Co-occurrence of En Coup de Sabre, Parry-Romberg Syndrome, and Hemi Masticatory Spasm: A Case Report

Introduction: En coup de sabre (ECDS) and Parry-Romberg syndrome (PRS) are rare, localised scleroderma subtypes, often considered to be overlapping variants of morphea. Hemi masticatory spasm (HMS), a distinct rare neuromuscular disorder characterised by unilateral paroxysmal contraction of the jaw muscles, has rarely been reported in association with these conditions. Case Presentation: A 20-year-old man presented with a linear, cicatricial alopecic patch over the left parietal scalp, along with indurated and bound-down skin over the left cheek. This was followed by progressive depression and asymmetry of the left midface, accompanied by paroxysmal spasms during mastication and swallowing. Examination revealed cicatricial alopecia over the left parietal region and an atrophic plaque over the ipsilateral cheek. The left lower lip and tongue were atrophic, while the ipsilateral masseter muscle was visibly hypertrophied. Histopathological findings of the cheek lesion were consistent with morphea. A clinical diagnosis of co-existing ECDS, PRS, and HMS was made. Botulinum toxin type A was used to treat HMS, with marked reduction in symptoms and improvement in quality of life. Conclusion: This case highlights the rare but meaningful association between ECDS, PRS, and HMS, underscoring the importance of early recognition and multidisciplinary intervention. Botulinum toxin remains a valuable therapeutic option for managing symptomatic HMS in such contexts.