Lesion Localization Quiz: 15 Clinical Questions
Updated
Lesion localization relies on matching specific deficits to neuroanatomical pathways. Cortex causes higher-order deficits, internal capsule causes dense hemiparesis, brainstem causes crossed findings, spinal cord causes level-specific deficits, and cerebellum causes ataxia.
This quiz tests your ability to localize neurological lesions based on clinical deficits. It covers the cerebral cortex, internal capsule, brainstem, spinal cord, and cerebellum, with 15 vignettes ranging from common syndromes to more challenging cases. Ideal for medical students, neurology residents, and anyone reviewing neuroanatomy. Each question is followed by a brief explanation of the correct answer.
The key principle is that lesion location determines the pattern of deficits. Cortical lesions cause selective higher-order or focal motor/sensory deficits; internal capsule lesions produce dense hemiplegia; brainstem lesions often cause ipsilateral cranial nerve and contralateral long tract signs; spinal cord lesions produce a sensory or motor level; cerebellar lesions cause ipsilateral ataxia. Understanding these patterns allows accurate localization.
The questions
A 65-year-old man has sudden onset of weakness of the right face and right arm, with sparing of the right leg. Speech is slurred but comprehension is intact. Where is the most likely lesion?
A patient speaks fluently but uses nonsensical words and cannot understand spoken or written language. Where is the lesion?
A 45-year-old woman has difficulty producing speech. She speaks slowly with effort, and her speech is telegraphic, but she can understand others. She also has weakness of the right arm. Where is the lesion?
A 70-year-old man has sudden onset of dense right hemiplegia affecting the face, arm, and leg equally. Reflexes are brisk on the right with a Babinski sign. Where is the lesion?
A patient has difficulty with coordination in the right arm and leg, with past-pointing and intention tremor when reaching. Where is the most likely lesion?
A patient has a wide-based unsteady gait, falls frequently, and has nystagmus. Limb coordination is relatively normal. Where is the lesion?
A patient has bilateral loss of pain and temperature sensation below the level of the umbilicus, but fine touch and proprioception are intact. Where is the lesion?
A patient has loss of proprioception and vibration in the right leg, and loss of pain and temperature in the left leg. Where is the lesion?
A patient has a right homonymous hemianopia with macular sparing. Where is the most likely lesion?
A patient has difficulty performing learned motor tasks such as using a comb or brushing teeth, despite having normal strength and coordination. Where is the lesion?
A patient has profound anterograde amnesia, unable to form new memories, but can recall events from years ago. Where is the most likely lesion?
A patient has a left third nerve palsy (ptosis, dilated pupil, eye deviated down and out) and right hemiplegia. Where is the lesion?
A patient has loss of pain and temperature on the left side of the face, and loss of pain and temperature on the right side of the body, along with ataxia and a left Horner's syndrome. Where is the lesion?
A patient has a resting tremor, bradykinesia, and rigidity, predominantly on the right side. Where is the most likely lesion?
A patient has sudden onset of flaccid paralysis of both legs, loss of pain and temperature below the level of the lesion, but preservation of proprioception and vibration. Where is the lesion?
0 of 15 answered · 0 correct
Cheat sheet: key terms
| Motor homunculus | Face and arm are lateral in motor cortex; leg is medial. Lesion causes contralateral weakness in corresponding area. |
|---|---|
| Wernicke's area | Posterior superior temporal gyrus; damage causes fluent aphasia with poor comprehension. |
| Broca's area | Inferior frontal gyrus; damage causes non-fluent aphasia with preserved comprehension. |
| Internal capsule | Dense white matter tract; lesion causes contralateral hemiplegia affecting face, arm, leg equally. |
| Cerebellar signs | Ipsilateral ataxia, dysmetria, intention tremor; midline lesions cause truncal ataxia and nystagmus. |
| Spinal cord tracts | Dorsal columns: proprioception/vibration ipsilateral; spinothalamic: pain/temp contralateral (crosses in cord). |
| Brainstem cross | Brainstem lesions often cause ipsilateral cranial nerve palsy and contralateral hemiplegia or sensory loss. |
| Brown-Sequard syndrome | Hemisection of cord: ipsilateral proprioception loss and contralateral pain/temp loss. |
Answers explained
Show all 15 answers
- A 65-year-old man has sudden onset of weakness of the right face and right arm, with sparing of the right leg. Speech is slurred but comprehension is intact. Where is the most likely lesion? Left motor cortex (lateral aspect). The motor homunculus maps face and arm to the lateral motor cortex. A right-sided weakness sparing the leg suggests a left lateral motor cortex lesion.
