Question: Notes indicate that the patient had “charley horse l calf.” Are there any specific — or for that matter nonspecific — ICD-10 codes for “charley horses”? Illinois Subscriber Answer: Oddly enough, there is a diagnosis code for charley horse specific to the calf. Report M62.831 (Muscle spasm of calf) for the encounter. The code doesn’t break out into laterality, so you won’t be able to specify that it was the patient’s right calf. All in the family: The charley horse code is part of the M62.83- (Muscle spasm) code set, which includes these codes: