He already suffered from impaired sight and hearing, following an accident as a young child.
Adam was arrested for violent acts at a protest and accused of 'sending texts', according to Reprieve.
But activists claims a 'forced statement' was used as the sole piece of evidence against him in a secretive trial at the Specialised Criminal Court.
Reprieve said it had urged Trump to use his visit this month to raise the cases of protesters who face the death penalty.
But director Maya Foa claimed that by failing to raise the human rights issue, the Trump administration had effectively 'emboldened' the Kingdom to continue its clampdown on demonstrators.
Foa added: 'The Trump Administration must now urgently stand up for American values - they must call for the release of Munir, and all others who face execution for simply exercising freedom of expression.'