Arachnoidales Web- eine effektiv behandelbare Ursache für Rückenmarkskompression und Syringomyelie- eine retrospektive monozentrische Erhebung

A very rare but potentially still underdiagnosed cause of spinal cord compression and syringomyelia has been identified as dorsal arachnoid web (AW), which is indicated on MRI by a dorsal indentation of the spinal cord (´scalpel-sign´), and sometimes associated with syringomyelia resulting from alterations of CSF flow-dynamics. We evaluated patients with the scalpel-sign regarding demographics, clinical presentation and imaging findings, and compared surgically and non-surgically treated patients´ outcome.

A retrospective chart study was conducted on patients with scalpel-sign on MRI, which were treated at a neurosurgical spine-center between 2016 and 2023. Treatment outcome was assessed using the thoracic Japanese Orthopedics Association (tJOA) score.

16 patients (mean age 56 ± 11 yrs, 8 males) were identified. Predeliction site of AW was the thoracic spine (T4-T6), with associated spinal cord lesions found in 56% of patients, mostly cranial (T2-T4) to the dorsal myelon indentation. Clinical manifestation comprised sensory deficits (69%), weakness and/or hyperreflexia of the legs (69%), ataxia (56%), back pain (56%), neuropathic pain (50%) and bladder dysfunction (6%). Median latency between symptom onset and diagnosing AW was 12 months. 63% of patients underwent surgery with mono- or bisegmental hemilaminectomy, durotomy, web removal with adhesiolysis and duroplasty. Median follow-up was 31.5 months. Symptoms worsened postoperatively in 1 patient, but improved (tJOA mean pre-/postoperatively: 8 ± 1.6/ 9 ± 1.8) in the majority of cases (70%), while conservatively treated patients did not improve: tJOA t0/t1: 9.5 ± 1.2/ 9.0 ± 1.9). Follow-up MRI showed regression of syringomyelia in surgically treated patients.

Surgical intervention appeared beneficial in the majority of patients, even in those with longstanding symptoms and spinal cord lesions, and may prevent further progression of the disease. Patients should be carefully screened for AW, as it identifies a rare but surgically effectively treatable cause of spinal cord compression and syringomyelia. Prospective longitudinal studies of both, surgically and non-surgically, treated AW patients should be conducted in order to gain a better understanding of the natural history of the disease, and to obtain further guidance in treatment decisions.