An Uncommon Case of Acute Motor Axonal Neuropathy Variant of Guillain-Barré Syndrome: A Case Report

Case Diagnosis: Acute motor axonal neuropathy variant of GBS

Case Description or Program Description: A 24-year-old female presented after four days of progressively worsening, acute onset upper and lower extremity weakness worse distally than proximally, unable to ambulate independently by the time of presentation. Ten days prior to onset of weakness, she reported mild upper airway congestion without associated symptoms. Exam revealed pharyngeal erythema, symmetric weakness in distal upper and lower extremities, intact sensation to light touch bilaterally, and hyperreflexia. CSF obtained showed mildly elevated protein. MRI of lumbar spine demonstrated diffuse avid enhancement of cauda equina consistent with findings in Guillain-Barré Syndrome (GBS). Inpatient NCS/EMG (six days after symptom onset) revealed early findings concerning for the acute motor axonal neuropathy (AMAN) variant of GBS. Antibody panel, including anti-GM, GD1a, GD1b, and GQ1b were negative. Patient completed five-day course of IVIG and was discharged to acute rehabilitation during which she made functional gains over two weeks.

Setting: PM&R consult service

Assessment/Results: Repeat NCS/EMG performed approximately a month after symptom onset revealed acute/active denervation changes consistent with severe axonal polyneuropathy, along with interval reduction in CMAP, reaffirming suspected diagnosis of AMAN variant of GBS. Patient seen in the PM&R clinic one month after discharge from inpatient rehabilitation, where she demonstrated functional improvement to a modified independent level for ADLs and ambulation, with continued deficits in endurance and walking distance.

Discussion (relevance): This report shows a mild case of AMAN, a variant of GBS that is relatively uncommon in the United States. Contrary to the diagnostic criterion of areflexia, some GBS subtypes may present with preserved or even brisk reflexes. This can lead to diagnostic challenges if clinicians are not aware of these variations.

Conclusions: The presence of preserved reflexes, particularly in the context of suspected GBS, should not rule out the diagnosis, especially if other clinical and electrophysiological features suggest an axonal variant.