McParland was sent from the dugout in the first half by referee Nigel Miller after complaining about Shrewsbury's opener from the spot.
After on loan youngster Krystian Pearce drew Notts level with his first senior goal, second-half substitute Neil MacKenzie stole victory with a stunning free-kick 15 minutes from time.
In the opening period both sides saw chances cleared off the line it was the visitors who went in at half-time ahead.
County captain Adam Tann brought down Shrews striker Dave Hibbert in the box on 39 minutes and the frontman picked himself up to score his eighth goal of the campaign.
Gary Peters' men looked on course for a first away win since early November, before Notts burst into life through Pearce's equaliser.
Tann headed MacKenzie's corner back across goal and they 17-year-old Birmingham City loanee forced keeper Glyn Garner into a good save before following up with a volley into the roof of the net.
The visitors responded immediately and skipper Stewart Drummond put a diving header over a few minutes later before a rejuvenated Notts took control.
Lawrie Dudfield was brought down on the edge of the box and MacKenzie clinched the points from 20 yards by firing his free-kick over the ball and into the top corner.
Afterwards McParland said: "It was a great view from up in the stands and it's amazing what you can see from so high up.
"I wasn't impressed with our first-half performance, we still got a lot of things wrong but there was a big relief on the final whistle."
Shewsbury boss Peters added: "I though our first-half performance was the best we've had all season but we were punished for not taking our chances.
"We conceded a sloppy corner and then gave away a silly free-kick."