A crossed brain stem syndrome without crossed sensory symptomatology.

Lateral medullary infarction (LMI) or Wallenberg syndrome is a type of brain stem stroke, more specifically, a type of crossed brain stem syndrome. LMI is a well-described entity with several documented typical characteristics including pain and temperature impairment in the ipsilateral to the lesion side of the face and the contralateral side of the trunk and limbs. We present a case of LMI which describes a patient who presented with atypical features of analgesia and thermanaesthesia on the contralateral side of the face and absence of sensory deficit on the ipsilateral side. We attributed this pattern of involvement to a lesion that affects the ventral trigeminothalamic tract and spares the dorsolateral part of the medulla where the spinal trigeminal tract and its nucleus lie. This case report highlights the presence of atypical presentations of LMI that may initially challenge the physician's diagnostic reasoning.