This supplementary appendix provides additional information about the cases of Guillain–Barré syndrome (GBS) associated with SARS-CoV-2, as reported by Toscano et al. in the New England Journal of Medicine. The appendix includes detailed case histories, supplementary figures, and tables. 1. **Case 1**: A 77-year-old woman developed paresthesia in the lower limbs and hands, followed by flaccid areflexic tetraplegia. She had a fever, cough, and decreased sense of taste. RT-PCR confirmed SARS-CoV-2 infection. EMG showed axonal GBS with sparing of the sural nerve. IVIg treatment initially worsened her condition but showed some improvement later. 2. **Case 2**: A 23-year-old male experienced bilateral facial weakness, mastoid pain, loss of taste, and lower limb paresthesia. He had a fever and sore throat. MRI showed focal contrast enhancement at the internal acoustic meatus. EMG revealed axonal sensory-motor damage. IVIg treatment improved facial weakness and limb paresthesia. 3. **Case 3**: A 55-year-old male presented with fever, cough, neck pain, paresthesia, and lower limb weakness. CT scan showed interstitial pneumonia. EMG showed severe axonal neuropathy. IVIg treatment led to facial diplegia and respiratory failure, requiring ICU admission. 4. **Case 4**: A 76-year-old male complained of dry cough and loss of smell, followed by lumbar pain and lower limb weakness. He developed flaccid areflexic tetraparesis. IVIg treatment improved motor function, but he remained unable to stand. 5. **Case 5**: A 61-year-old male experienced asthenia, dry cough, loss of taste and smell, and lower limb paresthesia. He developed generalized areflexia and paraparesis. EMG showed conduction blocks and demyelination. IVIg treatment worsened his condition, leading to respiratory failure and mechanical ventilation. - **Figure S1**: Timelines showing the onset of general and neurological symptoms, hospital admission, IVIg therapy, and neurological improvement or worsening. - **Table S1**: Neurophysiological features of the patients, including nerve conduction studies and EMG findings. - **Table S2**: Demographic features of the patients and details of non-neurological features, including SARS-CoV-2 IgG testing. The authors acknowledge "San Giorgio Labs srl" for their collaboration in detecting SARS-CoV-2 IgG.This supplementary appendix provides additional information about the cases of Guillain–Barré syndrome (GBS) associated with SARS-CoV-2, as reported by Toscano et al. in the New England Journal of Medicine. The appendix includes detailed case histories, supplementary figures, and tables. 1. **Case 1**: A 77-year-old woman developed paresthesia in the lower limbs and hands, followed by flaccid areflexic tetraplegia. She had a fever, cough, and decreased sense of taste. RT-PCR confirmed SARS-CoV-2 infection. EMG showed axonal GBS with sparing of the sural nerve. IVIg treatment initially worsened her condition but showed some improvement later. 2. **Case 2**: A 23-year-old male experienced bilateral facial weakness, mastoid pain, loss of taste, and lower limb paresthesia. He had a fever and sore throat. MRI showed focal contrast enhancement at the internal acoustic meatus. EMG revealed axonal sensory-motor damage. IVIg treatment improved facial weakness and limb paresthesia. 3. **Case 3**: A 55-year-old male presented with fever, cough, neck pain, paresthesia, and lower limb weakness. CT scan showed interstitial pneumonia. EMG showed severe axonal neuropathy. IVIg treatment led to facial diplegia and respiratory failure, requiring ICU admission. 4. **Case 4**: A 76-year-old male complained of dry cough and loss of smell, followed by lumbar pain and lower limb weakness. He developed flaccid areflexic tetraparesis. IVIg treatment improved motor function, but he remained unable to stand. 5. **Case 5**: A 61-year-old male experienced asthenia, dry cough, loss of taste and smell, and lower limb paresthesia. He developed generalized areflexia and paraparesis. EMG showed conduction blocks and demyelination. IVIg treatment worsened his condition, leading to respiratory failure and mechanical ventilation. - **Figure S1**: Timelines showing the onset of general and neurological symptoms, hospital admission, IVIg therapy, and neurological improvement or worsening. - **Table S1**: Neurophysiological features of the patients, including nerve conduction studies and EMG findings. - **Table S2**: Demographic features of the patients and details of non-neurological features, including SARS-CoV-2 IgG testing. The authors acknowledge "San Giorgio Labs srl" for their collaboration in detecting SARS-CoV-2 IgG.