[Etiologies of unilateral block of epidural anesthesia: a case report]

We would like to present a patient, who was a 60 years old man, 160 cm tall, weighing 55 kg, which received debridement for his pressure sores under epidural anesthesia. While inserting the Touhy needle, there was obvious loss of resistance at the level of 9 cm below the skin. When the test dose was injected, the compliance was good. Later, the anesthesia behaved as unilateral block. After the operation, the computerized tomography revealed the epidural catheter was between the facia of right psoas major muscle. Form this case, there were some lesions: (1) The distance from the skin to the lumbar dura mater is seldom longer than 7 cm. (2) The obvious loss-of-resistance and good compliance of test dose are not the guarantee of epidural anesthesia. (3) The psoas block may be another cause of unilateral block of lumbar epidural anesthesia.