Objective:

To characterize the clinicoradiological features of patients presenting with diffuse cauda equina root enlargement and to evaluate the diagnostic role of surgical biopsy in cases with uncertain etiology.

Approach:

• Study Design: Retrospective review of 12 patients with symptoms of cauda equina and diffuse nerve root enlargement on MRI from 2019 to 2024.
• Diagnostic Evaluation: Standardized diagnostic workup including MRI, CSF analysis, NCS/EMG, and serological testing; surgical biopsy performed in selected cases.
• Treatment and Follow-up: Treatment strategies based on diagnosis, including chemotherapy and immunotherapy; clinical follow-up conducted at 1, 3, and 6 months.

Key Findings:

• All patients exhibited diffuse enlargement of cauda equina nerve roots on MRI, with underlying etiologies including malignant lymphoma and immune-mediated neuropathies.
• Surgical biopsy provided important pathological information in cases with diagnostic uncertainty.
• Patients with lymphoma generally demonstrated favorable responses to systemic chemotherapy, while those with immune-mediated disorders improved following immunotherapy.

Interpretation:

Diffuse cauda equina nerve root enlargement is associated with heterogeneous etiologies, necessitating careful diagnostic evaluation.

Limitations:

• Small sample size limits generalizability.
• Retrospective nature may affect the consistency of data collection and outcomes.

Conclusion:

Surgical biopsy may be beneficial in selected cases when noninvasive investigations are inconclusive.