Berkowitz Neuroanatomy Chapter 8 Quiz

Which cerebellar lesion is most likely to result in truncal ataxia without limb ataxia?

• Lesion of the lateral hemispheres

• Lesion of the vermis

• Lesion of the dentate nucleus

• Lesion of the flocculonodular lobe

Answer explanation

The vermis controls the coordination of the trunk. Lesions in this area typically result in truncal ataxia without affecting limb coordination.

Damage to which structure within the cerebellum is most closely associated with intention tremor?

• Vermis

• Dentate Nucleus

• Flocculonodular lobe

• Fastigial nucleus

Answer explanation

The dentate nucleus is one of the deep cerebellar nuclei and plays a crucial role in the coordination of voluntary movements. Damage to this structure results in intention tremor, which is characterized by a tremor that occurs or worsens during voluntary movements, such as reaching for an object.

Which of the following is a distinguishing feature of spinocerebellar ataxia compared to other forms of ataxia?

• Pure sensory ataxia

• Progressive limb ataxia with genetic inheritance

• Sudden onset of ataxia with vertigo

• Ataxia limited to gait instability

Answer explanation

Spinocerebellar ataxia (SCA) refers to a group of hereditary ataxias characterized by progressive incoordination of gait and often limb movements, due to cerebellar degeneration. The genetic basis and progressive nature of SCA distinguish it from other forms of ataxia, which may not be inherited or progressively worsening.

What is the most likely location of a cerebellar infarction that causes isolated dysarthria without other cerebellar signs?

• Vermis

• Right cerebellar hemisphere

• Left cerebellar hemisphere

• Flocculonodular lobe

Answer explanation

The vermis is involved in the coordination of speech and axial movements. An infarction in this area can cause isolated dysarthria, which is difficulty in articulating speech, without affecting limb coordination. Dysarthria due to vermis damage manifests as slurred or slow speech.

In a patient with suspected cerebellar ataxia, which clinical test and its outcome would most reliably differentiate cerebellar ataxia from other types of ataxia, and why?

• Heel-to-shin test showing dysmetria

• Romberg test positive with eyes open

• Finger-to-nose test demonstrating past pointing

• Tandem gait test showing increased unsteadiness

Answer explanation

The Romberg test is used to differentiate between sensory and cerebellar ataxia. A positive Romberg test (increased unsteadiness) with the patient's eyes open suggests cerebellar ataxia, as the cerebellum is responsible for integrating sensory input and motor coordination to maintain balance. Sensory ataxia, caused by impaired proprioception, typically results in a positive Romberg test only when the patient's eyes are closed. Therefore, a positive Romberg test with eyes open is a more specific indicator of cerebellar dysfunction. Dysmetria on the heel-to-shin test and past pointing on the finger-to-nose test can occur with both cerebellar and sensory ataxia, while increased unsteadiness on the tandem gait test is not specific enough to differentiate between these types of ataxia.

In a patient presenting with acute myelopathy, which of the following findings would most strongly suggest a diagnosis of anterior spinal artery syndrome, and why?

• Bilateral loss of vibration and proprioception with preserved pain and temperature sensation.

• Unilateral motor weakness with contralateral sensory loss.

• Bilateral motor paralysis and loss of pain and temperature sensation with preserved vibration and proprioception.

• Progressive muscle atrophy and fasciculations without sensory loss.

Answer explanation

Anterior spinal artery syndrome results from ischemia to the anterior portion of the spinal cord, which supplies the anterior two-thirds of the spinal cord. This syndrome typically presents with bilateral motor paralysis due to involvement of the corticospinal tracts and loss of pain and temperature sensation due to involvement of the spinothalamic tracts. The dorsal columns, which carry vibration and proprioception, are often spared because they are supplied by the posterior spinal arteries. This clinical pattern of deficits helps differentiate anterior spinal artery syndrome from other types of spinal cord lesions.