Trigeminal neuropathic pain in a patient with progressive facial hemiatrophy (Parry-Romberg syndrome)

Background: We reviewed the literature on published cases of progressive facial hemiatrophy (Parry-Romberg syndrome) to identify possible pathophysiological mechanisms of the syndrome. Objective: To describe the somatosensory phenotype of a previously unreported patient with progressive facial hemiatrophy and facial pain. Design: Case report and 4-month follow-up period. Setting: University-based tertiary referral headache center. Patient: A 37-year-old woman with progressive facial hemiatrophy and strictly left-sided facial pain over 12 years. Intervention: Greater occipital nerve blockade with lidocaine, 2% (2 mL), and methylprednisolone sodium phosphate (80 mg). Main Outcome Measures: Trigeminal sensory phenotype on quantitative sensory testing using thermal threshold and Von Frey hairs. The case report includes patient photographs, neuroimaging, and neurophysiological findings. Results: On the left side, there was continuous pain in V₁ and V₂ and intermittent sharp shooting pains in V₃. The sensory examination showed areas on the left side with pinprick hyperalgesia, cold and heat hyperalgesia, and dynamic mechanical allodynia. The pain in V₁ and V₃ and the allodynia dramatically improved after greater occipital nerve blockade. In the cases reported in the literature, a constant component of the pain was always part of the phenotype, and positive or negative trigeminal sensory signs were frequently described. Conclusions: The phenotype of our patient suggests neuropathic pain involving all 3 branches of the trigeminal nerve, and the patient fulfills newly defined stricter criteria for neuropathic pain. Similar to our case, phenotypes of the other published cases seem to agree with trigeminal neuropathic pain rather than trigeminal neuralgia specifically.