A Rare Case with New Insights: Pure Sensory Guillain Barre Syndrome with Axonal Features

The pure sensory variant of Guillain-Barré syndrome "GBS" is controversial. Scarce case reports in the literature have described pure sensory presentations secondary to acute demyelination of peripheral sensory nerves. Pure sensory GBS secondary to axonal damage is rarer and even more controversial owing to a significant overlap with sensory neuronopathy. A 31-year-old lady with history of a recent primary varicella zoster virus (VZV) infection presented with acute onset of sensory symptoms and signs involving her four limbs and the trunk, without weakness. Examination was remarkable for severe impairment in all sensory modalities in her limbs and trunk, pseudo-athetoid limb movements, sensory ataxia, positive Romberg's sign, and areflexia, with no motor involvement. CSF analysis showed elevated protein without pleocytosis known as albuminocytological dissociation. MRI of the spine with contrast showed multiple root enhancement. Nerve conduction studies "NCS" demonstrated absent sensory action potentials, with normal motor nerves responses. Initial electromyography was normal. After differential diagnoses were appropriately excluded, the patient was diagnosed with pure sensory axonal GBS and treated with IVIG for five days. Gradual clinical improvement was seen over the following months, with improvement in six-month GBS disability score down to two. Follow-up NCS showed findings similar to the initial study but follow-up EMG studies revealed denervation potentials in multiple levels, suggesting a subclinical axonal motor involvement and excluding sensory neuronopathy. To our best knowledge, this case represents the first case of pure sensory GBS with onset after a documented primary VZV infection. The findings in this case illustrate the difficulties in diagnosing pure sensory GBS and the significance of an early treatment. It also demonstrates the potential value of follow-up EMGs in excluding sensory neuronopathy as an important differential diagnosis for this condition.