FIGURE 122.5 T2-weighted sagittal MRI of the cervical and thoracic spine demonstrates a heterogeneous epidural hematoma causing compression of the cervicothoracic junction Normal thecal sac morphology can be seen cranial and caudal to the lesion CENTRAL NERVOUS SYSTEM INFECTION Meningitis Meningitis is an infection of the leptomeninges (pia, dura matter, arachnoid) and thus of the subarachnoid space This space is continuous from the hemispheric convexities to the lumbosacral subarachnoid space (see Chapter 94 Infectious Disease Emergencies )