In a Patient With Pre‐Existing Tetraparesis, GBS Should Be Diagnosed Only if All Differential Causes Have Been Ruled Out

ABSTRACT

In a patient with pre‐existing proximal tetraparesis, progression to the distal limb muscles after 3 years should be attributed to Guillain‐Barre syndrome only if differential causes of tetraparesis were thoroughly ruled out.

To the Editor,

The paper by Abusaada et al. about a 7‐year‐old boy who had been suffering from proximal tetraparesis since the age of 4 is insightful [1]. At age 7, his condition deteriorated acutely, and the proximal muscle weakness spread to the distal limb muscles, leading to a diagnosis of Guillain‐Barré syndrome (GBS) of the “acute motor axonal neuropathy” (AMAN) subtype [1]. Since the patient had been diagnosed with malaria 3 weeks before the worsening of the tetraparesis, malaria‐induced AMAN was diagnosed. Administration of intravenous immunoglobulins (IVIG) resulted in a return to the condition prior to the current exacerbation [1]. The study is compelling, but there are points that should be discussed.

First, the diagnosis of GBS is not convincing [1]. The patient had suffered from proximal tetraparesis of unknown cause since the age of 4 [1]. Therefore, it cannot be ruled out that the worsening of the tetraparesis and the involvement of the distal musculature merely represented an exacerbation of the pre‐existing tetraparesis during the acute infection [2]. The findings that led to the diagnosis of AMAN could also be explained by other causes. Elevated cerebrospinal fluid (CSF) protein levels are generally non‐specific and may be related to the pre‐existing tetraparesis or the recent infections. The findings from the nerve conduction studies (NCS) could also have been present previously and bear no relation to the deterioration that occurred at age 7. Had the patient undergone CSF analysis or NCS prior to the current evaluation? It is also recommended to present the results of follow‐up CSF and NCS conducted after the patient recovered from the deterioration that occurred at age 7. If elevated CSF protein levels and axonal lesions persisted even after clinical recovery from the pre‐infectious condition, this is more likely attributable to the pre‐existing neurological disorder than to the new onset of deterioration at age 7. The observed effect of IVIG could also be due to a spontaneous course of the neuropathy.

Secondly, the pre‐existing proximal tetraparesis was not sufficiently investigated [1]. To assess whether the acute deterioration is causally related to the pre‐existing neurological problem, it would be useful to identify the etiology of the proximal tetraparesis that persisted since the age of 4. Was the cause a problem of the central nervous system (CNS) or the peripheral nervous system (PNS)? Did the patient undergo a neurologicak examination at the age of 4? Were the tendon reflexes already diminished at the age of 4? Was there evidence of muscle hypotonia or muscle atrophy at the age of 4? Needle electromyography could have been helpful in differentiating whether a PNS lesion was myogenic or neurogenic.

Third, assuming the patient did indeed suffer from GBS, it would have been useful to identify the trigger of GBS. Bacteria, viruses, or protozoa, vaccinations, trauma, surgery, immune disorders, and sepsis are known to trigger GBS [3]. Since the index patient not only tested positive for malaria but also had a flu‐like infection 2 weeks prior to admission, it would have been essential to rule out all viral infections as triggers of GBS. Testing for infections with enteroviruses, adenoviruses, herpesviruses, cytomegalovirus, flaviviruses, measles virus, SARS‐CoV‐2, and tick‐borne encephalitis would have been mandatory [3].

Fourth, the detection of elevated ganglioside antibodies could have supported the diagnosis, as GBS is frequently associated with variable patterns of elevated ganglioside antibodies [4].

Overall, in a patient with pre‐existing proximal tetraparesis, the diagnosis of GBS can be more reliably made if the cause of the previous neurological condition has been identified.

Author Contributions

Sounira Mehri: investigation, validation, writing – review and editing. Josef Finsterer: conceptualization, investigation, writing – original draft, writing – review and editing, validation.

Funding

The authors have nothing to report.

Ethics Statement

The authors have nothing to report.

Consent

The authors have nothing to report.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.