For each case of neurological abnormality due to damage in the nervous system A–E, select the most appropriate option for the site of that damage from the following list of sites for the damaged area (lesion).
1. Lower motor neurones (peripheral).
2. Upper motor neurones (central).
3. Left cerebral hemisphere.
4. Right cerebral hemisphere.
5. Left half of spinal cord.
6. Right half of spinal cord.
- A 40-year-old man has noticed that his right leg feels ‘different’, but he has not noticed any weakness. On testing, his right leg is not as good as the left at detecting a pin-prick or a cold metallic object.
- An 80-year-old woman is found to have moderate weakness on one side of her body. She seems fairly aware of her surroundings but appears not to be able to speak.
- A 20-year-old man was involved in a motor bike crash a month ago. He has weakness and clumsiness in his right arm but there is no abnormality of feeling. The thenar emi-nence on the right is flatter than that on the left. The biceps reflex on the right is
- A 70-year-old woman developed weakness in her right arm and leg a month ago and was admitted to hospital. The weakness is still present in her right arm and sensation is not as good as in the left. The biceps reflex on the right is stronger than that on t
- A 30-year-old man in a wheelchair has severe weakness of both legs. The leg reflexes are brisker than normal.
Medicine
A. Option 5 Left half of spinal cord. This man has impaired pain and temperature sensation in his right leg. These sensory modalities are conveyed in pathways which cross the mid line soon after entry to the spinal cord, so the lesion is in the left side, affecting the spino-thalamic tract.
B. Option 3 Left cerebral hemisphere. The age and symptoms are typical of a ‘stroke’. We are not told the side of the weakness, but since the left cerebral hemisphere is concerned with speech in the great majority of people, the lesion is most likely to be in the left than the right hemisphere.
C. Option 1 Lower motor neurones. Weakness without sensory loss suggests a motor abnormality. Wasting and impaired reflexes are typical of a lower motor neurone lesion.
D. Option 3 Left cerebral hemisphere. Persisting weakness of an upper motor neurone type (brisk reflex), together with loss of sensation suggest the effects of a stroke affecting the brain on the opposite side.
E. Option 2 Upper motor neurones. This man has bilateral upper motor neurone weakness of the legs with typically increased reflexes. A common cause would be a spinal cord injury, in which case further testing should show serious sensory loss on both sides.
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