Clinical Focus

  • Anesthesia
  • Pain Management
  • Radiculopathy
  • Spinal Pain
  • Neuralgia, Postherpetic
  • Abdominal Pain
  • Workers' Compensation
  • Cancer Pain

Academic Appointments

  • Clinical Associate Professor, Anesthesiology, Perioperative and Pain Medicine

Administrative Appointments

  • Clinic Chief, Pain Management Center (2010 - Present)

Professional Education

  • Internship:George Washington University (1994) DC
  • Board Certification: Pain Medicine, American Board of Anesthesiology (2000)
  • Fellowship:Stanford University School of Medicine (1998) CA
  • Residency:Stanford University School of Medicine (1997) CA
  • Residency:UC Davis Medical Center (1994) CA
  • Medical Education:Georgetown University Hospital (1993) DC
  • Board Certification: Anesthesia, American Board of Anesthesiology (1999)

Research & Scholarship

Current Research and Scholarly Interests

- Intrathecal / Intraspinal Analgesics
- Industry-supported clinical trials


2015-16 Courses


All Publications

  • Intrathecal Ziconotide for Complex Regional Pain Syndrome: Seven Case Reports PAIN PRACTICE Kapural, L., Lokey, K., Leong, M. S., Fiekowsky, S., Stanton-Hicks, M., Sapienza-Crawford, A. J., Webster, L. R. 2009; 9 (4): 296-303


    Ziconotide is a nonopioid analgesic currently indicated as monotherapy, but frequently used in combination with opioids, for the management of severe chronic pain in patients for whom intrathecal (IT) therapy is warranted and who are intolerant of, or whose pain is, refractory to other treatments. There is a paucity of information regarding ziconotide use in patients with complex regional pain syndrome (CRPS). Seven cases in which IT ziconotide was used in patients with CRPS were analyzed. All patients (4 male, 3 female; age range, 14 to 52 years) had experienced inadequate pain relief with multiple conventional and interventional treatments. Three patients received ziconotide monotherapy exclusively; 4 patients received ziconotide monotherapy initially, then combination IT therapy. The mean ziconotide dose was 5.2 mcg/d (range, 0.5 to 13 mcg/d) at initiation and 24.7 mcg/d (range, 0.06 to 146 mcg/d) at the last available assessment. The mean duration of ziconotide therapy was 3.1 years (range, 26 days to 8 years). At ziconotide initiation, the mean visual analog scale (VAS) score was 89.3 mm (range, 75 to 100 mm); VAS scores decreased by a mean of 47.5% (range, 5% to 100%) at last assessment. Of the 5 patients who experienced substantial improvement in pain, edema, skin abnormalities, and/or mobility with ziconotide therapy, 2 have discontinued ziconotide and are pain free. Another patient experienced marked reversal of both edema and advanced skin trophic changes. Adverse events included urinary retention, depression, anxiety, and hallucinations. Adverse events generally resolved spontaneously, with treatment, or with ziconotide discontinuation/dose reduction. Although further studies are required, ziconotide holds promise as an effective treatment for CRPS.

    View details for DOI 10.1111/j.1533-2500.2009.00289.x

    View details for Web of Science ID 000208107800008

    View details for PubMedID 19500276

  • A novel needle-free powder lidocaine delivery system for rapid local analgesia JOURNAL OF PEDIATRICS Zempsky, W. T., Robbins, B., Richards, P. T., Leong, M. S., Schechter, N. L. 2008; 152 (3): 405-411


    To determine the analgesic effect and tolerability of a novel needle-free powder lidocaine delivery system in children undergoing venipuncture.In this double-blind, placebo-controlled, single-center trial, 306 children age 3 to 18 years were randomized to receive a needle-free powder lidocaine delivery system or matching sham placebo at the back of the hand 2 to 3 minutes before venipuncture. Venipuncture pain was self-reported using the Wong-Baker FACES scale (in 3- to 12-year-olds) and a 100-mm visual analog scale (in 8- to 18-year-olds). Safety was assessed by adverse events, investigator skin site assessments, and children's self-report of the administration comfort of study treatments. Effect sizes were compared by 2-sample t test and Glass's Delta approach.Subjects receiving the needle-free powder lidocaine delivery system exhibited mean pain reductions (effect size) of 33% to 46% relative to sham placebo. Pain reductions were statistically significant for all ages combined and also for the youngest and oldest age strata. Self-reported administration comfort levels were similar in the active system and sham placebo groups. Incidences of adverse events and dermal reactions were low; the most common dermal reaction was mild erythema.The needle-free powder lidocaine delivery system was well tolerated and provided effective local analgesia when administered 2 to 3 minutes before venipuncture.

