<unk>  is a term used to describe thickening, inflammation, and scaring of the arachnoid membrane, which is the middle layer surrounding the central nervous system. These abnormalities may be self-limited or may cause compression of the nerve roots and spinal cord. Patients may report a variety of clinical symptoms, including severe back pain that persists at rest, perineal/saddle numbness, neurological deficits, skin rashes, and sympathetic or vascular changes.  The cause of<unk>  is unknown but may occur as a result of invasion (surgery), neuraxial injections, certain myelograms, infections, blood, a herniated disc, or tumors. Diagnosis is based on symptoms, and magnetic resonance imaging. Unfortunately, the treatment of<unk>  is difficult and limited and should focus on symptomatic management.
Arachnoiditis
Subdural empyema
Brain abscess
Cavernous sinus thrombosis
Subdural hematoma
Labyrinthitis
Migraine
Cerebral venous sinus thrombosis