Ulnar sensory-motor amplitude ratio: a new tool to differentiate ganglionopathy from polyneuropathy Razão de amplitude sensitivo-motora ulnar: novo parâmetro para diferenciar ganglionopatia de polineuropatia

Ganglionopathies (GNP), also known as sensory neuronopathies, are a group of conditions characterized by primary and selective damage to the dorsal root ganglia (DRG) of the spinal cord and sensory nuclei of the brainstem1,2. The etiologies are diverse and include immune-mediated diseases, vitamin deficiencies, drug toxicity, paraneoplastic syndromes and genetic causes, but many patients are yet defined as idiopathic1,2. The clinical presentation is characterized by diffuse, often asymmetric, sensory deficits and marked ataxia due to loss of proprioception1,2. In neurological practice, it is important to differentiate GNP from polyneuropathies (PNP) because the etiologies, therapeutic strategies and prognosis are often diverse3. Clinically, GNP can be distinguished from PNP due to a purely sensory dysfunction and the absence of length-dependent gradient of involvement. Often it is not possible to define a clear pattern of symmetry or predominant distal involvement (either by clinical or electrophysiological criteria), making it difficult to distinguish a GNP from a sensory PNP.