We read with interest the article by Nagalli et al. about a 49 years-old female who developed lower limb weakness 10 days after the first dose of the mRNA-1274 (Moderna) anti-SARS-CoV-2 vaccine [1]. Muscle weakness progressed to the upper limbs and the respiratory muscles resulting respiratory insufficiency with the need for mechanical ventilation [1]. The patient was diagnosed with SARS-CoV-2 induced Guillain-Barre syndrome (GBS) not earlier than eight weeks after onset of muscle weakness [1]. The patient benefitted from plasmaphereses and reached partial recovery at discharge to a rehabilitation facility [1]. The study is appealing but raises concerns that need to be discussed.

We do not agree with the notion that GBS had a “subacute” onset as indicated in the title [1]. Distal lower limb weakness started 10 days after the vaccination, corresponding to an acute onset. We thus also disagree with the speculation in the abstract that the patient could have had chronic inflammatory demyelinating polyneuropathy (CIDP) [1]. 

It is unclear according to which criteria GBS was diagnosed [1]. Most commonly, the Brighton criteria are applied but GBS can be also diagnosed according to the Ashford, Besta, or Hadden criteria. Application of the Brighton criteria may prevent diagnostic uncertainty.

A further limitation is that the subtype of GBS was not specified. According to the presented findings of nerve conduction studies (NCSs) the patient had acute, motor and sensory, axonal neuropathy (AMSAN) [1]. Knowing the GBS subtype is crucial as the therapeutic management and outcome may vary significantly between the various subtypes. Patients with sensory and autonomic involvement usually have a worse outcome as compared to patients with only motor involvement [2]. 

A shortcoming of the imaging studies of the cervical, thoracic, and lumbar spine is that no contrast medium was applied. GBS cases may show enhancement of the nerve roots as has been repeatedly reported [3]. Ultrasound, particularly of the cervico-brachial nerve roots, frequently shows enlargement of ventral rami of C5-C7 nerves with blurred boundaries [4]. 

Another limitation of the study is that an infection with SARS-CoV-2 was not definitively excluded. No information is provided whether the patient had a history of previous SARS-CoV-2 infection or if a PCR–test had been ever carried out. Since hundreds of cases with SARS-CoV-2 associated GBS have been reported during the last two years since outbreak of the pandemic, it is crucial that a SARS-CoV-2 infection as the underlying cause of GBS had been appropriately excluded in the index patient.