Clinical Neuroscience Week 6 – Ascending Pathways (Very Hard)

A patient presents with selective loss of pain and temperature sensation, beginning several segments below the level of a spinal cord lesion, while retaining proprioception and vibration sense. Assuming a singular lesion, which vascular structure is most likely compromised, leading to this specific presentation?

Following a penetrating injury to the spinal cord, a patient exhibits ipsilateral loss of fine touch discrimination, vibratory sense, and proprioception, coupled with contralateral loss of pain and temperature sensation. At which level of the neuraxis did the most likely lesion occur, considering the observed sensory deficits and their respective pathways?

A patient demonstrates impaired proprioception in the right lower extremity, alongside diminished vibratory sensation, but exhibits intact light touch and two-point discrimination. Assuming a lesion along the ascending sensory pathways, where would you expect the lesion to be localized?

In a complete transection of the spinal cord at the T10 level, which of the following somatosensory modalities would remain intact bilaterally?

A patient with central cord syndrome exhibits disproportionately greater motor impairment in the upper extremities compared to the lower extremities, alongside a sensory deficit. What neuroanatomical feature of the corticospinal and spinothalamic tracts explains this clinical presentation?

A patient presents with loss of pain and temperature sensation starting several segments below the level of the lesion, but retains motor function, proprioception and light touch. Which pathway is MOST likely affected?

During a neurological examination, a clinician assesses a patient’s proprioception by passively moving the patient’s great toe and asking the patient to identify the direction of movement. Which of the following neural structures is LEAST directly involved in mediating this sensation?

After a spinal cord injury, a patient exhibits the following pattern of sensory loss: loss of pain and temperature sensation on the right side of the body, beginning a few segments below the level of the lesion, and loss of light touch, vibration and proprioception on the left side, all below the level of the lesion. Where is the injury most likely located?

In a patient presenting with Brown-Sequard syndrome following a penetrating injury to the right side of the spinal cord at the T10 level, which of the following neurological deficits would be MOST expected?

A researcher is investigating the effects of a novel neurotoxin that selectively targets and destroys second-order neurons within the spinothalamic tract. Which of the following outcomes would MOST likely be observed in animal models treated with this neurotoxin?

What is the underlying neuroanatomical basis for the characteristic pattern of motor and sensory deficits observed in central cord syndrome?

A patient exhibits dysmetria in the lower extremities, characterized by an inability to accurately control the range and force of movements during heel-tapping. Assuming this deficit arises from impaired proprioceptive input, which ascending spinal pathway is MOST likely implicated?

In a patient with confirmed anterior cord syndrome, which combination of clinical findings would MOST strongly support this diagnosis?

Following a spinal cord injury, a patient demonstrates impaired ability to perform rapid alternating movements with the upper extremities. Lesions to which ascending/descending pathway would possibly cause this?

A lesion exclusively affecting the spinotectal tract would MOST directly impair which of the following functions?

Which of the following scenarios would MOST strongly suggest a selective disruption of the spinoolivary tract?

Considering the somatotopic organization of the spinal cord, which of the following injury patterns would MOST likely result in greater motor impairment in the upper extremities compared to the lower extremities?

A researcher aims to develop a highly selective antagonist for the receptors of first-order neurons in the spinothalamic tract. Successful application of this antagonist would MOST directly lead to:

A patient with damage to the superior colliculus might have difficulty with what function?

Which ascending tract decussates in the medulla?

In the context of spinal cord injuries, which of these deficits would MOST indicate damage limited to lower motor neurons?

A researcher discovers a novel drug that selectively enhances the activity of second-order neurons in the spinoolivary tract. Which effect is MOST likely to be observed?

Which of the following clinical presentations would most strongly suggest a complete lesion of the cauda equina?

Following a complete spinal cord transection at the T4 level, a patient reports phantom sensations of light touch on their left foot. Which neuroanatomical mechanism BEST explains this phenomenon, considering known neuroplasticity and pathway redundancies?

A researcher discovers a novel neurotoxin that selectively targets and ablates A-delta fibers while sparing A-beta and C fibers. How would this toxin's effects manifest in a clinical sensory assessment?

In a patient with a lesion affecting the cuneate fasciculus at the C6 level, which sensory deficits would be MOST expected?

