Morton neuroma

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Morton neuromas are focal areas of symptomatic perineural fibrosis around a plantar digital nerve of the foot. The abnormality is non-neoplastic and does not represent a true neuroma. It may more correctly be known as Morton metatarsalgia. The condition is thought to be due to chronic entrapment of the nerve by the intermetatarsal ligament.

Epidemiology

It most often occurs in middle-aged individuals and is many times more common in women than men. ~30% of asymptomatic middle-aged persons have the radiologic-pathologic findings of a Morton neuroma. Symptomatic lesions tend to be slightly larger (mean 5.3 mm vs. 4.1 mm in one large series 1). Lesions >5 mm are very likely to be symptomatic. 10% of lesions are bilateral.

Clinical presentation

Patients typically present with forefoot pain which radiates from midfoot to toes 5. Symptoms are often progressive and worsened by activity.

Location

The 3rd web-space (between 3rd and 4th metatarsal heads) is the most commonly affected site. The 2nd web-space is less often involved while the remaining web-spaces are rarely involved.

Pathology

It is characterised by neural degeneration with epineural and endoneural vascular hyalinisation, and perineural fibrosis around an intermetatarsal nerve 2.

Radiographic features

Ultrasound

Typically seen as a round to ovoid, well-defined, hypoechoic lesion in the intermetatarsal space proximal to the metatarsal head 4.  A small proportion can have mixed echotexture 5.

MRI

Dumbbell/ovoid-shaped lesion at a similar position to that described on ultrasound.

  • T1: typically low-to-iso signal 1-2
  • T2: typically low signal but can sometimes be intermediate in signal
  • T1 C+ (Gd): tends to show intense enhancement

Treatment and prognosis

Ultrasound-guided interdigital injection of steroid and local anaesthetic has been demonstrated to have a relatively success rate 9.

Surgical excision can also be performed, also with a relatively high success rate (~ 80% 6).

History and etymology

It was initially described by Thomas Morton in 1876 4.

Differential diagnosis

US differential considerations include:

  • intermetatarsal bursa
    • extruding out in between the metatarsal bones on the plantar aspect of the foot
    • compressible

MRI differential considerations include:

  • -<p><strong>Morton neuromas</strong> are focal areas of symptomatic perineural fibrosis around a <a href="/articles/plantar-digital-nerve">plantar digital nerve</a> of the foot. The abnormality is non-neoplastic and does not represent a true neuroma. It may more correctly be known as <strong>Morton metatarsalgia</strong>. The condition is thought to be due to chronic entrapment of the nerve by the intermetatarsal ligament.</p><h4>Epidemiology</h4><p>It most often occurs in middle-aged individuals and is many times more common in women than men. ~30% of asymptomatic middle-aged persons have the radiologic-pathologic findings of a Morton neuroma. Symptomatic lesions tend to be slightly larger (mean 5.3 mm vs. 4.1 mm in one large series <sup>1</sup>). Lesions &gt;5 mm are very likely to be symptomatic. 10% of lesions are bilateral.</p><h4>Clinical presentation</h4><p>Patients typically present with forefoot pain which radiates from midfoot to toes <sup>5</sup>. Symptoms are often progressive and worsened by activity. </p><h5>Location</h5><p>The 3<sup>rd</sup> web-space (between 3<sup>rd</sup> and 4<sup>th </sup>metatarsal heads) is the most commonly affected site. The 2<sup>nd</sup> web-space is less often involved while the remaining web-spaces are rarely involved. </p><h4>Pathology</h4><p>It is characterised by neural degeneration with epineural and endoneural vascular hyalinisation, and perineural fibrosis around an intermetatarsal nerve <sup>2</sup>. </p><h4>Radiographic features</h4><h5>Ultrasound</h5><p>Typically seen as a round to ovoid, well-defined, hypoechoic lesion in the intermetatarsal space proximal to the metatarsal head <sup>4</sup>.  A small proportion can have mixed echotexture <sup>5</sup>.</p><h5>MRI</h5><p>Dumbbell/ovoid-shaped lesion at a similar position to that described on ultrasound.</p><ul>
  • +<p><strong>Morton neuromas</strong> are focal areas of symptomatic perineural fibrosis around a <a href="/articles/plantar-digital-nerve">plantar digital nerve</a> of the foot. The abnormality is non-neoplastic and does not represent a true neuroma. It may more correctly be known as <strong>Morton metatarsalgia</strong>. The condition is thought to be due to chronic entrapment of the nerve by the intermetatarsal ligament.</p><h4>Epidemiology</h4><p>It most often occurs in middle-aged individuals and is many times more common in women than men. ~30% of asymptomatic middle-aged persons have the radiologic-pathologic findings of a Morton neuroma. Symptomatic lesions tend to be slightly larger (mean 5.3 mm vs. 4.1 mm in one large series <sup>1</sup>). Lesions &gt;5 mm are very likely to be symptomatic. 10% of lesions are bilateral.</p><h4>Clinical presentation</h4><p>Patients typically present with forefoot pain which radiates from midfoot to toes <sup>5</sup>. Symptoms are often progressive and worsened by activity.</p><h5>Location</h5><p>The 3<sup>rd</sup> web-space (between 3<sup>rd</sup> and 4<sup>th </sup>metatarsal heads) is the most commonly affected site. The 2<sup>nd</sup> web-space is less often involved while the remaining web-spaces are rarely involved.</p><h4>Pathology</h4><p>It is characterised by neural degeneration with epineural and endoneural vascular hyalinisation, and perineural fibrosis around an intermetatarsal nerve <sup>2</sup>.</p><h4>Radiographic features</h4><h5>Ultrasound</h5><p>Typically seen as a round to ovoid, well-defined, hypoechoic lesion in the intermetatarsal space proximal to the metatarsal head <sup>4</sup>.  A small proportion can have mixed echotexture <sup>5</sup>.</p><h5>MRI</h5><p>Dumbbell/ovoid-shaped lesion at a similar position to that described on ultrasound.</p><ul>
  • -</ul><h4>Treatment and prognosis</h4><p>Ultrasound-guided interdigital injection of steroid and local anaesthetic has been demonstrated to have a relatively success rate <sup>9</sup>.</p><p>Surgical excision can also be performed, also with a relatively success rate (~ 80% <sup>6</sup>).</p><h4>History and etymology</h4><p>It was initially described by <strong>Thomas Morton</strong> in 1876 <sup>4</sup>.</p><h4>Differential diagnosis</h4><p>US differential considerations include: </p><ul><li>intermetatarsal bursa <ul>
  • +</ul><h4>Treatment and prognosis</h4><p>Ultrasound-guided interdigital injection of steroid and local anaesthetic has been demonstrated to have a relatively success rate <sup>9</sup>.</p><p>Surgical excision can also be performed, also with a relatively high success rate (~ 80% <sup>6</sup>).</p><h4>History and etymology</h4><p>It was initially described by <strong>Thomas Morton</strong> in 1876 <sup>4</sup>.</p><h4>Differential diagnosis</h4><p>US differential considerations include:</p><ul><li>intermetatarsal bursa<ul>

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