Titanium mesh is a commonly used material for cranioplasty. While it is a safe and highly biocompatable material, it can modify the presentation of post-operative complications. This case report details 3 patients (2 recurrent meningiomas and an extradural haematoma) in whom post-operative complications, although not caused by the titanium mesh, were modified in their presentation by the permeability of the material. The permeable nature of the mesh allows intracranial pathological processes to extend extracranially and vice versa.