northampton have ruled out winger george north for the game against clermont auvergne on saturday .
he will see a neurosurgeon following a third serious head injury in two months .
the 22-year-old was recently knocked unconscious when struck by the knee of wasps no 8 nathan hughes .
jim malinder , nothampton 's director of rugby , wants the club to act in the best interests of north 's long-term health .