Motor Control - Clinical Case Flashcards
A 57-year-old right-handed policeman presents complaining of tiredness, weakness in the limbs, loss of weight, breathlessness, slurred speech and difficulty swallowing.
He had first noticed tiredness when walking one year ago. He used to walk easily several miles when on the beat, but now he had to rest every couple of miles. The legs felt stiff. In addition, he appeared to drag the feet and tripped easily. He had frequent cramps in his calves. He also had developed difficulty carrying things like a cup of coffee and lifting his arms in activities such as combing his hair or reaching for objects in high cupboards. In the last 12 months he had lost two stone in weight, but his appetite was normal. From the onset of the condition he had noted slurring of his speech, but in the last 6 months it had deteriorated markedly, to the extent that it was difficult for people to understand what he said. He had difficulty swallowing. It took a long time for him to negotiate a meal; the food had to be cut in small pieces or liquidized. If he was not careful fluids could go “the wrong way” and triggered bouts of cough. His memory was good and the function of his sphincters normal.
He had been previously healthy, did not drink alcohol and there was no family history of neurological disease. His two sons aged 30 and 25 were healthy.
On examination he looked thin. His weight was 66 kg for a height of 1.85m (6 feet). He was fully alert and co-operative. The gait was abnormal with spasticity and bilateral foot drop. He used a stick. His speech was slurred and difficult to understand, but the words used were grammatically correct. The tongue was wasted bilaterally, protruded to just outside the lips and moved very slowly. He had difficulty in drinking water: it was slow, required double swallow per mouthful and it triggered cough. Fasciculations were seen in the tongue. His palate elevated poorly with phonation, but the gag reflex was pathologically brisk. The jaw jerk was increased. He had wasting of the shoulders; arms, forearms and legs (both anterior tibial compartments and calves), this was more marked on the right than on the left in the arms and vice-versa in the legs. There were widespread fasciculations in the arms, forearms, thighs and legs. He had increased tone (spasticity) in the upper and lower limbs. He had weakness in all muscle groups in the arms (right more than left, and more marked proximally), and in the legs (left more than right and more marked distally). All deep tendon reflexes in the arms and legs were pathologically brisk. The plantar responses were extensor and abdominal reflexes were absent. All sensory modalities were preserved.
What anatomical part (or parts) of the nervous system is (are) affected?
- Both upper motor neurons (UMN) and lower motor neurons (LMN) are affected.
A 57-year-old right-handed policeman presents complaining of tiredness, weakness in the limbs, loss of weight, breathlessness, slurred speech and difficulty swallowing.
He had first noticed tiredness when walking one year ago. He used to walk easily several miles when on the beat, but now he had to rest every couple of miles. The legs felt stiff. In addition, he appeared to drag the feet and tripped easily. He had frequent cramps in his calves. He also had developed difficulty carrying things like a cup of coffee and lifting his arms in activities such as combing his hair or reaching for objects in high cupboards. In the last 12 months he had lost two stone in weight, but his appetite was normal. From the onset of the condition he had noted slurring of his speech, but in the last 6 months it had deteriorated markedly, to the extent that it was difficult for people to understand what he said. He had difficulty swallowing. It took a long time for him to negotiate a meal; the food had to be cut in small pieces or liquidized. If he was not careful fluids could go “the wrong way” and triggered bouts of cough. His memory was good and the function of his sphincters normal.
He had been previously healthy, did not drink alcohol and there was no family history of neurological disease. His two sons aged 30 and 25 were healthy.
