A 30-year-old male, with a past medical history of unspecified lymphoproliferative disorder in childhood that was not active at the moment, presented with 7 days of fever, cough, fatigue, and a vesiculopapular rash in his lips and genitals. He reported having unprotected anal intercourse prior to the onset of symptoms. He was initially managed at home, but his symptoms worsened with weakness, difficulty swallowing, and inability to walk, which made him consult the emergency department. Monkeypox virus DNA was detected by real-time PCR of cutaneous lesion swabs, oropharyngeal swab, and serum. On day 1 after admission, he presented slurred speech and urinary retention, and was unable to move his legs. His clinical examination showed somnolence, bilateral miosis, bilateral peripheral facial weakness, dysarthria, paraplegia, positive bilateral Hoffmann sign, bilateral neutral plantar reflex, and a T6 sensory level for dull, pinprick, temperature, vibration, and proprioceptive sensations. Meningeal signs (including neck stiffness, jolt accentuation, and Brudzinski) were present.

Laboratory tests on admission showed elevated white blood cells count, elevated C-reactive protein, with normal renal function and liver chemistries. HIV serology was negative. Contrast-enhanced brain MRI showed extensive hyperintensities on T2/FLAIR, predominantly in the white matter of brain hemispheres, and in basal ganglia, anterior thalamus, internal capsules, frontal medial cortex, cerebral peduncles, and the entire pons, some of which had restricted diffusion, but only a mild contrast enhancement, and no compression. Contrast-enhanced spinal cord MRI showed a T2/STIR hyper-intense longitudinally extensive transverse myelitis comprising levels T1 to T12, with no enhancement or compression (Fig. 1). The lumbar puncture showed normal opening pressure (20 cm H2O), a clear CSF with mild elevated protein and lymphocytic pleocytosis (Table 1). Monkeypox virus real-time PCR in CSF was negative. Transverse myelitis laboratory workup was performed, with serum anti-AQP4 and anti-MOG negative for demyelinating etiologies, B12 vitamin, and other nutritional deficiencies were excluded, and infectious etiologies were also excluded through CSF analysis (Table 1).

Brain MRI. A Axial FLAIR showing hyperintensities in the right internal capsule (arrowhead) and left basal ganglia (arrow); B axial FLAIR showing diffuse hyperintensity of the pons (arrow); C coronal T2 with extensive hyperintensities of internal capsules (arrowhead), midbrain, and pons (arrow). Spinal cord MRI. D Sagittal STIR showing hyperintensity below C7 level of the spinal cord; E longitudinally extensive hyperintensity along the entire thoracic spinal cord; F axial T2 with transverse hyperintensity of the spinal cord (arrow)

ADEM was suspected due to clinical and radiological findings. Initially, he received symptomatic and supportive measures, but subsequently, he developed progressive loss of consciousness and respiratory failure, requiring invasive ventilatory support. Unfortunately, there were no antivirals for monkeypox available in Colombia by the time the patient was admitted; therefore, he was treated with systemic corticosteroids (methylprednisolone 1 g QD) for 5 days without concomitant antiviral treatment.

Patient’s neurological symptoms progressed in the following days with an abnormal conjugate gaze to the left with inability to abduct the right eye and nystagmus in the left eye, the bilateral peripheral facial palsy persisted, and he still did not have any respiratory drive. A new MRI showed increased hyperintensity of the previously involved structures such as the pons, midbrain, internal capsules, and basal ganglia, with a subtle increase in the size of the lesions.

It was decided to start adjunctive treatment with intravenous immunoglobulin (0.2 g/kg QD). On day 3 after initiation of IVIG, the patient presented with urinary tract infection that was treated with meropenem with an appropriate clinical response. The patient was weaned from mechanical ventilation and successfully extubated. After 4 weeks of the patient’s arrival and 3 weeks following completion of treatment, the clinical condition of the patient improved, with complete resolution of consciousness, he was able to communicate, cranial nerve involvement showed improvement in ophthalmoparesis, facial weakness and speech, sensory level was in T10, and all associated medical complications were controlled.