When taking biopsies to assess skin strength in Ehlers–Danlos syndrome type III (EDS–III), a Danish group noticed that the patients experienced much pain despite conventional local anaesthesia. When asked, all these patients reported previous experience of partial or complete failure of local anaesthesia in dental or obstetric procedures—for which reason some had been dismissed as hysterics. Pursuing this finding, Arendt-Nielsen compared the effects of local anaesthesia in 8 patients with EDS–III and 8 controls. Although the patients did gain analgesia from intradermal lidocaine the duration of effect was much shorter than in controls. EDS–III (now known as EDS–hypermobility type) is regarded by many authorities as identical to joint hypermobility syndrome (JHS). We wish to draw attention to the possibility of resistance to local anaesthesia in individuals with this common and under-diagnosed condition. Although the pathophysiology of this phenomenon remains unresolved, an important clue that a patient is at risk of local anaesthetic failure might be in front of our eyes.
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