On examination he looked thin. His weight was 66 kg for a height of 1.85m (6 feet). He was fully alert and co-operative. The gait was abnormal with spasticity and bilateral foot drop. He used a stick. His speech was slurred and difficult to understand, but the words used were grammatically correct. The tongue was wasted bilaterally, protruded to just outside the lips and moved very slowly. He had difficulty in drinking water: it was slow, required double swallow per mouthful and it triggered cough. Fasciculations were seen in the tongue. His palate elevated poorly with phonation, but the gag reflex was pathologically brisk. The jaw jerk was increased. He had wasting of the shoulders; arms, forearms and legs (both anterior tibial compartments and calves), this was more marked on the right than on the left in the arms and vice-versa in the legs. There were widespread fasciculations in the arms, forearms, thighs and legs. He had increased tone (spasticity) in the upper and lower limbs. He had weakness in all muscle groups in the arms (right more than left, and more marked proximally), and in the legs (left more than right and more marked distally). All deep tendon reflexes in the arms and legs were pathologically brisk. The plantar responses were extensor and abdominal reflexes were absent. All sensory modalities were preserved.
What symptoms and signs indicate involvement of what part (parts) of the nervous system?
UMN:
* “stiff”
* “cramps”
* “spasticity”
* “gag reflex was pathologically brisk”
* “jaw jerk was increased”
* “increased tone (spasticity)”
* “deep tendon reflexes in the arms and legs were pathologically brisk”
* “plantar responses were extensor and abdominal reflexes were absent”
LMN:
* “tongue was wasted bilaterally”
* “Fasciculations”
* “palate elevated poorly with phonation”
* “wasting of the shoulders”
* “widespread fasciculations in the arms, forearms, thighs and legs”
Combination of both:
* “tiredness, weakness in the limbs, loss of weight, breathlessness, slurred speech and difficulty swallowing”
* “difficulty carrying things like a cup of coffee and lifting his arms in activities such as combing his hair or reaching for objects in high cupboards”
* “slurring of his speech”
* “go “the wrong way” and triggered bouts of cough”
* “bilateral foot drop”
* “protruded to just outside the lips and moved very slowly”
* “weakness in all muscle groups in the arms”
A 57-year-old right-handed policeman presents complaining of tiredness, weakness in the limbs, loss of weight, breathlessness, slurred speech and difficulty swallowing.
He had first noticed tiredness when walking one year ago. He used to walk easily several miles when on the beat, but now he had to rest every couple of miles. The legs felt stiff. In addition, he appeared to drag the feet and tripped easily. He had frequent cramps in his calves. He also had developed difficulty carrying things like a cup of coffee and lifting his arms in activities such as combing his hair or reaching for objects in high cupboards. In the last 12 months he had lost two stone in weight, but his appetite was normal. From the onset of the condition he had noted slurring of his speech, but in the last 6 months it had deteriorated markedly, to the extent that it was difficult for people to understand what he said. He had difficulty swallowing. It took a long time for him to negotiate a meal; the food had to be cut in small pieces or liquidized. If he was not careful fluids could go “the wrong way” and triggered bouts of cough. His memory was good and the function of his sphincters normal.
He had been previously healthy, did not drink alcohol and there was no family history of neurological disease. His two sons aged 30 and 25 were healthy.
On examination he looked thin. His weight was 66 kg for a height of 1.85m (6 feet). He was fully alert and co-operative. The gait was abnormal with spasticity and bilateral foot drop. He used a stick. His speech was slurred and difficult to understand, but the words used were grammatically correct. The tongue was wasted bilaterally, protruded to just outside the lips and moved very slowly. He had difficulty in drinking water: it was slow, required double swallow per mouthful and it triggered cough. Fasciculations were seen in the tongue. His palate elevated poorly with phonation, but the gag reflex was pathologically brisk. The jaw jerk was increased. He had wasting of the shoulders; arms, forearms and legs (both anterior tibial compartments and calves), this was more marked on the right than on the left in the arms and vice-versa in the legs. There were widespread fasciculations in the arms, forearms, thighs and legs. He had increased tone (spasticity) in the upper and lower limbs. He had weakness in all muscle groups in the arms (right more than left, and more marked proximally), and in the legs (left more than right and more marked distally). All deep tendon reflexes in the arms and legs were pathologically brisk. The plantar responses were extensor and abdominal reflexes were absent. All sensory modalities were preserved.
What pathways are affected?
- Pyramidal tracts (these are the corticospinal and corticobulbar tracts) providing voluntary motor commands to limbs / trunk and head / neck respectively
A 57-year-old right-handed policeman presents complaining of tiredness, weakness in the limbs, loss of weight, breathlessness, slurred speech and difficulty swallowing.
