Diagnostic confusion resolved by being upbeat

Abstract

The classical stroke presentation - captured by the public health campaign mnemonic FAST (face, arm, speech, time) - does not apply in a large number of stroke cases; yet establishing a prompt diagnosis is imperative for optimal management. Here, we describe a patient with acute bulbar weakness, numbness in all extremities and an apparently normal magnetic resonance imaging (MRI) of the brain upon admission for whom even the fundamental question of whether this reflected a central or peripheral nervous system process was unclear. The critical localizing sign was upbeat nystagmus that denotes a brainstem cause. MRI of the brain in the second week confirmed a diagnosis of medial medullary infarction.

Figure 1

Representative MRI from the patient on admission shows a single voxel of hyperintensity on DWI in dorsal paramedian medulla, equivocal hypointensity of the equivalent apparent diffusion co-efficient (ADC) voxel and subtle hyperintensity of the medial medulla at the same time point. In the second week, a repeat MRI shows unequivocal T2 hyperintensity within a paramedian medullary distribution

Figure 2

Schematic neuroanatomy of the medulla showing, on the left side, the arterial supply and arterial territories (note similarity of medial medullary artery territory with patient's T2 lesion). On the right side, the most relevant anatomical structures for this case are shown, including nucleus intercalatus which acts as a neural integrator for vertical eye movements; medial lemniscus which conveys spinothalamic fibres; and nucleus ambiguus which conveys efferent vagal fibres to swallowing muscles