Reply: "Spinal nerve pathology in Guillain-Barré syndrome associated with COVID-19 infection".

We are pleased to see the correspondence from Berciano and Gallardo with regard to our paper published in Muscle & Nerve. , We would like to thank them for their interest and positive comments. They clearly mentioned the pathophysiologic mechanisms of Guillain–Barré syndrome (GBS) in spinal nerves and we read their previous studies with great interest.

Gallardo et al showed involvement of spinal nerves with electrophysiologic, ultrasonographic, and pathologic findings in patients with early GBS. Correspondingly, magnetic resonance imaging (MRI) of our patient using short‐tau inversion recovery (STIR) sequences showed edema of the spinal nerves and corresponding rami, demonstrating proximal demyelination.

MRI using post‐contrast T1 sequences helps to demonstrate the topography of nerve root enhancement in GBS, but it is not applicable to patients with kidney failure or contrast allergies. We think that adding coronal STIR sequences to the imaging protocol is a useful method for the detection inflammatory edema of nerve roots and plexus. In STIR sequences, all structures with short T1 relaxation times are suppressed, whereas structures with high water content show a bright signal on a dark background and demonstrate the swollen spinal nerves and corresponding rami. The coronal plane is the most valuable plane in STIR images, because it demonstrates anatomic structures including proximal nerve segments in a familiar perspective.

Late‐response alterations (F wave and H reflex) are the most common early electrophysiologic findings supporting proximal demyelination in early GBS. , In our case, the increased chronodispersion and decreased persistence of F waves in the median and ulnar nerves can be caused by demyelination in any segment of the peripheral nerve, because nerve conduction studies revealed conduction blocks of median and ulnar nerves in the wrist‐elbow segment, and STIR images showed involvement of proximal nerve segments.

More investigations with electrophysiologic, radiologic, and pathologic studies will help further our understanding of the pathophysiologic mechanisms of GBS and elucidate therapeutic strategies.

CONFLICTS OF INTEREST

None of the authors has any conflict of interest to disclose.

ETHICAL PUBLICATION STATEMENT

We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

ABBREVIATIONS

GBS, Guillain–Barré syndrome; MRI, magnetic resonance imaging; STIR, short‐tau inversion recovery.