Subdural block: a possible cause of transient aphasia following spinal anaesthesia

Central neuraxial blockade is a commonly performed anaesthetic technique for lower limb orthopaedic surgeries. Although it is considered a safe and reliable technique, occasionally an unexpectedly high or low level of block can be achieved due to accidental injection of local anaesthetic in a meningeal plane other than that desired. Here we report a young male who complained of aphasia and difficulty in breathing immediately after spinal anaesthesia. He had a high sensory block extending to C3 dermatome. His haemodynamics remained stable throughout the surgery. Speech returned to normal in 15 minutes. Subdural block was speculated as a cause for this unusual presentation.