He had first noticed tiredness when walking one year ago. He used to walk easily several miles when on the beat, but now he had to rest every couple of miles. The legs felt stiff. In addition, he appeared to drag the feet and tripped easily. He had frequent cramps in his calves. He also had developed difficulty carrying things like a cup of coffee and lifting his arms in activities such as combing his hair or reaching for objects in high cupboards. In the last 12 months he had lost two stone in weight, but his appetite was normal. From the onset of the condition he had noted slurring of his speech, but in the last 6 months it had deteriorated markedly, to the extent that it was difficult for people to understand what he said. He had difficulty swallowing. It took a long time for him to negotiate a meal; the food had to be cut in small pieces or liquidized. If he was not careful fluids could go “the wrong way” and triggered bouts of cough. His memory was good and the function of his sphincters normal.
He had been previously healthy, did not drink alcohol and there was no family history of neurological disease. His two sons aged 30 and 25 were healthy.
On examination he looked thin. His weight was 66 kg for a height of 1.85m (6 feet). He was fully alert and co-operative. The gait was abnormal with spasticity and bilateral foot drop. He used a stick. His speech was slurred and difficult to understand, but the words used were grammatically correct. The tongue was wasted bilaterally, protruded to just outside the lips and moved very slowly. He had difficulty in drinking water: it was slow, required double swallow per mouthful and it triggered cough. Fasciculations were seen in the tongue. His palate elevated poorly with phonation, but the gag reflex was pathologically brisk. The jaw jerk was increased. He had wasting of the shoulders; arms, forearms and legs (both anterior tibial compartments and calves), this was more marked on the right than on the left in the arms and vice-versa in the legs. There were widespread fasciculations in the arms, forearms, thighs and legs. He had increased tone (spasticity) in the upper and lower limbs. He had weakness in all muscle groups in the arms (right more than left, and more marked proximally), and in the legs (left more than right and more marked distally). All deep tendon reflexes in the arms and legs were pathologically brisk. The plantar responses were extensor and abdominal reflexes were absent. All sensory modalities were preserved.
Why are the abdominal reflexes absent while the other reflexes are brisk?
- This is the hallmark of a pure corticospinal tract lesion
Stroking the skin of the abdomen causes the abdominal wall muscles to contract, sometimes pulling theumbilicustowards the stimulus. These reflexcontractions are often absent inupper motor neurone disorders.
A 57-year-old right-handed policeman presents complaining of tiredness, weakness in the limbs, loss of weight, breathlessness, slurred speech and difficulty swallowing.
He had first noticed tiredness when walking one year ago. He used to walk easily several miles when on the beat, but now he had to rest every couple of miles. The legs felt stiff. In addition, he appeared to drag the feet and tripped easily. He had frequent cramps in his calves. He also had developed difficulty carrying things like a cup of coffee and lifting his arms in activities such as combing his hair or reaching for objects in high cupboards. In the last 12 months he had lost two stone in weight, but his appetite was normal. From the onset of the condition he had noted slurring of his speech, but in the last 6 months it had deteriorated markedly, to the extent that it was difficult for people to understand what he said. He had difficulty swallowing. It took a long time for him to negotiate a meal; the food had to be cut in small pieces or liquidized. If he was not careful fluids could go “the wrong way” and triggered bouts of cough. His memory was good and the function of his sphincters normal.
He had been previously healthy, did not drink alcohol and there was no family history of neurological disease. His two sons aged 30 and 25 were healthy.