- A patient speaks fluently but uses nonsensical words and cannot understand spoken or written language. Where is the lesion? Wernicke's area. Fluent paraphasic speech with poor comprehension is characteristic of Wernicke's aphasia, caused by damage to Wernicke's area.
- A 45-year-old woman has difficulty producing speech. She speaks slowly with effort, and her speech is telegraphic, but she can understand others. She also has weakness of the right arm. Where is the lesion? Left inferior frontal gyrus (Broca's area) and adjacent motor cortex. Broca's aphasia is non-fluent with preserved comprehension. The right arm weakness indicates involvement of adjacent motor cortex, localizing to left frontal lobe.
- A 70-year-old man has sudden onset of dense right hemiplegia affecting the face, arm, and leg equally. Reflexes are brisk on the right with a Babinski sign. Where is the lesion? Left internal capsule. The internal capsule contains tightly packed corticospinal and corticobulbar fibers, so a lesion causes dense contralateral hemiplegia affecting face, arm, and leg equally.
- A patient has difficulty with coordination in the right arm and leg, with past-pointing and intention tremor when reaching. Where is the most likely lesion? Right cerebellar hemisphere. The cerebellum controls coordination ipsilaterally. A lesion in the right cerebellar hemisphere causes right-sided limb ataxia.
- A patient has a wide-based unsteady gait, falls frequently, and has nystagmus. Limb coordination is relatively normal. Where is the lesion? Cerebellar vermis. The vermis is responsible for axial and truncal coordination. Damage causes gait ataxia and nystagmus, with relative sparing of limb coordination.
- A patient has bilateral loss of pain and temperature sensation below the level of the umbilicus, but fine touch and proprioception are intact. Where is the lesion? Bilateral spinothalamic tracts. Pain and temperature fibers ascend in the spinothalamic tracts. Bilateral damage to these tracts causes loss of these modalities below the lesion with preserved dorsal column functions.
- A patient has loss of proprioception and vibration in the right leg, and loss of pain and temperature in the left leg. Where is the lesion? Right half of the spinal cord. Brown-Sequard syndrome results from hemisection of the spinal cord: ipsilateral loss of proprioception/vibration and contralateral loss of pain/temperature.
- A patient has a right homonymous hemianopia with macular sparing. Where is the most likely lesion? Left occipital cortex. Occipital cortex lesions cause contralateral homonymous hemianopia, and macular sparing is common due to dual blood supply to the macula.
- A patient has difficulty performing learned motor tasks such as using a comb or brushing teeth, despite having normal strength and coordination. Where is the lesion? Left parietal cortex. Apraxia, the inability to perform learned movements despite intact motor function, is typically caused by damage to the left parietal cortex.
- A patient has profound anterograde amnesia, unable to form new memories, but can recall events from years ago. Where is the most likely lesion? Bilateral hippocampus. The hippocampus is critical for converting short-term to long-term memory. Bilateral damage results in inability to form new memories.
- A patient has a left third nerve palsy (ptosis, dilated pupil, eye deviated down and out) and right hemiplegia. Where is the lesion? Left midbrain. Weber syndrome localizes to the midbrain, where the oculomotor nerve and cerebral peduncle are adjacent. A lesion affects both.
- A patient has loss of pain and temperature on the left side of the face, and loss of pain and temperature on the right side of the body, along with ataxia and a left Horner's syndrome. Where is the lesion? Left lateral medulla. Lateral medullary syndrome (Wallenberg) results from a lesion in the lateral medulla, affecting the spinal trigeminal nucleus, spinothalamic tract, and sympathetic fibers.
- A patient has a resting tremor, bradykinesia, and rigidity, predominantly on the right side. Where is the most likely lesion? Left substantia nigra. The nigrostriatal pathway is ipsilateral. Loss of dopamine in the left substantia nigra leads to disinhibition of the indirect pathway, causing contralateral (right-sided) parkinsonism.
- A patient has sudden onset of flaccid paralysis of both legs, loss of pain and temperature below the level of the lesion, but preservation of proprioception and vibration. Where is the lesion? Anterior spinal artery territory of the spinal cord. The anterior spinal artery supplies the anterior two-thirds of the cord, including corticospinal and spinothalamic tracts, but not dorsal columns, causing this pattern.
See it in 3D: open the interactive brain and click any region, or ask the AI coach anything you missed.