頚椎症の診断で紹介されたVB12欠乏性亜急性連合性脊髄変性症の1例

A Case of Subacute Combined Degeneration Caused by Vitamin B12 Deficiency in a Cervical Spondylosis Surgery Referral

Ⅰ．はじめに

　頚椎症は頚椎椎間板，Luschka関節，椎間関節などに生じた加齢変化が原因で，椎間板膨隆，靱帯の肥厚，骨棘形成が起こった状態をいい，中高年の手のしびれや歩行障害を来す脊髄疾患全体の中で最も頻度の高い病態である²⁾．脊椎の専門外来には，近医より紹介され外科的処置を希望する患者が日々数多く来院する．しかしながら，来院する患者の中には，詳細な病歴聴取や神経学的診察を怠ると，思わぬpitfallに陥るケースが存在する．今回われわれは，頚椎症性脊髄症との診断で手術目的に近医整形外科より紹介されたVB₁₂欠乏性亜急性連合性脊髄変性症の1例を経験したため報告する．

　A 62-year-old man with a 1-year history of numbness of the extremities, clumsiness, and gait disorder was diagnosed with cervical spondylotic myelopathy at a neighboring clinic and referred to our institution for surgery. The patient had undergone a total gastrectomy 6 years previously. Flattening of the cervical cord, associated with diffuse cervical spondylosis and intramedullary intensity change, was observed on magnetic resonance imaging of the cervical spine. Neurological examination revealed decreased vibratory and position sense in all limbs, with posterior funiculus-based neurological symptoms. Blood biochemistry revealed decreased vitamin B₁₂（VB₁₂）levels and megaloblastic anemia. On the basis of these findings, the patient was diagnosed with subacute combined degeneration（SCD). The patient was treated with VB₁₂ for 3 months；the gait disorder resolved and the intramedullary intensity changes in the posterior column of the medulla oblongata, thoracicus, and spinal cord were no longer observed. SCD is a pathological condition in which recovery of neurological function may be achieved through early administration of VB₁₂. In some cases, it is difficult to differentiate between this condition and cervical spondylotic myelopathy because both diseases exhibit progressive spinal symptoms. The medical history and results of neurological evaluations of the patient are important for an accurate diagnosis, and should therefore not be overlooked.