Magnetic resonance imaging-based morphobehavioral classification of intradural spinal arachnoid cysts: Correlation with cord integrity, surgical outcomes, and recurrence.

BACKGROUND

Intradural spinal arachnoid cysts (SACs) are rare benign lesions that may cause progressive myelopathy, radiculopathy, or sphincter dysfunction. Existing classifications are largely descriptive and lack prognostic utility.

OBJECTIVE

To evaluate the clinical, radiological, and surgical characteristics of intradural SACs and propose an magnetic resonance imaging (MRI)-based morphobehavioral classification with prognostic relevance.

MATERIALS AND

METHODS

We retrospectively reviewed 25 patients who underwent surgery for intradural SACs between 2005 and 2025. Demographic, clinical, imaging, and operative details were analyzed. Based on MRI features and cord morphology, cysts were categorized into four types: web-like (Type I), encapsulated (Type II), multiloculated (Type III), and adhesive (Type IV). Outcomes were assessed using the Nurick grading system; recurrence was defined radiologically.

RESULTS

The mean age was 33.9 ± 21.1 years, with male predominance (76%). Myelopathy was the most common presentation (88%), and 80% were Nurick grades 3-5 at diagnosis. Most cysts were thoracic (64%) and dorsal/dorsolateral (52%). Cord atrophy, with or without syrinx, was observed in 52%. Surgical management included marsupialization (56%), total excision (36%), and partial excision (8%), with dorsal cysts more often excised (P = 0.018). At a mean follow-up of 33.9 ± 32.4 months, 55% improved, 30% remained stable, and 15% deteriorated. Cord integrity correlated significantly with cyst type (P = 0.012); Type I-II cysts showed better recovery but accounted for all recurrences (15%).

CONCLUSION

MRI morphology and cord status correlate with outcomes. Discrete cyst phenotypes demonstrate better recovery but potential delayed recurrence, whereas adhesive cysts are associated with severe cord compromise and limited improvement.