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1 BIOLOGY MCQS

Locked-in syndrome (LiS) is which type of disorder?

  • Developmental
  • Neurological
  • Hormonic
  • Genetic
Correct Answer: B. Neurological

Detailed Explanation

Locked-in syndrome (LiS) is a rare neurological disorder that results from damage to specific areas of the brainstem, particularly the pons, which controls voluntary muscle movements. This condition causes complete paralysis of almost all voluntary muscles, except for the eyes and eyelids, leaving the person fully conscious but unable to move or speak.  Causes of Locked-in Syndrome:




  • Stroke: Most common cause, particularly a brainstem stroke that interrupts communication between the brain and spinal cord.




  • Traumatic brain injury.




  • Diseases that destroy nerve cells, such as amyotrophic lateral sclerosis (ALS).




  • Infections or tumors in the brainstem region.




Characteristics of LiS:




  • The person is awake and fully aware of their surroundings.




  • They cannot speak, chew, swallow, or move limbs voluntarily.




  • Communication is usually possible only through eye movements or blinking, which remain intact because they are controlled by different neural pathways.




  • Cognitive abilities (thinking, memory, reasoning) are completely preserved.




Why the Correct Answer is “Neurological”:




  • LiS directly involves damage to the nervous system, specifically affecting the transmission of motor commands from the brain to the body.




  • It is not a developmental disorder, as it does not occur due to abnormal growth during childhood.




  • It is not hormonal, since it is unrelated to hormonal imbalances.




  • It is not purely genetic, though some genetic conditions may increase the risk of brainstem injury or neurodegeneration.




Treatment is mainly supportive, with rehabilitation, physical therapy, and advanced communication devices helping patients improve quality of life, but full recovery is rare.


✅ Correct Answer: Neurological disorder.

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