Disclosures: Harnek S. Bajaj, MD: No financial relationships or conflicts of interest

Case Description: The patient had surgery about 7 months prior to presentation to the pain clinic. 2 weeks postoperatively, the patient complained of exquisite pain, paresthesias, hypersensitivity, and swelling in his right forearm extending into the hands. Examination revealed decreased range of motion and limited strength in the finger flexors and wrist, as well as trophic changes at the fifth digit, and hyperesthesia. The diagnosis of complex regional pain syndrome (CRPS) was made, and the patient was initially prescribed occupational therapy to work on his range of motion, in addition to duloxetine. After minimal improvement, memantine (off-label use), ten milligrams, twice a day, was prescribed.

Setting: Outpatient PM&R Pain Clinic

Patient: 78 year old male with history of diabetes mellitus and coronary artery disease presented with chronic right upper extremity pain following surgery for a right rotator cuff repair Assessment/

Results: A stellate ganglion nerve block was contraindicated due to allergy to contrast dye. An ulnar neuropathy was suspected but ruled out via ultrasound. At the patient’s three month follow up after initiation of memantine, he revealed marked pain relief and improved range of motion for the first time.

Discussion: Memantine is a synthetic adamantine derivative and N-methyl-D-asparate receptor (NMDAR) antagonist that is used most commonly for treatment of Alzheimer’s disease. There is a growing body of literature which suggests that the NMDAR within the dorsal horn holds a key role with regards to inflammation and nerve injury-induced central sensitization. For this reason, memantine, may be useful in the treatment of neuropathic pain conditions such as CRPS.

Conclusion: Here, we present a case of CRPS which was developed after rotator cuff surgery, and was successfully treated with memantine in combination with standard management. Future randomized controlled trials should be conducted to further elucidate the efficacy of memantine for CRPS.

Level of Evidence: Level V

« Back to AAPM&R Annual Assembly 2020

PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/memantine-as-a-treatment-modality-in-a-patient-with-complex-regional-pain-syndrome-after-rotator-cuff-surgery-a-case-report/