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ACEP Now: Vol 40 – No 07 – July 2021

Figure 1: In the Mingazzini sign (top), a standing or seated patient raises their arms with fingers spread and holds the position for 30 seconds. The affected arm will lower. In the Mingazzini maneuver (bottom), a supine patient flexes the hips so their thighs are at right angles to the trunk and the lower legs are horizontal and holds the position for 30 seconds. The affected thigh will lower.
ellepigrafica – stock.adobe.com

Step 4: Explore Associated Findings

There are five key associated findings that may accompany motor power loss that can help localize the lesion and narrow the differential diagnosis. Absence of reflexes suggests a peripheral neuropathy such as Guillain-Barré syndrome. Bladder dysfunction associated with loss of motor power is invariably caused by a spinal cord lesion. Bulbar symptoms such as diplopia, dysarthria, and dysphagia point to a brain stem lesion. To distinguish a left versus right cerebral cortex lesion, dysphasia suggests the former, while hemispatial and/or sensory neglect suggest the latter. Hemispatial neglect is sometimes obvious based on observation alone, but visual field testing confirms the finding.⁶ The “double extinction test” assesses for the presence of hemisensory neglect. This test is performed by tapping on the patient’s forearm on one side while asking which side they are able to feel the tap, right or left.⁷ The test is then repeated on the other side. Finally, both forearms are tapped simultaneously. The patient with hemisensory neglect will report sensation only on the non-neglected side.

Step 5: Distinguish Upper Versus Lower Motor Neuron Weakness

Clinical examination can distinguish between upper and lower motor neuron pathology. A Babinski reflex and increases in reflexes are seen with upper motor neuron lesions, while decreased or absent reflexes are associated with lower motor neuron lesions. An assessment of the degree and speed of movement may help distinguish upper from lower motor neuron disease.^8,9 Lower motor neuron disease weakness is generally more pronounced than upper motor neuron disease weakness. For example, the loss of power one gets as a result of a peripheral neuropathy, such as a foot drop, is generally more severe than the loss of power one gets from a central nervous system stroke. Another distinguishing feature is the speed of movement: While lower motor neuron lesions do not affect the speed of motor movement, upper motor neuron lesions usually result in slow movements, sometimes referred to as corticospinal tract slowness. To test motor speed, ask the patient to tap their foot or roll their forearms around one another at an increasing tempo.