Guillain-Barre syndrome; This literature-non-study case was reported in a literature article and describes the occurrence of GUILLAIN-BARRE SYNDROME (Guillain-Barre syndrome) in a 7-decade-old male patient who received mRNA-1273 (Spikevax) for COVID-19 vaccination.       The patient's past medical history included Ruptured cerebral aneurysm (Ruptured left middle cerebral artery aneurysm), Weakness of limbs and Gait instability. Concurrent medical conditions included Blind right eye.    On an unknown date, the patient received dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date, the patient experienced GUILLAIN-BARRE SYNDROME (Guillain-Barre syndrome) (seriousness criterion medically significant). The patient was treated with IMMUNOGLOBULINS NOS (IMMUNE GLOBULIN) (intravenous) for Adverse event, at an unspecified dose and frequency. At the time of the report, GUILLAIN-BARRE SYNDROME (Guillain-Barre syndrome) had resolved. Related    DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Angiogram: albumino-cytological dissociation (abnormal) no acute intracranial bleeding and no vascular abnormalities. With the findings of diffuse hyporeflexia and cerebrospinal fluid showing albumino-cytological dissociation, Guillain-Barre syndrome was high on the differentials. On an unknown date, Computerised tomogram head: albumino-cytological dissociation (abnormal) no acute intracranial bleeding and no vascular abnormalities. With the findings of diffuse hyporeflexia and cerebrospinal fluid showing albumino-cytological dissociation, Guillain-Barre syndrome was high on the differentials. On an unknown date, Computerised tomogram neck: albumino-cytological dissociation (abnormal) no acute intracranial bleeding and no vascular abnormalities. With the findings of diffuse hyporeflexia and cerebrospinal fluid showing albumino-cytological dissociation, Guillain-Barre syndrome was high on the differentials. On an unknown date, Electromyogram: evidence of demyelination (abnormal) Evidence of demyelination.     The action taken with mRNA-1273 (Spikevax) (Unknown) was unknown.   For mRNA-1273 (Spikevax) (Unknown), the reporter considered GUILLAIN-BARRE SYNDROME (Guillain-Barre syndrome) to be related.    No concomitant medications were reported.  The patient was presented with loss of balance, weakness of his legs and fatigue for 3 days. The patient was discharged to rehab with complete symptom resolution.  Company comment: This literature-non-study case concerns a 7-decade-old male patient, with medical history of ruptured left middle cerebral artery aneurysm, with residual right eye blindness and right leg weakness with gait instability, who experienced the unexpected serious (medically significant) ADR of GUILLAIN-BARRE SYNDROME. Patient received a dose of mRNA-1273 vaccine 3 days before symptom onset. Patient presented with loss of balance, weakness of his legs and fatigue for 3days. Approximately 4 weeks later patient was presented. CT of head and CT angiogram of the head and neck were performed and demonstrated no acute intracranial bleeding and no vascular abnormalities. With the findings of diffuse hyporeflexia and cerebrospinalfluid showing albumino-cytologicaldissociation, Guillain-Barre syndrome was high on the differentials. Electromyogram showed evidence of demyelination. He was treated with intravenous immune globulin (IVIG) and was discharged to rehab with complete symptom resolution. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.; Sender's Comments: This literature-non-study case concerns a 7-decade-old male patient, with medical history of ruptured left middle cerebral artery aneurysm, with residual right eye blindness and right leg weakness with gait instability, who experienced the unexpected serious (medically significant) ADR of GUILLAIN-BARRE SYNDROME. Patient received a dose of mRNA-1273 vaccine 3 days before symptom onset. Patient presented with loss of balance, weakness of his legs and fatigue for 3days. Approximately 4 weeks later patient was presented. CT of head and CT angiogram of the head and neck were performed and demonstrated no acute intracranial bleeding and no vascular abnormalities. With the findings of diffuse hyporeflexia and cerebrospinalfluid showing albumino-cytologicaldissociation, Guillain-Barre syndrome was high on the differentials. Electromyogram showed evidence of demyelination. He was treated with intravenous immune globulin (IVIG) and was discharged to rehab with complete symptom resolution. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.