Questions:
A patient has entered your clinic with the following symptoms:
1. Decreased to absent reflexes in both lower limbs
2. paralysis/paresis (flaccid) in both lower limbs
3. Rapid, severe atrophy of the muscles in the lower limbs
What is causing these symptoms and what is the physiological reason for each of these symptoms?
Describe an injury that may cause these symptoms.
Define the terms hyporeflexia, areflexia, flaccid paralysis, and neurogenic atrophy.
Would any autonomic function be disrupted in this scenario? Why or why not?
Answers:
A. What is causing these symptoms and what is the physiological reason for each of these symptoms?
1. Decreased to absent reflexes in both lower limbs are symptoms of a peripheral nerve injury, thrombophlebitis, spinal shock or any injury which occurs below T1. A reflex muscle contraction occurs by the activation of a nerve in a specific area from the legs to the spinal cord. Damage to the nerve along this area will interfere with muscle contraction.
2. Paralysis/paresis (flaccid) in both lower limbs can be caused by any damage or interruption of lower motor neurons, because this damage affects nerve fibers traveling from the anterior horn of the spinal cord to the relevant muscle(s). It can also be caused by cauda equine syndrome and any injury at or below the anterior horn cell.
3. Rapid, severe atrophy of the muscles in the lower limbs are caused by malformations or malfunctions of the central nervous system and lower motor neurons. It occurs when there is an injury to, or disease of a nerve such as Amyotrophic Lateral Sclerosis.
B. Describe an injury that may cause these symptoms.
1. Decreased to absent reflexes in both lower limbs are caused by an injury to the central nervous system. It can be brought on by damage to the nerves that run through the spinal cord and branch out to the extremities. This damage often takes the form of a pinched nerve caused by something pressing against the nerve and disturbing its normal functioning.
2. Paralysis/paresis (flaccid) in both lower limbs results from an injury to motor cells in the brainstem or spinal cord, or of the axons derived from them; this injury affects nerve fibers traveling from the anterior horn of the spinal cord to the relevant muscle(s). It also can be caused by an injury to nerves within the spinal cord as they exit the lumbar and sacral regions, which usually result from a fracture below L2. Cauda equina syndrome causes flaccid paralysis because the injury occurs at the lumbosacral nerve roots in the spinal canal. These nerves lead to the lower limbs.
3. The most common causes of severe muscle atrophy in the lower limb are lower motor neuron injuries which cause traumas to peripheral nerves. When a body part is affected by paralysis, the muscles may atrophy through lack of use. Muscle atrophy also results if nerve cells (neurons) waste away or die, and are no longer able to send messages to muscles. This eventually leads to an inability to move the legs, and body, muscle weakening and muscle atrophy due to lack of use. .
C. Define the terms hyporeflexia, areflexia, flaccid paralysis, and neurogenic atrophy.
a. The definition of Hyporeflexia is an absent or diminished response to tapping. It usually indicates a disease that involves one or more the components of the two-neuron reflex arc itself.
b. The definition of Areflexia is absence of reflexes. It is decreased tendon reflex that is indicative of a breach in any part of the reflex motor arc. It may involve:
o the muscle - myopathy
o the nerve endings - polyneuritis
o the motor nerve - neuropathy
o the anterior spinal cord root, e.g. spondylosis
o the anterior horn cell, e.g. motor neurone disease, poliomyelitis
o the sensory arc sensory root or sensory nerve disease
o systemic disease, e.g. abetalipoproteinaemia
c. The definition of flaccid paralysis is weakness or loss of muscle tone resulting from injury or disease of the nerves innervating the muscles. The muscles are limp and cannot contract.
d. The definition of neurogenic atrophy is muscle wasting due to damage to its peripheral nerve supply.
D. Would any autonomic function be disrupted in this scenario? Why or why not?
Autonomic functions would be disrupted by flaccid paralysis and hyporeflexia. During an injury, the spinal column and the spinal cord can be injured anywhere along their length. In a spinal cord injury, spinal shock occurs, which results in a complete loss of all motor, sensory, reflex, and autonomic function below the level of the injury. This loss is evidenced by peripheral vascular tone, which results in flaccid paralysis. Spinal shocks can recover by complication of autonomic hyperreflexia if the spinal cord injury occurred above T6.
o the muscle - myopathy
o the nerve endings - polyneuritis
o the motor nerve - neuropathy
o the anterior spinal cord root, e.g. spondylosis
o the anterior horn cell, e.g. motor neurone disease, poliomyelitis
o the sensory arc sensory root or sensory nerve disease
o systemic disease, e.g. abetalipoproteinaemia
c. The definition of flaccid paralysis is weakness or loss of muscle tone resulting from injury or disease of the nerves innervating the muscles. The muscles are limp and cannot contract.
d. The definition of neurogenic atrophy is muscle wasting due to damage to its peripheral nerve supply.
D. Would any autonomic function be disrupted in this scenario? Why or why not?
Autonomic functions would be disrupted by flaccid paralysis and hyporeflexia. During an injury, the spinal column and the spinal cord can be injured anywhere along their length. In a spinal cord injury, spinal shock occurs, which results in a complete loss of all motor, sensory, reflex, and autonomic function below the level of the injury. This loss is evidenced by peripheral vascular tone, which results in flaccid paralysis. Spinal shocks can recover by complication of autonomic hyperreflexia if the spinal cord injury occurred above T6.
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