**3. Clinical features**

The symptoms and signs of patients with DIPG occur secondary to the involvement of different parts of the brainstem, which include the midbrain, pons and medulla. The brainstem serves as a conduit through which axonal tracts pass to the spinal cord, cerebrum or exit as cranial nerves. Due to the diffuse nature of DIPG, the tumor infiltrates the white matter affecting the adjacent cranial nerves and white matter tracts [11]. As the pons contains important nuclei critical for life-sustaining function, any damage caused by the tumor or its treatment has devastating effects. DIPG predominantly occurs in in the middle childhood. Median age at diagnosis is 6–7 years, with males and females affected equally [11–13]. Interestingly, adults with DIPG tend to have a longer survival which may indicate a less aggressive and biologically different tumor from that in children [14]. Typically, the presentation is with neurological symptoms of less than 3 months duration [15] with the "classic" triad of cranial nerve deficits (diplopia and facial asymmetry), long tract signs (hyperreflexia, clonus, upward Babinski, increased tone and decreased strength) and cerebellar signs (ataxia, dysmetria and dysarthria), which is seen in about 50% patients [16, 17]. In most cases, abducens nerve palsy is the earliest sign and is a sensitive predictor for DIPG [17]. Obstructive hydrocephalus with signs of raised intracranial pressure are seen in <10% of patients [18]. Other symptoms for example behavioral changes, night terrors, and school difficulties may also occur.
