[Guillain-Barré syndrome caused by intravesical instillation of Bacillus Calmette-Guérin].

<p style="text-align: justify;"><strong>Introduction</strong> - Guillain-Barr&eacute; syndrome (GBS) is an acute inflammatory demyelinating polyneuropathy. In the vast majority of patients, 1-4 weeks before the onset of GBS-related symptoms, an event such as upper respiratory tract or gastrointestinal tract infection, surgical intervention or vaccination is present. To the best of our knowledge, this is the first case of GBS that occurred after intravesical Bacillus Calmette-Gu&eacute;rin (BCG) therapy in the absence of tuberculosis or any other infection in the English literature.<br><strong>Case report</strong> &ndash; A 65-year-old male patient, who had no systemic disorders except hypertension and coronary artery disease, underwent transurethral resection of a bladder tumour further to imaging studies investigating macroscopic haematuria. A pathologic examination revealed a non-muscle-invasive high-grade (pT1HG) transitional cell carcinoma. Immediately after the fourth cycle of intravesical BCG, which was administered 2 months after surgery, the patient experienced numbness and weakness in his lower and upper extremities, respectively. There were no signs or symptoms related to an acute cranial pathology or infectious disease. Nerve conduction studies, which were carried out on the 7th day after the onset of the neurologic symptoms, revealed a demyelinating sensorimotor polyneuropathy with mild secondary axonal damage in upper and lower limbs with a sural sparing pattern.<br><strong>Conclusion </strong>- Without tuberculosis infection, GBS can occur secondary to increased immune response and antibodies triggered by intravesical BCG therapy. However, considering the worldwide use of BCG vaccination and thousands of intravesical BCG therapies, this is a very rare adverse effect.&nbsp;</p>.