Abstract
Morton’s neuroma is one of the most common pain syndromes affecting the forefoot. It is characterized by tenderness and burning pain in the plantar surface of the forefoot, with painful paresthesias in the two affected toes. This pain syndrome is thought to be caused by perineural fibrosis of the interdigital nerves. Although the nerves between the third and fourth toes are affected most commonly, the second and third toes and, rarely, the fourth and fifth toes can be affected as well. Patients may feel like they are walking with a stone in the shoe. The pain of Morton’s neuroma worsens with prolonged standing or walking for long distances and is exacerbated by poorly fitting or improperly padded shoes. As with bunion and hammer toe deformities, Morton’s neuroma is associated with wearing tight, narrow-toed shoes.
Keywords
Morton’s neuroma, Joplin’s neuroma, forefoot pain, perineural fibrosis, interdigital nerve, Mulder’s maneuver, Tinel sign, magnetic resonance imaging, diagnostic sonography, ultrasound guided injection
ICD-10 CODE G57.60
The Clinical Syndrome
Morton’s neuroma is one of the most common pain syndromes affecting the forefoot. It is characterized by tenderness and burning pain in the plantar surface of the forefoot, with painful paresthesias in the two affected toes. This pain syndrome is thought to be caused by perineural fibrosis of the interdigital nerves ( Fig. 130.1 ). Although the nerves between the third and fourth toes are affected most commonly, the second and third toes and, rarely, the fourth and fifth toes can be affected as well ( Fig. 130.2 ). Patients may feel like they are walking with a stone in the shoe. The pain of Morton’s neuroma worsens with prolonged standing or walking for long distances and is exacerbated by poorly fitting or improperly padded shoes. As with bunion and hammer toe deformities, Morton’s neuroma is associated with wearing tight, narrow-toed shoes.
Signs and Symptoms
On physical examination, pain can be reproduced by performing Mulder’s maneuver: firmly squeezing the two metatarsal heads together with one hand while placing firm pressure on the interdigital space with the other ( Fig. 130.3 ). In contrast to metatarsalgia, in which the tender area is over the metatarsal heads, with Morton’s neuroma, the tender area is localized to only the plantar surface of the affected interspace, with paresthesias radiating into the two affected toes. Patient may also exhibit a positive Tinel sign when the interdigital nerve is percussed from the plantar surface of the affected foot. Patients with Morton’s neuroma often exhibit an antalgic gait in an effort to reduce weight bearing during walking.
Testing
Plain radiographs, ultrasound imaging, and magnetic resonance imaging (MRI) are indicated in all patients who present with Morton’s neuroma, to rule out fractures and to identify sesamoid bones that may have become inflamed ( Fig. 130.4 ). MRI of the metatarsal bones is also indicated if joint instability, an occult mass, or a tumor is suspected. Ultrasound imaging may also aid in the diagnosis of Morton’s neuroma ( Fig. 130.5 ). Radionuclide bone scanning may be useful to identify stress fractures of the metatarsal or sesamoid bones that may be missed on plain radiographs. Based on the patient’s clinical presentation, additional testing may be warranted, including a complete blood count, erythrocyte sedimentation rate, and antinuclear antibody testing.
