微小血管減圧術が有効であった舌咽神経痛の1例

Microvascular Decompression for Glossopharyngeal Neuralgia : Case Report

Ⅰ．は じ め に

　舌咽神経痛は比較的稀な疾患であり，同様の性質をもつ三叉神経痛の1/70の頻度でみられると言われている¹⁾．しかし，稀ではあるが舌咽神経支配領域（咽頭，舌，耳など）に発作性・短時間性・穿刺性・片側性の痛みを伴い，日常生活に支障を来している場合が少なくない．

　舌咽神経痛の発作の発現機序はいまだ完全に解明されていないが，脳幹への神経根侵入部の軸索に動脈の圧迫⁸⁾や拍動が持続的に加わり，脱髄性変化¹³⁾が起こって異所性脱分極が生じ，疼痛を形成するといわれている．

　舌咽神経痛を認めた場合の治療は，通常カルバマゼピン等の内科的治療が行われるが，内服治療が無効，もしくは副作用にて継続困難な場合，外科的治療が考慮される．現在，外科的治療の第一選択として微小血管減圧術が行われているが，無効例や長期経過中の再発例が存在することも知られている．

　今回われわれは，微小血管減圧術が有効であった舌咽神経痛の1例を経験した．その症例を通し，無効例および再発例の原因について文献的考察を加え報告する．

We report the case of a glossopharyngeal neuralgia that was successfully treated using microvascular decompression (MVD).

　A 61-year-old female reported intermittent piercing pain from tongue to pinna on the left side. Although she had been prescribed carbamazepine and has undergone attempted nerve block on several occasions,no pain relief has been achieved. MVD was thus attempted using a lateral suboccipital approach. The offending vessel,which was PICA,had adhered to the glossopharyngeal nerve and was repositioned laterally away from the nerve by interposition of a felt cushion. Pain disappeared immediately after surgery and has not recurred.

　In the literature,MVD for glossopharyngeal neuralgia has been performed using a transcondylar approach to achieve minimally invasive surgery. However,the sensory distributions for the floor of the oral cavity and tongue involve 4 overlapping nerves : the trigeminal nerve,sensory components of the facial and vagal nerves,and the glossopharyngeal nerve. In typical cases,it seems that the transcondylar fossa approach is appropriate for glossopharyngeal neuralgia. If the pain occurs in the place involving an overlapping nerve,the lateral suboccipital approach might be necessary.