ASIA is commonly used, however difficult to grade a muscle when it is spastic. Measures like FMA, Brunnstrome stages are available for cerebral lesions. They may not be appropriate here due to difference in pathology behind movement deficit.
I don't know there to be a scale in chronic SCI that perfectly accounts for spasticity.
In the absence of a contracture, ASIA should still work reasonably well for chronic, spastic plegia because the spastic muscles with less than 3/5 strength would likely be impaired after the acute injury and prior to the onset of UMN signs. Though this underscores why it's important to obtain ASIA within 72 hours after injury, and again at admission/discharge from rehabilitation.
A good study would be to compare ASIA scores on discharge from rehabilitation with ASIA scores years out accounting for spasticity on the modified Ashworth scale. I'm not aware of such a study but someone else may know of one.
Thank you Sean Robinson, my query is about measure which can quantify motor control after spinal cord injury similar to those for lesion of brain, eg. FMA, STREAM
I would encourage you to do a search on rehabmeasures.org If you entered the search term spinal cord injury - the site will come up with researched outcome measures and give you the validity, cut off scores etc.