Background and Aims Complex regional pain syndrome (CRPS) is a rare condition with not fully understood pathophysiology. Most cases are triggered by trauma or nerve lesion and are characterized by abnormal sensory, motor, and/or trophic findings. We present a case of CRPS following post-herpetic neuralgia, aiming to spread awareness about this poorly understood and underdiagnosed condition.

Methods A 76-year-old male with known history of hypertension and dyslipidemia was referred to the pain clinic due to uncontrolled pain in his left hand. Three months earlier, he was diagnosed with herpes zoster infection with post-herpetic neuralgia corresponding to the C6-C7 dermatome.

He complained of neuropathic pain with mechanic allodynia and hyperalgesia of the left hand, mainly in D1-D2 fingers, along with a decreased range of motion, temperature asymmetry, hypersensitivity, and diffuse edema, with significant limitation on daily activities.

Scaphotrapezoid osteoarthrosis and D1-3 edema were shown in radiography and ultrasound, respectively. Blood evaluation was unremarkable. The patient was diagnosed with CRPS by fulfilling all IASP Clinical Budapest Criteria.

Results He started multimodal therapy with gabapentin 300 mg, progressively titrated to 300 mg t.i.d., amitriptyline, and physiotherapy. Two months later, he reported significant functional improvement with decreasing edema and mild pain only.

Conclusions Varicella-zoster virus (VZV) is a known precipitating factor in CRPS. However, it is still unknown whether the disease occurs as a continuum of post-herpetic neuralgia or as a consequence of VZV neurotropism. Pharmacotherapy with gabapentinoids and tricyclic antidepressants have an important role in symptom control, but an early diagnosis and prompt physical rehabilitation are the cornerstones for successful outcomes.