A 65-year-old man is evaluated for right lower extremity weakness and difficulty walking. The patient has a history of hypertension, type 2 diabetes mellitus, and osteoarthritis. He has smoked a pack of cigarettes daily for 30 years. During physical examination, the lateral border of his right sole is stroked using the blunt tip of a reflex hammer. The maneuver, starting near the heel and proceeding to the base of the fifth toe, elicits extension of the great toe and fanning out of the other toes. Which of the following additional findings is most likely to be observed in this patient's right lower extremity?

Question

A 65-year-old man is evaluated for right lower extremity weakness and difficulty walking.  The patient has a history of hypertension, type 2 diabetes mellitus, and osteoarthritis.  He has smoked a pack of cigarettes daily for 30 years.  During physical examination, the lateral border of his right sole is stroked using the blunt tip of a reflex hammer.  The maneuver, starting near the heel and proceeding to the base of the fifth toe, elicits extension of the great toe and fanning out of the other toes.  Which of the following additional findings is most likely to be observed in this patient's right lower extremity?

Quizplus · Accepted Answer

11ec160b_3b07_a263_9249_af067e3e9163_MD0001_00 The plantar reflex (Babinski sign) is assessed by firmly stroking the plantar surface of the lateral foot from the heel to the ball. Plantar flexion of the toes is normal; dorsiflexion with or without fanning of the toes is considered abnormal and indicates an upper motor neuron lesion. Children age <12 months also exhibit a positive response, which is considered normal and reflects incomplete myelination of the corticospinal tract. Upper motor neurons (UMNs) originate in the cerebral cortex and are responsible for the initiation of voluntary movement. UMN fibers travel through the brainstem and spinal cord to reach lower motor neurons (eg, cranial nerves, spinal nerves), which then innervate muscle fibers. UMN injury can occur anywhere proximal to the anterior horn; common etiologies include stroke (which likely occurred in this patient with multiple risk factors), multiple sclerosis, or spinal cord transection. Other signs of UMN injury include hyperreflexia, spastic paralysis, increased muscle tone, clasp-knife rigidity (increased muscle tension with sudden release on passive flexion), and pyramidal weakness (weakness is more pronounced in lower extremity flexors and upper extremity extensors). Upper extremity supination is also typically weaker than pronation, resulting in pronator drift. (Choices A and E) Lower motor nerve lesions are most commonly due to trauma involving the peripheral nerves. Manifestations include muscle weakness/paralysis with hypotonia, suppressed or absent deep tendon reflexes, and muscle atrophy. Fasciculations (brief, spontaneous contractions of small groups of muscle fibers) also occur due to denervation of the affected muscles. However, the plantar reflex in lower motor lesions will be downgoing or indifferent (ie, no response). (Choice C) Cogwheel rigidity (increased muscle rigidity with rhythmic interruptions noted on passive limb movement) is seen with lesions in the extrapyramidal tracts, which modulate motor neuron activity. This sign is classically seen in Parkinson disease. (Choice D) In upper motor neuron lesions, lower extremity weakness is typically more pronounced in the flexors than the extensors. Educational objective: Upper motor neuron signs include abnormal plantar flexion (Babinski sign), spastic paralysis, increased muscle tone, clasp-knife rigidity, hyperreflexia, pronator drift, and pyramidal weakness (weakness more pronounced in lower extremity flexors and upper extremity extensors). Lower motor neuron signs include flaccid paralysis, weakness with hypotonia and muscle atrophy, fasciculations, and suppressed or absent reflexes.

A 65-Year-Old Man Is Evaluated for Right Lower Extremity Weakness