A 62-year-old woman comes to the emergency department due to difficulty walking that started 3 hours ago. The patient cannot feel the right side of her body. She has a history of hypertension and diabetes mellitus. She has smoked a pack of cigarettes daily for the past 30 years. The patient's father had a myocardial infarction at age 60. Physical examination shows loss of touch, temperature, and vibratory sensation affecting the right upper and lower extremities. Sensation is also diminished over the right side of the face. Muscle strength is 5/5 throughout. This patient has most likely suffered a stroke affecting which of the following brain structures?

Question

A 62-year-old woman comes to the emergency department due to difficulty walking that started 3 hours ago.  The patient cannot feel the right side of her body.  She has a history of hypertension and diabetes mellitus.  She has smoked a pack of cigarettes daily for the past 30 years.  The patient's father had a myocardial infarction at age 60.  Physical examination shows loss of touch, temperature, and vibratory sensation affecting the right upper and lower extremities.  Sensation is also diminished over the right side of the face.  Muscle strength is 5/5 throughout. This patient has most likely suffered a stroke affecting which of the following brain structures?

Quizplus · Accepted Answer

This patient with right-sided pure hemisensory loss has likely suffered from a thalamic stroke. The thalamic ventral posterior lateral nucleus (receives input from the spinothalamic tract and dorsal columns) and ventral posterior medial nucleus (receives input from the trigeminal pathway) send somatosensory projections to the cortex via thalamocortical fibers. Damage to these nuclei (eg, due to ischemia, hemorrhage) may result in complete contralateral sensory loss (eg, touch, pain/temperature, vibration/proprioception). Severe proprioceptive defects may cause unsteady gait. (Choice A) Injury to the base of the pons is frequently associated with contralateral weakness and ataxia due to involvement of the descending motor tracts (eg, corticospinal, corticobulbar) and pontocerebellar fibers. (Choice B) Damage to the caudate nucleus typically causes behavioral abnormalities (eg, agitation, psychosis, abulia), speech/language disturbances, and movement disorders (eg, choreoathetosis). (Choice C) Frontal cortex lesions usually cause social disinhibition and deficits in attention and executive function (eg, planning, organizing, decision making). (Choice D) The anterior two-thirds of the posterior limb of the internal capsule is mainly composed of motor fibers (eg, corticospinal tract), and the posterior one-third contains sensory fibers (eg, thalamocortical tract). Although very small lesions to the posterior limb may cause contralateral pure sensory deficits, most lesions result in pure motor or combined sensorimotor deficits. Educational objective: The ventral posterior lateral nucleus (receives input from the spinothalamic tract and dorsal columns) and ventral posterior medial nucleus (receives input from the trigeminal pathway) of the thalamus send somatosensory projections to the cortex via thalamocortical fibers. Damage to these nuclei results in complete contralateral sensory loss. __________ References: Pure sensory stroke. Clinical-radiological correlates of 21 cases. (http://www.ncbi.nlm.nih.gov/pubmed/1615549)

A 62-Year-Old Woman Comes to the Emergency Department Due to Difficulty