====== Arachnoiditis ======

Inflammatory condition of the lumbar nerve roots. Actually a misnomer, since [[adhesive arachnoiditis]] is really an inflammatory process or [[fibrosis]] that involves all three meningeal layers (pia, arachnoid, and dura).

===== Localization =====

[[Nodule]] formation may also occur (nodules have a predilection for the posterior fossa). Diffuse [[meningitis]] or [[meningoencephalitis]] may occur and may be most pronounced at the base of the brain (basal meningitis) and in the subependymal region of the [[third ventricle]] (including the [[hypothalamus]]).

see [[Posterior fossa arachnoiditis]]

see [[Spinal arachnoiditis]].

Spinal involvement may include arachnoiditis, and lesions that may be intramedullary, extramedullary intradural and extramedullary extradural.

====Case description====
A 30-year-old male with Chiari malformation type I was treated by performing posterior fossa bone decompression, dura opening and closure with a suturable bovine pericardium dural graft. Postoperative period was uneventful until the fifth day in which the patient suffered intense headache and progressive loose of consciousness caused by an acute posterior fossa epidural hematoma. It was quickly removed with complete clinical recovering. One year later, the patient experienced progressive worsened of his symptoms. Upper spinal cord tethering was diagnosed and a new surgery for debridement was required.
CONCLUSIONS:
The epidural hematoma compressing the dural graft against the neural structures contributes to the upper spinal cord tethering and represents a nondescribed cause of postoperative fibrosis, adhesion formation, and subsequent recurrent hindbrain compression
((López-González A, Plaza E, Márquez-Rivas FJ. Postoperative epidural hematoma
contributes to delayed upper cord tethering after decompression of Chiari
malformation type I. Surg Neurol Int. 2014 Aug 21;5(Suppl 4):S278-81. doi:
10.4103/2152-7806.139384. eCollection 2014. PubMed PMID: 25225620; PubMed Central
PMCID: PMC4163907.
)).