The `Lethal Weapon` star - who is currently under investigation after being accused of domestic abuse by the Russian singer during an alleged violent row on January 6 - has stated in court documents that his former partner has a history of self harming.
According to a declaration that was filed with Los Angeles Superior Court and obtained by gossip website TMZ, Mel said: "Oksana is emotionally unstable and suffers from Trichotillomania, an impulse control disorder characterised by the repeated urge to pull, and pulling, out one`s own hair, eyelashes, eyebrows and other body hair.
"During our relationship Oksana often had scratches and bald spots on the side of her head as a result of this disorder (scratches she is now, apparently, attempting to blame on me!)."
Although Mel has admitted to slapping Oksana during the fight, he denies any other physical violence including knocking out two of her teeth.
However Oksana`s lawyer Dan Horowitz, insists Mel`s claims his client harmed herself are false.
He said: "I`ve spent over 100 hours with Oksana and I have never seen her pick her hair or scratch her skin. She just acts like a totally normal person."
Meanwhile, another dispute between the former couple - who have 12-month-old daughter Lucia together - has reportedly broken out, with Oksana questioning the `Braveheart` star`s financial worth.
Mel - who has been ordered by a judge to pay $20,000 a month child support for Lucia - says he made $7.2 million between August 2009 and 2010, but Oksana claims the 54-year-old star told her he made $40 million in 2009.
Judge Gordon, presiding over the case, said Mel`s exact worth is important in establishing how much he should pay for Lucia.
He said: "Although petitioner argues at length about what the needs of the minor child might be, Petitioner avoids the issue of his station in life and how his extraordinary high income might affect the reasonable needs of the minor child."
Oksana has also seen changes in her legal team, with Alan Shifman, her family law attorney, leaving the case to be replaced by Ronald A. Litz.