Horita Masahiro, Saiga Kenta, Fujiwara Tomohiro, Nakata Eiji, Ozaki Toshifumi
Department of Orthopaedic Surgery, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan.
Department of Sports Medicine, Faculty of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Japan.
Foot Ankle Orthop. 2024 Aug 26;9(3):24730114241268285. doi: 10.1177/24730114241268285. eCollection 2024 Jul.
Morton neuroma is a common cause of forefoot pain and sensory disturbances, but it is difficult to identify on magnetic resonance imaging (MRI). The aim of this study was to verify the usefulness of a characteristic MRI finding (slug sign) for identifying Morton neuroma and to clarify the relationship between excised neuroma characteristics and preoperative MRI findings.
Twenty-two web spaces were retrospectively assessed from the second and third intermetatarsal spaces of 11 feet of 10 patients (7 women and 3 men, aged average 59.5 years) who underwent surgical excision of Morton neuroma between 2017 and 2022. Asymptomatic web spaces were used as control. Neuromas with 2 branches of the plantar digital nerves on axial T1-weighted MRI (MRI-T1WI) were considered the slug sign. We investigated the preoperative presence of the slug sign in Morton neuroma and asymptomatic control web spaces. We also investigated the relationship between the maximum transverse diameter of the excised specimen and that estimated on coronal MRI-T1WI.
A total of 15 Morton neuromas were excised and assessed. The slug signs were present in 10 intermetatarsal spaces in 15 web spaces with Morton neuroma whereas the sign was found in 1 intermetatarsal space in 7 asymptomatic web spaces. The sensitivity and specificity for the slug sign to diagnose Morton neuroma was 66.7% and 85.7%, respectively. The positive and negative predictive values were 90.9% and 54.5%, respectively. The mean maximum transverse diameter of excised neuromas was 4.7 mm. The mean maximum transverse diameter of neuromas on coronal MRI-T1WI was 3.4 mm. A significant positive correlation was found between the maximum transverse diameters of excised specimens and diameters estimated on coronal MRI-T1WI ( = 0.799, < .001).
The slug sign may be a useful indicator of Morton neuroma on MRI to confirm nerve involvement after bifurcation.
Level IV, retrospective series.
Morton神经瘤是前足疼痛和感觉障碍的常见原因，但在磁共振成像（MRI）上难以识别。本研究的目的是验证一种特征性MRI表现（蛞蝓征）对识别Morton神经瘤的有用性，并阐明切除的神经瘤特征与术前MRI表现之间的关系。
回顾性评估了2017年至2022年间接受Morton神经瘤手术切除的10例患者（7名女性和3名男性，平均年龄59.5岁）11只脚的第二和第三跖骨间隙的22个蹼间隙。将无症状的蹼间隙用作对照。在轴向T1加权MRI（MRI-T1WI）上具有足底趾神经2个分支的神经瘤被视为蛞蝓征。我们调查了Morton神经瘤和无症状对照蹼间隙中术前蛞蝓征的存在情况。我们还研究了切除标本的最大横径与冠状面MRI-T1WI上估计的横径之间的关系。
共切除并评估了15个Morton神经瘤。15个有Morton神经瘤的蹼间隙中的10个跖骨间隙存在蛞蝓征，而7个无症状蹼间隙中的1个跖骨间隙发现了该征象。蛞蝓征诊断Morton神经瘤的敏感性和特异性分别为66.7%和85.7%。阳性和阴性预测值分别为90.9%和54.5%。切除的神经瘤的平均最大横径为4.7毫米。冠状面MRI-T1WI上神经瘤的平均最大横径为3.4毫米。在切除标本的最大横径与冠状面MRI-T1WI上估计的直径之间发现了显著的正相关（=0.799，<0.001）。
蛞蝓征可能是MRI上Morton神经瘤的一个有用指标，以确认分叉后神经受累情况。
IV级，回顾性系列研究。
