A 78‐year‐old man with a medical history of atrial fibrillation presented with complaints of 5 days of severe generalized weakness and difficulty walking. He also reported difficulty in getting up from a chair and difficulty while lifting his arm. On further questioning, he also reported taking an influenza vaccine shot a few days prior to his weakness. He reported s history of similar illness with respiratory issues requiring tracheostomy after a simple upper respiratory infection when he was 10 years old. Physical exam showed significant proximal as well as distal muscle weakness in the bilateral upper and lower extremities. Sensations were preserved, and reflexes were absent. His laboratory workup including complete blood count, electrolytes, TSH, CPK, and aldolase levels were normal. MRI head was unremarkable. An electromyogram with nerve conduction study showed evidence of chronic inflammatory demyelinating polyneuropathy (CIDP). This episode was probably from activation of chronic inflammatory demyelinating polyneuropathy triggered by influenza vaccination. The episode during childhood was presumably an episode of Gullian–Barré syndrome that developed into CIDP. He was promptly started on corticosteroids. He showed gradual improvement in weakness. He was subsequently sent to a physical rehabilitation center. The patient was advised not to repeat influenza vaccination in future.
Guillian–Barré syndrome, or GBS (acute inflammatory demyelinating polyneuropathy), and its chronic variant chronic inflammatory demyelinating polyneuropathy are rare disorders in general. There is evidence for causal association between oral polio vaccine and tetanus toxoid–containing vaccines and GBS/CIDP. Vaccines may also cause relapse of CIDP. Studies have shown only small or no risk of these disorders from influenza vaccine. Chronic inflammatory demyelinating polyneuropathy (CIDP) is an uncommon, immunologically triggered demyelinating disorder of peripheral nerves. The classic form is usually symmetric with more motor than sensory involvement. Both proximal as well as distal muscles may be involved. Most patients have some sensory impairment, and reflexes are absent. About 10%–20% of patients can have cranial nerve and bulbar involvement. It can have relapses with triggers. The mainstay of treatment is glucocorticoids. Intravenous immunoglobulins and plasmapheresis are preferred for severe and fulminant cases. About two‐thirds of cases respond well to initial treatment and have fairly good prognosis, but about 10%–15% cases are resistant to all treatments and have significant morbidity.
Currently, we do not have any definitive guidelines regarding provision of influenza vaccination to someone with a history of AIDP or relapse of CIDP with vaccination. Symptoms of weakness following vaccination should certainly prompt workup for demyelinating polyneuropathies, as suggested by our case.