E89 www.painphysicianjournal.com Brief Communication www.painphysicianjournal.com Onset of Spontaneous Lower Extremity Pain After Lumbar Sympathetic Block L umbar sympathetic nerve blocks (LSBs) can be performed to determine whether or not a patient’s pain is sympathetically mediated. They can be used as prognostic injections to determine the response to future more permanent sympathectomy or as therapeutic interventions on their own. Common presentations of sympathetically mediated pain include vascular insufficiency and peripheral nerve injuries suffered in trauma or limb amputation. Such injuries play a prominent role in complex regional pain syndrome (CRPS). The Budapest Criteria detailed in the Table 1 describe the conditions under which a diagnosis of CRPS can be made (1). CRPS is characterized by severe pain, pseudomotor, and vasomotor symptoms affecting a specific area of the body that is sometimes associated with injury or nerve damage. Pain originates from multiple sources including neurogenic inflammation, vasomotor dysfunction, and changes in central pain processing. It is the result of the body’s abnormal response to tissue injury with varying clinical presentations including hyperalgesia, allodynia, swelling and skin discoloration. LSBs are one of the early interventions used to treat CRPS because they are minimally invasive, have a long safety record, and can help determine what component of the pain is sympathetically mediated. Case Report The patient discussed herein consented to the use of this case for educational purposes. A 50-year-old woman presented with chronic right lower extremity (RLE) pain. Her medical history included morbid obesity, status-post bariatric surgery, diabetes, hypertension, anxiety, transient ischemic attack, and bilateral carotid artery stenosis. She complained of severe right lower extremity pain as if her “leg was on fire.” The pain was perceived to originate from the ankle and radiate towards the knee. Exam demonstrated significant tenderness to palpation diffusely in the RLE in the same distribution. She also endorsed generalized weakness in the RLE, and the right calf was visibly atrophied versus the left. Range of motion exam resulted in severe pain in the knee and ankle. The patient showed decreased ability to discern light touch from pinprick sensation from knee to ankle on the RLE. The RLE was about 1 degree Celsius warmer than the left from toes to knees. Recent electromyography and nerve con- duction studies (EMG) were negative for large fiber neuropathy in the affected limb. Lower extremity magnetic resonance imaging (MRI) and vascular consultation were also negative and she failed medication therapy with gabapentin 300 mg 3 times per day. A differential diagnosis of peripheral neuropathy versus CRPS was given and the patient was scheduled for a right lumbar sympathetic block. From: University of Texas Health Science Center at San Antonio, San Antonio, TX Address Correspondence: Samuel Stevens, MD Department of Anesthesiology University of Texas Health Science Center at San Antonio Mail Code 7838 7703 Floyd Curl Drive San Antonio, Texas 78229-3900 E-mail: stevenssh@uthscsa.edu v Disclaimer: There was no external funding in the preparation of this manuscript. Conflict of interest: Each author certifies that he or she, or a member of his or her immediate family, has no commercial association (i.e., consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted manuscript. Accepted for publication: 11-17-2014 Free full manuscript: www.painphysicianjournal.com Ameet Nagpal, MD, Maxim Eckmann, MD, Scott Small, DO, and Samuel Stevens, MD Pain Physician 2015; 18:E89-E91 • ISSN 2150-1149