In Reply:—

We would like to thank Dr. Aldrete for his remarks, which enlighten our clinical and magnetic resonance imaging (MRI) findings in a patient with transient neurologic symptoms after spinal injection of lidocaine.

As Dr. Aldrete commented, there is more to be learned about this phenomenon and about MRI findings at different stages not only after intrathecal, but also after epidural anesthesia.

Although epidural infection is a very rare complication, it has become an important clinical problem with the increased use of epidural catheters for prolonged analgesia. At present, MRI is the diagnostic procedure of choice. Although the characteristic appearance of epidural and spinal infection is well documented by MRI, it has not been compared with MRI findings in asymptomatic patients after epidural or spinal injections (with or without catheter). This lack of knowledge may cause a problem in diagnosis when evaluating MRI scans of patients with suspected epidural or spinal infections.

We are therefore planning a controlled prospective study of serial MRI after spinal and epidural injections.