We present the case of a 27-year-old woman of Chinese nationality, who did not understand Spanish, had no known drug allergies, no medical or surgical history of interest and had been correctly vaccinated as a child in her country of origin. The patient first came to the emergency department of the health centre for a pruritic urticariform reaction of 24 hours' duration. At this first consultation she was prescribed an intramuscular antihistamine and a delayed-release corticoid and was diagnosed with urticaria.
One day later the patient returned to the emergency department with an increase in lesions, reporting intense itching of the face, scalp, trunk, upper limbs and genitals. Several polymorphous lesions with a widespread distribution were observed, with haemorrhagic crusty lesions and other vesicular-pustular lesions two to five millimetres in diameter, some of them umbilicated in the central area. In the central abdominal region there was a necrotic crusty lesion that the patient said she had handled. After examination, she was diagnosed with chickenpox. She was referred home after taking a smear of the lesions, explaining to her the respiratory isolation measures that should be taken with her non-immunised cohabitants. She was prescribed oral acyclovir 800 mg every four hours, five times a day, with nightly rest for seven days, and antihistamines.
Seven days later, our patient attended the emergency department of our referral hospital for intense asthenia of 24 hours' duration with no other symptoms. Examination was completely normal, so in the absence of any abnormalities in both laboratory and radiological tests, it was decided to discharge her home.
Twelve hours later, the patient returned to the emergency department with suprapubic pain and asthenia. In the anamnesis she reported dysuria of two days' evolution and oligoanuria, with no concomitant febrile process. Cardiopulmonary auscultation was completely normal. Abdominal examination revealed suprapubic pain with palpation of the bladder balloon with positive suction in both renal fossae. Suspecting acute urinary retention, a bladder catheterisation was performed, revealing an emptying of 1,200 cc. Blood and urine tests were performed with results within normal parameters. The abdominal X-ray showed the presence of abundant retained faecal debris.
During re-evaluation in the observation room, the companion-translator reported a clear improvement in abdominal pain and said that the patient had been suffering from progressive loss of strength and weakness in the lower limbs for four days. The patient was re-evaluated, with marked cervical stiffness, normal cranial nerves, distal and proximal motor balance 5/5 in the upper limbs. In the lower extremities, flaccid paraparesis with motor balance 3/5 proximal and 4/5 distal. Osteotendinous reflexes with bilateral patellar hyporeflexia and abolition of Achilles reflexes. Bilateral plantar cutaneous reflex in flexion. Hypo-sensitivity in metatarsals below D5 (breast).
In view of the presence of neurological alterations, a craniocerebral computerised axial tomography (CAT) scan was ordered, where no focal intracranial lesions were observed and the cerebrospinal fluid spaces, as well as the differentiation of grey matter and white matter, were normal.
Subsequently, a lumbar puncture was performed where clear fluid was observed and samples were sent for laboratory studies, and the patient was admitted to the neurology department with the diagnosis of suspected post-infectious incomplete transverse myelitis.
During his admission, a spinal magnetic resonance imaging (MRI) scan was performed, which showed an area of T2 hypersignal located at the level of the cervical spinal cord (C5-D1) with a small dilatation of the ependymal duct, most likely related to infectious myelopathy. The lesion showed mild hypointensity in T1. This confirmed the diagnosis of infectious myelitis in the cervical spinal cord.

CSF serology results for Borrelia, Brucella, syphilis, Epstein Barr virus (EBV), Cytomegalovirus (CMV), Herpes simplex virus (HSV) and Varicella zoster virus (VZV) were negative. Serum serology results were congruent with CSF, except for Varicella zoster virus which was positive. Human Immunodeficiency Virus serology was also requested with negative results. Therefore, her highly probable aetiological diagnosis was acute myelitis due to Varicella zoster virus (VZV) infection.
Since her admission, given the high suspicion of acute myelitis due to VZV, treatment was started with i.v. acyclovir for the first ten days with the addition of i.v. corticosteroid.
The patient experienced a slow but steady improvement, and finally, after a month of hospitalisation, the catheter was removed without any episode of acute urinary retention in the following days. On discharge she continued rehabilitation treatment.