Can an over Tight Platysmal Transection Be Released?

I'm sorry for your discomfort.

Have you tried noninvasive modalities such as massage and ultrasound?  You might find some minor relief with these options.

Unfortunately, at 5 yrs out, the problem is pretty well healed in place.

Releasing the platysma attachment to the mastoid might help with the tightness but probably not change the appearance.  If the platysma was also tightened in the submental area it could be relaxed at that point.

Good luck.

 IMHO, the chocking sensation is more likely caused by platysmal plication below the chin (over the larynx) than the mastiod area.  These are standard parts of every formal neck lift and the sensation typically is mild, lasting only a day or so.  Permanent sutures may have been used for the neck plication and may be cut and removed.  This would most likely cause those muscles to relax eliminating the chocking sensation.  

 There is another possibility.  Some surgeons use a long suture that goes from the mastoid, on one side of the neck, across and under the chin to the other mastoid creating a closeline effect which causes a chocking sensation.  You may want to have the surgeon clarify the plication technique as the latter is easilly released by cutting the suture at the mastoid on one side of the neck.  Hope this helps.