This article shows the ED rates following priaprism including those of shorter duration.
http://www.meds … rticle/512953_3
This is taken from another thread and was posted by penissmith /forum/printthr … 95&page=5&pp=15
Megalophallus has been previously reported, but it is not generally recognized as a sequela of priapism. In our patient, this complication developed immediately after a prolonged and intense episode of priapism 9 years before the patient presented to us. This sequela did not interfere with subsequent erections. Fibrosis of the corpora cavernosa, as previously hypothesized,  should result in low flow by Doppler imaging. The reverse was true in our patient.
We propose an alternative mechanism for this sequela. The increase in penile circumference follows a sudden and permanent loss of elasticity of the tunica albuginea, brought about by a particularly intense priapism and a very engorged organ. The loss of elasticity of the tunica albuginea releases constraints on the corpora cavernosa, which then expand like a sponge. This expansion, helped by some subtunical venous impairment that is secondary to the remaining elasticity of the stretched tunica, results in pooled, deoxygenated blood in the corpora cavernosa consistent with our BOLD-MRI findings. BOLD-MRI defines the presence of deoxygenated blood, eliminating the need for an invasive procedure.
The plausibility of this mechanism for megalophallus is supported by the lack of increase in the circumference of the glans in our patient and the one previously described. The glans penis sinusoids are larger and the tunica albuginea is absent, and thus do not provide the bases for the pathologic features observed. The decreased elastic compression of the tunica explains the lack of pain despite the enlargement of the penis. The residual elastic restraint to expansion produces moderate blood stasis, explaining our BOLD-MRI findings. Finally, conservation of the capacity for full erection is due to the intactness of the corpora cavernosa and the infratunica venule system.”
1) Megaphallus developed immediately after a long and intense priapism.
2) The size of the glans didn’t increase.
3) The pooled blood strongly suggests that the tunica is permanently expanded.
If there was massive cell growth of the smooth muscle, it would take awhile to develop and the glans should have grown as well.