The 19-year-old suffered a terrible leg injury in the first half as Rudi Garcia's side were forced to settle for a point yet again in Serie A.
The Giallorossi were forced to settle for a fourth Serie A stalemate in a row in a game of few clear-cut chances in Verona, in a game which saw 19-year-old Mattiello forced off with a suspected broken leg.
Juan Iturbe spurned Roma's best chance of the opening stages as he blazed over the crossbar after being teed up by Gervinho.
Mattiello was forced off midway through the first half following a challenge with Radja Nainggolan, and the incident seemed to affect both sides as the tempo ebbed out of the game.
The 19-year-old stretched for the ball in a 50-50 with Nainggolan and his right leg bent as his foot became caught beneath the Belgian, who had met the ball fairly. Matiello was then carried off on a stretcher, his leg in a brace.
Gervinho missed the clearest opportunity of the half just a few minutes before the break. Iturbe turned provider this time as he slipped the Ivorian through, but his right-footed shot from inside the box was angled just wide of the far post.
Alberto Paloschi then headed over from the center of the box when he really should have done better, but the scores remained level heading into the break.
Another strong run from Gervinho 10 minutes into the second half allowed Ashley Cole a stab at goal but he was quickly closed down, before Iturbe lashed over again from 20 yards after a good passing move.
Roma continued to dominate possession but struggled to find a way through a rigid Chievo rearguard as the home side pulled more men behind the ball and prepared to counter. One such break saw substitute Riccardo Meggiorini cut inside and fire low but Morgan De Sanctis held well.
Adem Ljajic fired over a free kick from distance before another Gervinho-led attack broke down on the edge of the area, but Roma was unable to fashion an opening as the club slipped to a fourth draw on the bounce in the league and gave Juventus the chance to increase its advantage when it faces Sassuolo on Monday.