Extensive spinal adhesive arachnoiditis after extradural spinal infection - spinal dura mater is no barrier to inflammation

BACKGROUND: Spinal adhesive arachnoiditis (SAA) is an inflammatory process of the meninges. Cystic changes and cicatrization may lead to neurologic deficits and immobilization. Therapy is difficult and often unsatisfactory. We describe 8 cases of extensive SAA after extradural spinal infection.

METHODS: A total of 238 patients with epidural abscess or osteomyelitis were treated at our institution between 2011 and 2018. We identified 8 patients who developed extensive SAA on follow-up. Different forms of the disease, radiologic changes, and potential treatment options are described.

RESULTS: Eight patients developed extensive SAA after either spontaneous epidural infection in 4 cases (50%) or after surgery or steroid injection (50%). Initial treatment for epidural infection was surgery without dural injury in 87.5%. One patient was treated conservatively. SAA was diagnosed 1 month to 8 years after the initial infection, not only in the index region but throughout the whole spine, with varying clinical symptoms. Treatment options such as corticosteroids (n = 4), thecaloscopy (n = 1), syringe-subarachnoid shunting (n = 1), and focal or multilevel arachnolysis (n = 5) were applied. In 2 patients (25%), a rare complication of internal malabsorptive hydrocephalus had to be treated. Patients showed diverse outcomes at last follow-up (mean, 37 months).

CONCLUSIONS: The prognosis for extensive SAA is poor. Surgical interventions may improve radiologic findings and clinical presentation at least temporarily. Even extradural infection can lead to severe SAA. Early surgery with local reduction of the epidural infection might reduce the risk of inflammation passing the dural sac and causing SAA.