On examination he looked thin. His weight was 66 kg for a height of 1.85m (6 feet). He was fully alert and co-operative. The gait was abnormal with spasticity and bilateral foot drop. He used a stick. His speech was slurred and difficult to understand, but the words used were grammatically correct. The tongue was wasted bilaterally, protruded to just outside the lips and moved very slowly. He had difficulty in drinking water: it was slow, required double swallow per mouthful and it triggered cough. Fasciculations were seen in the tongue. His palate elevated poorly with phonation, but the gag reflex was pathologically brisk. The jaw jerk was increased. He had wasting of the shoulders; arms, forearms and legs (both anterior tibial compartments and calves), this was more marked on the right than on the left in the arms and vice-versa in the legs. There were widespread fasciculations in the arms, forearms, thighs and legs. He had increased tone (spasticity) in the upper and lower limbs. He had weakness in all muscle groups in the arms (right more than left, and more marked proximally), and in the legs (left more than right and more marked distally). All deep tendon reflexes in the arms and legs were pathologically brisk. The plantar responses were extensor and abdominal reflexes were absent. All sensory modalities were preserved.
What is a fasciculation? What is its significance?
- Fasciculation: involuntary and abnormal firing of a single motor neuron and all its innervated muscle fibres, leading to twitching visible to the eye
- Significance: LMN damage
A 57-year-old right-handed policeman presents complaining of tiredness, weakness in the limbs, loss of weight, breathlessness, slurred speech and difficulty swallowing.
He had first noticed tiredness when walking one year ago. He used to walk easily several miles when on the beat, but now he had to rest every couple of miles. The legs felt stiff. In addition, he appeared to drag the feet and tripped easily. He had frequent cramps in his calves. He also had developed difficulty carrying things like a cup of coffee and lifting his arms in activities such as combing his hair or reaching for objects in high cupboards. In the last 12 months he had lost two stone in weight, but his appetite was normal. From the onset of the condition he had noted slurring of his speech, but in the last 6 months it had deteriorated markedly, to the extent that it was difficult for people to understand what he said. He had difficulty swallowing. It took a long time for him to negotiate a meal; the food had to be cut in small pieces or liquidized. If he was not careful fluids could go “the wrong way” and triggered bouts of cough. His memory was good and the function of his sphincters normal.
He had been previously healthy, did not drink alcohol and there was no family history of neurological disease. His two sons aged 30 and 25 were healthy.
On examination he looked thin. His weight was 66 kg for a height of 1.85m (6 feet). He was fully alert and co-operative. The gait was abnormal with spasticity and bilateral foot drop. He used a stick. His speech was slurred and difficult to understand, but the words used were grammatically correct. The tongue was wasted bilaterally, protruded to just outside the lips and moved very slowly. He had difficulty in drinking water: it was slow, required double swallow per mouthful and it triggered cough. Fasciculations were seen in the tongue. His palate elevated poorly with phonation, but the gag reflex was pathologically brisk. The jaw jerk was increased. He had wasting of the shoulders; arms, forearms and legs (both anterior tibial compartments and calves), this was more marked on the right than on the left in the arms and vice-versa in the legs. There were widespread fasciculations in the arms, forearms, thighs and legs. He had increased tone (spasticity) in the upper and lower limbs. He had weakness in all muscle groups in the arms (right more than left, and more marked proximally), and in the legs (left more than right and more marked distally). All deep tendon reflexes in the arms and legs were pathologically brisk. The plantar responses were extensor and abdominal reflexes were absent. All sensory modalities were preserved.
How would you summarise the abnormalities in the structure and function of motor units exemplified by this case history?
- This is a case of motor neurone disease (also called Amyotrophic Lateral Sclerosis).
- This case is about denervation & reinnervation.
This can be demonstrated by miming two motor units side by side in a muscle with your arms:
Hold up both your hands - they are two motor neurones. Spread out your fingers - they are the lower motor neurone axon sprouts. Each axon sprout innervates several muscle fibres (the motor axon and all the muscle fibres it innervates is the motor unit). Cortical command comes down the motor neurones and causes the muscle fibres to contract in a coordinated fashion. One day something happens and one of the motor neurones dies - put one hand down. The muscle fibres of that motor unit lose their nerve supply – they are denervated. So, the axons of the remaining motor unit grow and reach out to the denervated muscles fibres – reinnervation takes place. The resulting new motor unit is larger and less stable and prone to ectopic generation of electrical stimuli in the distal axon that cause contraction of the muscle fibres. A fasciculation.
