Case:
We present the case of a 45 year old right-handed lady who developed chronic daily headache (CDH) with migraine features in 2018. She had migraine headaches in her teens, often associated with her menstrual cycle. The headaches progressively increased in frequency and severity in her 30s. In January 2018, after a viral infection, she developed unremitting headache with associated migraine symptoms and chronic daily headache (CDH). The pain is usually holocranial. She also has bilateral facial pain. There is associated phonophobia, worsening with physical activity and severe fatigue. The patient denied photophobia, nausea, vomiting and cranial autonomic symptoms. Poor sleep and physical activity worsen the headaches. The clinical examination was normal, including fundoscopy. Her routine blood tests including full blood count, biochemical profile, renal, liver, thyroid function, vitamin B12 and folate were within the normal limits. MRI brain and MR venogram (MRV) of the intracranial vessels were unremarkable. The patient has a previous history of varicose vein surgery and panic attacks. Her other medication consists of duloxetine 30mg daily, paracetamol PRN and naproxen PRN.
A diagnosis of chronic daily headache (CDH) with migraine features was made in 2018, and she was started on prophylactic medication. She had failed four migraine prophylactic drugs due to side effects or lack of efficacy: propranolol (minimal benefit), amitriptyline (weight gain), topiramate (significant cognitive impairment) and venlafaxine (worsening of headaches). Therefore, as per national and international guidelines, she was started on erenumab 70mg, monthly subcutaneous injection. The patient reported 40% improvement in headache severity and overall migraine symptoms, but with no crystal clear days.
Two weeks after the second injection of erenumab, she developed intermittent blue discoloration of both hands which worsened over a period of 7-8 months on Erenumab treatment (see Figure 1). There was no associated pain or sensory disturbance. The symptoms were worse in cold weather and improved in the summer time. Hand movements also improved the symptoms. The patient had never experienced such symptoms prior to erenumab administration. A diagnosis of RP secondary to erenumab was made. The patient initially declined discontinuation of erenumab, as she feared worsening of headaches and associated symptoms. However, she discontinued treatment after eight months due to the side effect of RP, both voluntarily and on medical advice.