Birds of Paradise's artistic director, Robert Softley Gale says in his programme note that he knew the old unwritten rule: as an artist with a disability you can't create work focussing too much on your own impairment. But he did it anyway, and the result is a thoroughly original piece about cerebral palsy and manhood that gives the kind of insight, wit, challenge and wholeness that you sense could only come from a writer/director and cast with first-hand experiences of the condition. (Softley Gale plays on this later but to say how would be to spoil one of the show's twists).

Performed by four men – Colin Young, Laurence Clark, Pete Edwards and Philip Ryan – it's a piece that reaches into many spaces, intersecting masculinity and disability, humour and grace, vulgar machismo and soulful sensitivity, anarchy and structure, fiction and autobiography. The choreography and script are underscored by a live soundtrack from composer Scott Twynholm and musician Jill O'Sullivan that shifts from ponderous electro-chords to graceful songs about manhood and floating in space.

Performer and BSL interpreter Amy Cheskin is there not simply to repeat what the male performers are saying but to flit in and out of the action, treading a line between BSL speech and dance, sometimes taking the role of girlfriend sometimes watchful bystander.

Meanwhile, at the heart of the action the men use the movements of CP in dance and deliver ribald anecdotes peppered with smutty language (non-deaf audience members will learn BSL for 'fuck' very quickly), covering dating, parenthood, masturbation, work, and condescending able-bodied women.

Softley Gale is particularly sharp on picking apart the codes that govern heteronormative masculinity. At one point these are sent up in a glorious game of one-upmanship that turns into chaos as the cast all compete to identify themselves as the smartest, most handsome, one with the biggest car, biggest dick etc; a leveller of a rammy every bit as idiotic for disabled men as it is for non-disabled.

But the shifts in tone are perfectly placed, and as soon as we think we have a grip on the piece, Softley Gale rips the rug out from under us. Invited to laugh with the performers as they laugh at themselves, they then take turns to patiently explain that this is a tactic used to make able-bodied people feel more comfortable.

Later Pete Edwards' solo, rolling on a leather mat on the ground, filmed from above as he tells us about his relationship, is a gorgeous mix of freeform dance – allowing the body to speak its own language – and candid storytelling.

Then we are back in the world of the surreal: packaged sandwiches fall from the sky, the men try to rip into them, and what could have been simply a political statement inviting us to think about the everyday challenges of cerebral palsy also turns into a wondrous, messy, tactile carnival, as the performers smash and mush the bread and fillings into the stage.

This harnessing of multiple levels – provoking and celebrating – feels rare. And perhaps this is the sharpest thing about Purposeless Movements; that it firmly rejects being categorised. Rather than dance, theatre, physical theatre, stand-up, performance art, it refuses to be anything other than itself: a brilliant, brainy and beautiful piece that leaves you with generous answers as well as multiple questions.

Reviewed at Edinburgh Festival Theatre Studio. Until 24 Aug, times vary, £20.