A 70-year-old woman presented to the emergency department with acute progressive bilateral symmetric ascending flaccid tetraparesis and bladder dysfunction. Patient history included allergy to penicillin, hypertension, and degenerative osteoarthritis of the knee.

Seven weeks before admission, neurological manifestations started with tingling of the toes, progressive acute weakness of the distal lower extremities, and urinary retention. Three weeks prior to these symptoms, the patient received the first dose of the ChAdOx1 vaccine.

On admission, she was afebrile, and her vital signs were as follows: blood pressure, 132/85 mmHg; respiratory rate, 17 cycles/min; oxygen saturation, 99% on room air; heart rate, 96 bpm. Physical examination revealed a normal mental status and speech. Motor examination demonstrated muscular weakness with a Medical Research Council scale of 3/5 proximally in the lower limbs, and 4/5 proximally and distally in the upper extremities. The distal strength in the bilateral upper extremities was 5/5. The deep tendon reflexes were reduced with bilateral areflexia of the patellar, bicipital, and tricipital reflexes. Sensory deficits were not observed. No signs of an upper motor neuron disorder or meningeal irritation were observed. Magnetic resonance imaging of the entire neuroaxis, with and without contrast, was unremarkable for any acute or chronic pathology that may correlate with her symptoms.

Laboratory investigations revealed a hemoglobin of 13.9 g/dl with a hematocrit of 40%, leukocyte count of 6910/mm³, erythrocyte sedimentation rate at the first hour was 25 mm, and electrolyte, renal, and hepatic functions were within normal limits. Tests for HIV, syphilis, HVB, and HVC were also normal. Covid-19 PCR were negative. Cerebrospinal fluid examination revealed clear fluid, normal opening pressure, glucose 0.78 g/L (glycemia 1.71 g/L), and albumin-cytologic dissociation with proteins of 1.25 g/l and white blood cells < 2/mm³. Electrophysiological studies of motor nerve conduction have shown delayed distal latencies and the absence of F waves. The sensory nerve conduction was within the normal range (Table 1). Based on physical examination, cerebrospinal fluid findings, and electrophysiological study, a diagnosis of acute demyelinating polyradiculoneuropathy consistent with Guillain?Barre syndrome was made.

Intravenous immunoglobulin was administered at a dose of 0.4 g/kg for 5 days with physical therapy sessions, and no complications were observed during or after the treatment. The National Center of Pharmacovigilance was notified of this complication associated with the ChAdOx1 vaccine. After 6 months of follow-up, satisfactory evolution was noticed, without motor or sensory sequelae. Given the good outcome, it was not necessary to perform an EMG control.

A 68-year-old woman with a history of hypertension and no reports of any travel or infectious episodes presented to the emergency department with symptoms of descending, symmetrical, and synchronous tetraplegia, preceded 4 days before by diffuse headaches with impairment of multiple cranial nerves and bladder dysfunction.

One week before admission, the initial neurological manifestations were diffuse headaches, diplopia, and facial paralysis. The clinical picture progressively deteriorated over two days with severe dysphonia and dysphagia to solids and liquids. The evolution was marked thereafter by paresthesias in the extremities, with descending, symmetrical weakness rapidly evolving over four days beginning in her arms, then lower limbs, and urinary retention. Three weeks before these manifestations occurred, the patient benefited from the first dose of the ChAdOx1 vaccine.

On admission, the patient was asthenic, and initial vital signs were as follows: heart rate, 98 beats/min; respiratory rate, 20 breaths/min; blood pressure, 138/84 mmHg; temperature, 37.4˚C, saturation 96% on room air.

Examination revealed several cranial neuropathies including facial diplegia, bilateral oculomotor paralysis, bilateral soft palate paralysis and abolition of the pharyngeal reflex. Motor examination revealed hypotonia in all four limbs, with weakness estimated to be 2/5 in the proximal and distal muscles. The patient exhibited generalized areflexia.

There were no sensory impairments or upper motor neuron involvements. The biological assessment revealed no abnormalities. Brain MRI was normal. Coronavirus Cov-2 PCR results were negative. Analysis of cerebrospinal fluid (CSF) showed albumin-cytologic dissociation (protein of 1.22 g/l and WBC of 3). ENMG performed on the same day of hospitalization showed acute inflammatory axonal and demyelinating polyradiculoneuropathy (Table 1).

Immunoglobulin was started on the fourth day of hospitalization (0.4 g/kg for 5 days) without any significant complications. Clinical improvement was observed on the third day of treatment. This case was also reported to the National Pharmacovigilance Center. After 6 months of follow-up, the patient regained strength in both upper and lower limbs, so as cranial nerves functions. Given the good outcome, it was not necessary to perform an EMG control.