis and thymoma is well established.Patientswithmyastheniagravis presentwith muscularweaknessespecially in theocularandcranialmuscles. Thereis atendencyfor fluctuationand partial reversibility by cholinergic drugs.A numberof tumorsincluding lymphomas,pancreas, breast,prostate, ovary, thyroid, cervix, kidney, rectum andpalatehavebeendescribedin associationwith myastheniagravis,but most authors concludethat the incidenceis thesameasthatexpectedin thenonnalpopulation. Given this background,two recent publicationsshed further light on the relationshipbetweencancerand neuromuscular dysfunction.2’3 Brueraetal,2fromtheCrossCancer Institute,Edmonton,Canada, prospectively studied61 consecutivepatients with advancedbreastcancerto assess muscleelectrophysiology.This group ofpatientswascomparedto 20 nonnal ageandsex-matchedfemalecontrols. Nutritional status,lean body mass, voluntary and involuntary muscle electrophysiologytestsof theadductor pollicis, and ultrasonographicmeasurement of thetricepsbrachialis,sternomastoidand adductorpollicis muscleswere determinedin patients andcontrols.Patientswith breastcancerwerechosenbecause in thispopulation the incidenceof malnutrition is significantly lower thanpatientswith other cancerssuch as lung or gastrointestinal. Malnutritionalonehas beenreportedas a causeof abnormal muscle electrophysiology.The funcCommentary on contemporary care of patientswith advanced cancer