Large demyelinating lesions: a neurosurgical perspective.

Area of Science:

• Neurology
• Neuro-oncology
• Pathology

Background:

• Large demyelinating lesions (LDLs) can present with symptoms mimicking brain tumors, including seizures and mass effect.
• Radiological features of LDLs are often ambiguous, complicating preoperative diagnosis.
• Increased intracranial pressure (ICP) necessitates timely intervention, but aggressive surgical resection of nervous tissue may lead to avoidable deficits.

Purpose of the Study:

• To describe the clinical and radiological characteristics of patients initially diagnosed with brain tumors but found to have large demyelinating lesions.
• To highlight the diagnostic challenges and optimal management strategies for LDLs presenting as tumors.

Main Methods:

• Retrospective case series of eight patients with focal neurological deficits and/or raised ICP initially suspected as tumors.
• Analysis of clinical presentation, radiological findings, and patient outcomes.
• Review of surgical interventions, including biopsy and decompressive surgery.

Main Results:

• All eight patients presented with focal deficits; five had raised ICP, and three experienced seizures.
• Radiological findings included irregular enhancement and concentric rings; four lesions involved the cortex.
• Surgical intervention improved sensorium in all patients, but focal deficits persisted; mortality occurred in three patients.

Conclusions:

• A high index of suspicion for demyelination is essential when encountering unexplained clinical features and atypical radiological findings suggestive of a tumor.
• Dissociation between contrast enhancement and mass effect on imaging warrants consideration of non-neoplastic lesions.
• For patients with minimal mass effect, biopsy is preferred; for those with significant mass effect, decompressive craniectomy and biopsy are recommended over complete resection, especially in eloquent areas.