    View details for DOI 10.1016/j.jpeds.2007.07.018

    View details for Web of Science ID 000253599800023

    View details for PubMedID 18280850

  • Dose-finding, safety, and tolerability study of botulinum toxin type B for the treatment of hyperfunctional glabellar lines DERMATOLOGIC SURGERY Carruthers, A., Carruthers, J., Flynn, T. C., Leong, M. S. 2007; 33: S60-S68


    Previous open-label studies have demonstrated that botulinum toxin type B (BTX-B, Myobloc, Solstice Neurosciences) in doses of up to 3,000 U is safe and effective in the treatment of glabellar wrinkles.This double-blind, randomized, placebo-controlled, sequential-dose-escalation study evaluated the safety and tolerability of seven BTX-B doses ranging from 250 to 3,000 U in the treatment of subjects with hyperfunctional glabellar lines.Participants received a single intramuscular treatment of either BTX-B or placebo at five facial sites with a 12-week follow-up period. Primary efficacy outcome measure was the Investigator Global Scale score of subject's glabellar lines at rest and at full frown. Safety was evaluated primarily on the occurrence of adverse events (AEs).The investigator scores demonstrated a statistically significant increasing dose-response trend in the percentage of subjects with no lines or mild lines at rest from Weeks 1 to 12 (p=.0420) and at full frown from Weeks 1 to 8 (p<.0001). Fifty-one subjects (36.7%) experienced AEs; the most common AE was headache not otherwise specified, experienced by 19 subjects (13.7%).BTX-B at doses up to 3,000 U was safe and well tolerated in the treatment of hyperfunctional glabellar lines. Treatment with BTX-B reduced hyperfunctional glabellar lines in subjects, and the duration of action appeared to be related to the dose administered. Further studies using higher doses of BTX-B for treatment of glabellar wrinkles are planned.

    View details for DOI 10.1111/j.1524-4725.2006.32333.x

    View details for Web of Science ID 000253377900010

    View details for PubMedID 17241416

  • A randomized, double-blind, placebo-controlled study of intrathecal ziconotide in adults with severe chronic pain JOURNAL OF PAIN AND SYMPTOM MANAGEMENT Rauck, R. L., Wallace, M. S., Leong, M. S., MineHart, M., Webster, L. R., Charapata, S. G., Abraham, J. E., Buffington, D. E., Ellis, D., Kartzinel, R. 2006; 31 (5): 393-406


    Safety and efficacy data from a study of slow intrathecal (IT) ziconotide titration for the management of severe chronic pain are presented. Patients randomized to ziconotide (n = 112) or placebo (n = 108) started IT infusion at 0.1 microg/hour (2.4 microg/day), increasing gradually (0.05-0.1 microg/hour increments) over 3 weeks. The ziconotide mean dose at termination was 0.29 microg/hour (6.96 microg/day). Patients' baseline Visual Analogue Scale of Pain Intensity (VASPI) score was 80.7 (SD 15). Statistical significance was noted for VASPI mean percentage improvement, baseline to Week 3 (ziconotide [14.7%] vs. placebo [7.2%; P = 0.036]) and many of the secondary efficacy outcomes measures. Significant adverse events (AEs) reported in the ziconotide group were dizziness, confusion, ataxia, abnormal gait, and memory impairment. Discontinuation rates for AEs and serious AEs were comparable for both groups. Slow titration of ziconotide, a nonopioid analgesic, to a low maximum dose resulted in significant improvement in pain and was better tolerated than in two previous controlled trials that used a faster titration to a higher mean dose.

    View details for DOI 10.1016/j.jpainsymman.2005.10.003

    View details for Web of Science ID 000238207700010

    View details for PubMedID 16716870

  • Pump battery assessment: Cold, old, or dead! NEUROMODULATION Leong, M. S., Carpentier, B. W. 2001; 4 (3): 117-119


    Intraspinal drug delivery systems are becoming increasingly utilized for the management of patients with pain or spasticity. Numerous potential complications associated with the use of this technology have previously been described in the literature. We have had experience with a new complication of the internal alarm being triggered by the instillation of cold solution into the pump resevoir. This new finding could have implications for patients with respect to unnecessary reevaluations of the pump, or possible premature scheduling of pump replacement surgery.

    View details for Web of Science ID 000169693100005

    View details for PubMedID 22151656

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