HY Kim, et al / Psoas Compartment Block in a Laterally Herniated Disc 119 muscles had not been suspected, diagnosis would have been delayed under the false judgment that there were no disc problems. There are not many studies regarding the relationship between lateral disc herniation and the psoas muscle. However, there is a study that analyzes the con- nection between the sciatica and the reduced sectional area of the psoas muscle resulting from lateral disc her- niation [12]. In addition, a case study reporting similar symptoms to meralgia paresthetica that results from lat- eral disc herniation is also available [13]. Since the psoas muscle is adjacent, through fibrous attachments, to all discs in the lumbar excluding the discs between L5 and S1 [14], lesions in the lumbar disc can affect the fascia dis- ease of the psoas muscle [2]. This knowledge should also be included in the differential diagnosis. Treatment regarding myofasciopathy, caused by the compression of the psoas muscle, is based on conservative treatment, but there is no proven definite treatment as of yet [14]. The authors thought of the mechanism for pain relief and gait abnormality when a psoas compartment blockade was performed using steroids. The psoas com- partment is the space located between the psoas muscle and quadrates lumborum, and is surrounded by the psoas muscle and its fascia in the front, the lumbar, and the transverse process of the lumbar, ligament, muscle, and quadrates lumborum in the back [15]. Within this compart- ment, the lumbar plexus, the ventral ramus of the sacral plexus, iliohypogastric nerve, ilioinguinal nerve, genito- femoral nerve, lateral femoral cutaneous nerve, femoral nerve, obturator nerve, and parts of the sciatic nerve pass through [3]. The psoas compartment block is generally performed on the L3 or L4 disc and serves to block the lateral femoral cutaneous nerve, femoral nerve, and the obturator nerve, so the block is also known as the posteri- or lumbar plexus block. The iliohypogastric, ilioguinal, and genitofemoral nerve can be further blocked if medication is expanded toward the cephalad within the fascia [16]. As in this case, where the psoas compartment block was per- formed on L3, the steroid and local anesthetic is spread to the psoas muscle fascia and nerve within the psoas compartment, which relieves pain in the psoas muscle and hip joint, and results in the improvement of gait abnor- mality. The amount of steroid used in the psoas compart- ment block is not determined in general, but 40-80 mg of triamcinolone diacetonide is used for each procedure when performing the epidural block [17]. However, in the www.epain.org case of the psoas compartment block, the fascia is located adjacently so muscle atrophy can occur from the steroid, and since the patient in this case had diabetes as an un- derlying disease, only 5 mg of triamcinolone diacetonide was used in the initial procedure. There was also the pur- pose of determining the effects of the blockade. Therefore in further additional procedures, increasing the amount of steroid can be considered. It was found that using local anesthesia, coupled together with steroids, is more effec- tive and also possesses long-term pain relief. These ef- fects are thought to be from the steroid suppressing the hypothalamus, pituitary gland, and the adrenal gland [6]. The patient in our case had a history of rectal cancer and had diabetes as an underlying disease, so an abscess in the psoas muscle or metastasis was suspected. However, the suspicion proved to be incorrect since the symptoms had gradually occurred for two years and there were no signs of infection. The MRI results showed compression of the psoas muscle by a laterally herniated disc, so pain was relieved and gait abnormality improved through the psoas compartment blockade. In these kinds of patients, detailed history taking, physical examination, and imaging should be performed for accurate diagnosis and proper treatment, with the psoas compartment blockade now being able to be considered as another treatment method. REFERENCES 1. Bogduk N, Pearcy M, Hadfield G. Anatomy and biome- chanics of psoas major. Clin Biomech (Bristol, Avon) 1992; 7: 109-19. 2. Travell JG, Simons DG. Myofascial pain and dysfunction: the trigger point manual. Baltimore, Lippincott Williams & Wilkins. 1983, pp 89-109. 3. Brown DL. Psoas compartment block. Atlas of regional anesthesia. 3rd ed. Philadelphia, Elsevier/Saunders. 2006, pp 95-6. 4. Chayen D, Nathan H, Chayen M. The psoas compartment block. Anesthesiology 1976; 45: 95-9. 5. Chelly JE, Casati A, Al-Samsam T, Coupe K, Criswell A, Tucker J. Continuous lumbar plexus block for acute post- operative pain management after open reduction and internal fixation of acetabular fractures. J Orthop Trauma 2003; 17: 362-7. 6. Lee WJ, Sung NS, Kim C. Effect of psoas compartment block in low extremity pain from stomach cancer: a case report. J Korean Pain Soc 1992; 5: 113-6. 7. Lansdown AJ, Downing A, Roberts AW, Martin D. Psoas