How To Treat Difficulty In Speech After Head Injury?

With immense sorrow, I am briefing this that my brother's son aged 16 years met with an accident on 24.04.2010 and have head injury and in critical condition. Operation have already done and in the first stage put him in ventilator and now in ICU. There is some sign of relief that now he is started to identify the people but not able to speak now even after 23 days. Can he improve from this stage, or please let us know where we get best treatment for this.