Introduction: Neurofibromatosis Type I (NF1) is an autosomal dominant disease with a spectrum of manifestations including dural ectasia which can vary from simple meningeal diverticula to marked widening of the spinal canal or even large meningoceles and irregular posterior vertebral scalloping (Figure 1). In their most severe form, they require surgical intervention. The histopathology and management of this entity is unclear. We report the histopathology, natural history, and management of dural ectasia in a series of NF1 patients.
Methods: A retrospective analysis of all NF1 patients diagnosed with radiographic findings associated with dural ectasias from 1998-2017 was conducted. Fifty-five patients were identified (mean age 33, 3:2 M:F). Of those, 10 patients (3 male, 7 female) warranted neurosurgical consultation due to significant symptoms. The mean age at diagnosis for this subgroup was 40.5 years (range: 6 - 73). Mean follow-up was 6.4 years (range: 1-16).
Results: Of the 10 patients, the most common presenting symptom was back pain with radiculopathy (80%). Symptomatic dural ectasia was most common in the thoracic spine (5 thoracic, 2 lumbar and 3 sacral), spanning an average of 4 levels. Three patients underwent surgical intervention due to enlarging mass effect. All interventions were temporarily successful; however, all subsequently suffered recurrence requiring CSF shunting devices with no recurrence of symptoms at 1.5, 2, and 6 years, respectively. Histopathology of one resected lesion revealed unexpected involvement of the dura by diffuse neurofibroma confirmed by S100 labeling.
Conclusions: We describe the nature and clinical course of several NF1-related dural ectasias. This study is the first to note the histopathological nature of one of these lesions that demonstrates dural infiltration by diffuse neurofibroma. Our clinical experience suggests that drainage and resection for symptomatic dural ectasia does not necessarily provide durable management, as our interventions all required CSF diversion after re-occurrence.
Patient Care: This study highlights the natural course of dural ectasia, the surgical consideration for recurrence and for the first time, the histopathology of these entities.
Learning Objectives: 1) NF1 associated dural ectasias may result in significant symptoms
2) For those that are symptomatic, surgical decompression alone was not sufficient to prevent reoccurrence.
3) Dural ectasias histopathological nature and possibly their tendency to re-occur may be a result of diffuse neurofibroma infiltration.