Case Report and Literature Review of Spinal Anesthesia-Related Peroneal Nerve Injury Complicated with Diabetic Foot Peripheral Neuropathy.

Perioperative peripheral nerve injury (PPNI) is rare but potentially disabling. In patients with diabetic peripheral neuropathy (DPN), the threshold for nerve injury is lowered due to microvascular compromise and impaired myelin repair. We report a 48-year-old male with type 2 diabetes and chronic foot ulcers who developed immediate left foot drop following low spinal anesthesia for debridement. Electrophysiology revealed conduction block and focal demyelination of the peroneal nerve at the fibular head; high-frequency ultrasound showed no structural abnormality, while lumbar magnetic resonance imaging (MRI) demonstrated a punctate T2 hyperintensity in the left L5 nerve root. Symmetrical sensory deficits supported underlying DPN. The findings suggested L5 nerve root irritation related to spinal anesthesia, resulting in secondary peroneal nerve dysfunction in the setting of diabetic peripheral neuropathy. Conservative management-including neuroprotection, ankle-foot orthosis, glycemic control, offloading, and early rehabilitation-led to significant recovery: dorsiflexion improved from 0/5 to 4/5 by 3 months, with electrophysiological evidence of remyelination. This case underscores the need for a stratified diagnostic approach (rule out central, then clarify peripheral) and highlights that functional nerve injury can occur without compressive findings on imaging. Early multimodal intervention enables favorable outcomes even in vulnerable diabetic patients.