Ultrasound Case of the Month

September 2013

53 year old female with right forefoot pain and

tingling in the toes

Sagittal Axial

Grayscale Images Through the Third Webspace

Grayscale Images Through the Third Webspace

+ D = 15.1 mmx D = 7.4 mm

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Sagittal and axial grayscale sonographic images at the level of the third metatarsal head demonstrate an

ovoid hypoechoic mass

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Diagnosis: Third Webspace

Neuroma

Neuroma Case Points

Neuroma Case Points

Tibial n.

Medial Plantar

n.Lateral

Plantar n.

• Fibrosis, local vascular proliferation, and edema adjacent to an enlarged digital branch of the medial or lateral plantar nerves

Neuroma Case Points

Tibial n.

Medial Plantar

n.Lateral

Plantar n.

• Fibrosis, local vascular proliferation, and edema adjacent to an enlarged digital branch of the medial or lateral plantar nerves

• Found on the plantar side of the transverse metatarsal ligament

Neuroma Case Points

Tibial n.

Medial Plantar

n.Lateral

Plantar n.

• Fibrosis, local vascular proliferation, and edema adjacent to an enlarged digital branch of the medial or lateral plantar nerves

• Found on the plantar side of the transverse metatarsal ligament

• Patients present with metatarsalgia

Neuromas: US• Typically hypoechoic on US

Neuromas: US• Typically hypoechoic on US• May be hypervascular on power

Doppler

Neuromas: US• Typically hypoechoic on US• May be hypervascular on power

Doppler• Can see continuity with the digital

nerve

Neuromas: US• Typically hypoechoic on US• May be hypervascular on power

Doppler• Can see continuity with the digital

nerve

Digital Nerve

Neuroma

Neuromas: US

• Typically hypoechoic on US• May be hypervascular on power Doppler• Can see continuity with the digital nerve• Sonographic Mulder’s sign: Palpable ‘click’

from the neuroma popping out of the intermetatarsal space upon tranverse compression of the metatarsal heads while the transducer applies pressure on the plantar surface of the neuroma

Neuromas: MRI

• Teardrop shaped

Neuromas: MRI

• Teardrop shaped• Iso/hypointense on T1 and

iso/hyperintense T2

Neuromas: MRI

• Teardrop shaped• Iso/hypointense on T1 and

iso/hyperintense T2 • May be associated with

intermetatarsal edema/bursitis

Neuromas: MRI

• Teardrop shaped• Iso/hypointense on T1 and

iso/hyperintense T2 • May be associated with

intermetatarsal edema/bursitis• Variable enhancement or

nonenhancing

Neuromas: Treatment

• Conservative: Modify footwear, US-guided steroid/lidocaine injection

Neuromas: Treatment

This 34 year old dancer has a history of two prior steroid injections of a second webspace neuroma. Note the foci decreased echogenicity consistent with scarring. Foci of increased echogenicity are related to microbubble formation and the inherent contrast effect of the steroid/ anesthetic mixture

Neuromas: Treatment

• Conservative: Modify footwear, US-guided steroid/lidocaine injection

• Advanced: Alcohol injections, radiofrequency ablation, and cryoablation

Neuromas: Treatment

36 year old male with a third webspace neuroma, status post prior steroid/anesthetic injection with only temporary relief

US guided placement of a cryoablation needle into the third webspace neuroma

Post cryoablation image with formation of an “ice ball” (see next slide)

Neuromas: Treatment

Cryoablation of neuromas typically involves 2-3 cycles of freezing with intervening shorter cycles of thawing, resulting in the formation of the characteristic “ice ball”

Neuromas: Treatment

• Conservative: Modify footwear, US-guided steroid/lidocaine injection

• Advanced: Alcohol injections, radiofrequency ablation, and cryoablation

• Surgical: Resection of the neuroma, interdigital nerve, and/or transverse metatarsal ligament release

References• Bencardino J, Rosenberg ZS, Beltran J, et al. Morton’s neuroma:

is it always symptomatic? AJR Am J Roentgenol 2000; 175: 649-653

• Hughes RJ, Ali K, Jones H, et al. Treatment of Morton’s neuroma with alcohol injection under sonographic guidance: follow-up of 101 cases. AHR Am J Roentgenol 2007;188: 1535-1539

• Quinn TJ, Jacobson JA, Craig JG, et al. Sonography of Morton’s Neuromas. AJR Am J Roentgenol 2000;174: 1723-1728

• Sofka CM, Adler RS, Ciavarra GA, et al. Ultrasound-guided Interdigital Neuroma Injections: Short-term Clinical Outcomes after a Single Percutaneous Injection- Preliminary Results. HSSJ, 2007;3: 44-49

• Neumann V, O’Connor RJ, Bush D. Cryoprobe treatment: an alternative to phenol injections for painful neuromas after amputation. AJR Am J Roentgenol, 2008;191: W313