A patient has presented to hospital with anorexia-like symptoms (very lean, loss of appetite, almost no adipose tissue). An MRI scan of the patient’s brain has found that a region of the hypothalamus has been lesioned by a tumour. Which nucleus or nuclei could it be?
一位患者因出现类似厌食症的症状（极度消瘦、食欲不振、几乎没有脂肪组织）入院。患者的脑部核磁共振扫描发现，下丘脑的某个区域被肿瘤侵犯。请问可能是哪个或哪些核团？

Question

BlackTom AI · Accepted Answer

Lateral hypothalamus (LH) is the classic “feeding center,” so a lesion there produces aphagia, anorexia and profound weight loss.

1) Relevant knowledge points and concepts
- The hypothalamus contains specialized nuclei that regulate feeding: the lateral hypothalamus (LH) promotes feeding (hunger center); the ventromedial hypothalamus (VMH) promotes satiety (satiety center).  
- LH neurons (including orexin/hypocretin and MCH cells) drive appetite and motivated food-seeking; lesioning LH abolishes those drives.  
- VMH lesions classically produce hyperphagia and obesity.  
- The arcuate nucleus contains both orexigenic (NPY/AgRP) and anorexigenic (POMC/CART) populations and integrates peripheral signals (leptin, ghrelin); damage here gives more complex neuroendocrine effects.  
- The median eminence is a neurovascular interface for hypothalamic releasing hormones to the pituitary and is not the primary feeding center.

2) Step-by-step reasoning
- Patient phenotype: severe leanness, loss of appetite, almost no adipose tissue → indicates markedly reduced food intake (aphagia/anorexia), long-term negative energy balance.  
- Which nucleus produces that phenotype when lesioned? LH lesions remove the brain’s hunger drive → loss of appetite and weight loss. Therefore LH damage matches the symptoms.  
- Test alternatives against the phenotype:
  - VMH lesion would give the opposite picture (overeating and obesity), so VMH is inconsistent.  
  - Arcuate nucleus lesion can disrupt feeding regulation but typically causes mixed endocrine and reproductive disturbances; complete arcuate destruction is not the classic cause of pronounced aphagia as seen with LH lesions.  
  - Median eminence lesions produce pituitary hormonal dysregulation, not a primary aphagia/near-total loss of adipose tissue presentation.

3) Why the correct answer is correct
Lesioning the LH removes orexigenic drive and motivational systems for eating, producing profound anorexia and weight loss—exactly the patient’s presentation.

4) Why other options are incorrect
- Median eminence: mainly pituitary portal interface, not primary hunger center.  
- VMH: lesion → hyperphagia/obesity (opposite).  
- Arcuate nucleus: complex integrator; lesions do not classically cause the dramatic aphagia described.

Conclusion: The correct nucleus is the Lateral Hypothalamus, matching the provided answer.

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