Dear heidimills
you might be dealing with a case of dystonia? how old is this patient? any history of stroke?
If you sure it is spasm, maybe trying some antispasmodics before mobilization may help ...or botox injections...
if treatments and investigations to the shoulder and neck are coming to not..then my first thought is a dystonic arm...
any radiological examinations for the neck? you could send him for a head/neck MRI...in the meantime, any neuro signs suggesting an upper motor neuron problem...?ie...reflexes? sensation? muscle power? stereognosis? associated reactions?does position reduce the tone in the upperlimb? what happens with passive movement? any other associated symptoms?...any family history of this problem? what happens with active movements in the limb?
cheers