Flight Crew Air Transport Pilot (ATP)
Deviation / Discrepancy - Procedural Clearance; Flight Deck / Cabin / Aircraft Event Illness / Injury; Inflight Event / Encounter Other / Unknown
Flight Crew Diverted
Human Factors
During cruise flight while en route from ZZZ to ZZZ1 just abeam ZZZ2 we heard a outburst and panic from behind us. We turned to find a passenger in distress and declaring that he was experiencing uncontrollable cramping and he couldn't control or feel his legs or arms and couldn't un-clench his fists. He begged for water and we provided him with water and asked if he was doing ok. My First Officer continued to monitor the passengers conditions as the rapidly deteriorated we observed the passenger going in and out of consciousness and became unresponsive and seemed to stop breathing multiple times. We notified ARTCC but was not met with a response from ATC. We were struggling to gain contact with ATC and advised them of our intentions to divert to ZZZ2 the closest airport and land immediately for a passenger medical emergency. This request was relayed with company aircraft as we were in a communications blackout zone. We transferred controls and I advised dispatch; an ambulance met us on the airfield. Once landing safely on the field we transferred the passenger to the ambulance paramedics. We called Operations Center; and made a maintenance log write up for the aircraft due to the passenger soiling the seat. The aircraft received maintenance and the passenger was taken to the local hospital. Passenger medical conditions; potential pre-existing medical conditions. Complications with asthma/ heatstroke/  panic attack.
Small Transport pilot reported a passenger medical situation inflight.