Review Question - QID 217670

This patient with a history of hyperlipidemia and hypertension who presents with acute weakness of the left hand, left lower facial droop, and dysarthria most likely has a lacunar infarct of the basis pontis (dysarthria-clumsy hand syndrome). Her positive pronator drift test indicates an upper motor neuron lesion while her intact Romberg test indicates intact proprioception.

Pronator drift is a pathologic sign seen in upper motor neuron lesions of the upper extremity. The test is performed by asking patients to flex the shoulder, extend the elbows, supinate the forearms, close their eyes, and maintain the position. Patients with slight weakness will begin to pronate their forearms and have downward motion of the affected limb. A positive test indicates a lesion to the contralateral pyramidal tract as the supinator muscles are weaker than pronator muscles in upper motor neuron lesions of the upper extremities. The Romberg test is used to assess the integrity of the proprioceptive sensory pathway. The test is performed by asking the patient to stand with feet together and close her eyes. If the patient becomes increasingly unsteady only after closing her eyes, the test indicates a proprioceptive defect. If patients are unable to stand stably erect with their eyes open and feet together, this indicates vestibular, vision somatosensory, or cerebellar disease. In these cases, the Romberg test should not be performed as it would offer no additional insight into proprioception.

Shahrokhi et al. discuss the utility and components of the neurological examination.

Incorrect Answers:
Answer 1: Lower motor neuron lesion and intact cerebellar function are incorrect as pronator drift is a test of upper motor neuron lesion pathology. The Romberg test assesses proprioception and not cerebellar function.

Answer 2: Lower motor neuron lesion and intact proprioception are incorrect as pronator drift is a test of upper motor neuron lesion pathology.

Answer 3: Upper motor neuron lesion and impaired cerebellar function are incorrect as the Romberg test assesses proprioception, not cerebellar dysfunction. This patient’s left-hand clumsiness is most likely due to weakness and not true cerebellar dysfunction.

Answer 4: Upper motor neuron lesion and intact cerebellar function are incorrect as the Romberg test assesses proprioception, not cerebellar dysfunction. This patient’s cerebellar function is intact but is better assessed by the finger-nose-finger and heel-to-shin tests.

Bullet Summary:
Pronator drift occurs in upper motor neuron lesions, whereas the Romberg test is used to evaluate defects in proprioception sensory pathways.