A patient presents with sensory ataxia, exhibiting impaired coordination despite normal strength. Neuroimaging reveals selective damage to the posterior spinocerebellar tract. Which clinical presentation would be MOST consistent with this finding?

A novel pharmacological agent selectively enhances the activity of inhibitory interneurons within the dorsal horn of the spinal cord. What effect would this agent MOST likely have on the perception of chronic pain?

A patient with a right MCA stroke exhibits left-sided hemiparesis and hemisensory loss. Which sensory modality would be MOST affected, and what cortical area is primarily implicated?

During a neurological examination, a patient demonstrates an inability to discriminate between two points separated by 6mm on their index finger, yet can accurately discriminate points separated by 40mm on their back. What neurophysiological principle BEST explains this difference?

A researcher is investigating the effects of a genetic mutation that disrupts the development of the gracile fasciculus. What specific sensory and motor deficits would be MOST anticipated in individuals with this mutation?

If a patient has damage to their spinotectal tract, what sensory-related function would be MOST affected?

A patient reports heightened sensitivity to normally innocuous stimuli (allodynia) following a nerve injury. Which mechanism is MOST likely contributing to this phenomenon at the level of the spinal cord?

Following a stroke affecting the thalamus, a patient develops severe, intractable pain on the contralateral side of their body (thalamic pain syndrome). Which neuroanatomical mechanism BEST explains this condition?

A person has a spinal cord injury that specifically damages the anterior spinocerebellar tract. How would this MOST likely present?

During a sensory assessment, a patient accurately reports the direction of joint movement when their elbow is passively moved through a large arc, but struggles to detect movement when the arc is small. What aspect of proprioceptive processing is MOST likely impaired?

A novel virus selectively infects and destroys only the 2nd order neurons of the DCML pathway. What specific sensory deficits would MOST likely result from this infection?

A researcher is investigating the role of the amygdala in pain perception. What aspect of pain processing would be MOST affected by lesions to this structure?

A patient presents with diminished vibratory sense and impaired conscious proprioception in the right lower extremity, while pain and temperature sensation are intact. Magnetic resonance imaging reveals a lesion affecting a single ascending pathway within the spinal cord. Assuming the lesion is completely contained within the spinal cord, which specific anatomical structure is MOST likely involved?

Consider a scenario where a researcher selectively ablates the dorsal root ganglia corresponding to the C6 dermatome on one side only in an animal model. Which sensory deficit would MOST accurately reflect the expected outcome of this ablation?

A patient exhibiting Brown-Séquard syndrome demonstrates ipsilateral deficits in motor function, fine touch, vibratory sense and proprioception, along with contralateral deficits in pain and temperature sensation beginning a few levels below the lesion. Assuming complete hemisection of the spinal cord, what specific mechanism BEST explains the pain and temperature deficits observed several levels below the lesion?

Following a spinal cord injury, a patient reports a selective loss of discriminative touch while retaining the ability to detect crude touch and pressure. Assuming a lesion affecting a single ascending pathway, which specific tract is MOST likely compromised?

A neuroanatomist discovers a novel variant of sensory neuron in a primate model. These neurons express receptors sensitive to rapidly changing thermal gradients. These neurons synapse exclusively within the dorsal horn, and their axons immediately decussate and ascend within the spinal cord. If these axons were selectively lesioned, which sensory deficit would MOST likely be observed?

Afferent/Sensory Input

Dorsal Column-Medial Lemniscus (DCML)

Spinothalamic Tract

Conscious Proprioception

Lateral Spinothalamic Tract (LST)

DCML Pathway

Gracile fascicle

Cuneate fascicle

1st order neuron (DCML)

2nd order neuron (DCML)

3rd order neuron (DCML)

Proprioception

Ventral spinothalamic tract (VST)

1st order neuron (Spinothalamic)

2nd order neuron (Spinothalamic)

A-delta fibers

C fibers

Spinocerebellar Tracts

Posterior spinocerebellar tract

Anterior spinocerebellar tract

DCML functions

Cauda Equina Syndrome

Anterior Cord Syndrome

Central Cord Syndrome

Brown-Sequard Syndrome

Assessing Light Touch

Assessing Vibration

Spinotectal Tract

Spinoolivary Tract

Corticospinal Tracts

Extrapyramidal Tracts

DCML (Dorsal Column Medial Lemniscus)

Medulla

Dorsal Horn

Medulla

Thalamus