Introduction: Mycoplasma pneumoniae is a pathogen know as to the main causal agent of atypical pneumonia, as well as to generate different extrapulmonary sickness, especially in neurological ways, directing to the nervous system, thanks to all its different mechanisms, like: virulence, mimetysm and immunomodulation in to the host. Producing, pathologies like neuropathies, polyneuropathies, encephalopathies, Guillain Barré Syndrome. Objetives: To highlight in the pediatric area, the need to modificate diagnosis criteria and incorporate Guillain-Barre Syndrome clinicals variants, also instruments to diagnosis of neuropathic pathologies. Case presentation: Male patient, 9 years, 8 months old, who consulted in repeated occasions for: dyspepsia, diarrhea and constipation episodes and fiber. Confirmed according to consultation: dysbiosis, common cold, and finally, atypical pneumonia by Mycoplasma Pneumoniae. The patient evolves with: muscular weakness, hyperalgesia and allodynia of upper and inferior extremities. Then, the Neurologist, indicates neurophysiological exams (nerve conduction velocity, evoked potentials, discarding an electromyography, due to hyperalgesia). Diagnosing an axonal polyneuropathy. Which was characterized to present some same aspects, from clinical course of Guillain-Barre Syndrome. Highlighting that the clinical evolution, as also, the syndrome clinical variants, has it a course in adults, characterized by a different beginning and signs, than in children. Retarding and do a wrong diagnosis in pediatric patients. Conclusion: Lack of new diagnosis criteria, the amplitude of these and tools of approach to give a fast and effective diagnosis, and contribute to the optimal recovery of the patient.