Morton's neuralgia

Classification according to ICD-10
G57.6	Plantar nerve lesion - Morton's neuralgia (metatarsalgia)
ICD-10 online (WHO version 2019)

The Morton neuralgia , also called Morton metatarsalgia, Morton's syndrome or Morton's neuroma, is a painful condition in the area of the feet, on the basis of a compression (neural entrapment) of the plantar nerves ( nervi plantar of the tibial nerve ) between the heads of the means foot bones . As a result of this, the connective tissue surrounding the nerves can grow reactive ( perineural fibrosis ), which initially cushions the nerves from the bones, i.e. acts as a buffer, but can also become trapped in the long term.

It usually occurs between the metatarsal bones III and IV in the third space between the toes, more rarely between II and III. In up to 16% of cases, multiple Morton's neuralgia is also found on the same foot.

history

The first description of a neuroma in the intermetatarsal space was in 1835 by the Italian Filippo Civinini, while the first description of the symptoms goes back to Durlacher in 1845. The namesake T. G. Morton described metatarsalgia in 1876, which he assigned to the fourth metatarsophalangeal joint.

Anatomy and pathology

Histopathology. Surgical specimen of a fibrosed nerve in Morton's neuralgia. Connective tissue staining. Magnification 20x

In the beginning, a thickening of the connective tissue around the affected nerve in the sense of fibrosis or perineural fibrosis was often described; there are also studies that show accompanying demyelination and endoneural fibrosis, as well as thickening and swelling of the nerve. However, other studies found no difference to asymptomatic nerves. Likewise were ischemic changes described, but could also not be confirmed. Since there is no consistent pathological change in Morton's neuralgia, it is recommended to avoid the term “Morton's neuroma”.

In general, however, a mechanical constriction in the sense of a nerve compression syndrome of the interdigital nerve branch is considered the cause. The constriction and occasional thickening of the nerve is usually distal and plantar to the deep intermetatarsal ligament near the long flexor tendons.

While the interdigital nerves of the first and second space between the toes are branches of the medial plantar nerve and the interdigital nerve of the fourth space between the toes arises from the lateral plantar nerve , branches of both plantar nerves unite to form the interdigital nerve in the third space between the toes, which is therefore potentially larger and more vulnerable.

causes

Small nerve endings run between the heads of the metatarsals. If they are constantly irritated, a nerve knot can form, causing pain and numbness. The neuroma is thus a reaction of the plantar nerves to chronic mechanical stimulation e.g. B. when splayfoot and / or by constantly wearing too tight shoes and / or high heels . Histologically, there is often fibrosis in the nerve area in chronic ischemia .

Symptoms

Sensory disturbances in the ball of the toe of the forefoot. The patients initially feel a kind of furry feeling, which can later be accompanied by severe shooting pain.

diagnosis

Compression of the forefoot from both sides causes pain (Mulder's sign).

The clinical diagnosis is confirmed with ultrasound or magnetic resonance imaging before any surgery. The size of Morton's neuroma is important. Morton's neuromas with a transverse diameter smaller than 5 mm are often (approx. 30%) found in asymptomatic people. Often an additional or a differently localized Morton's neuroma (instead of between the second and third toe, between the third and fourth toe or vice versa) is found on ultrasound or magnetic resonance imaging. Therefore, after such examinations, the surgeon's approach is decisively influenced.

therapy

• Splayfoot treatment
• Local anesthesia relieves the pain immediately, but does not last long.
• Inlay with special relief for the affected intermetatarsal space.
• If the symptoms persist, surgical removal of the neuroma from the plantar or dorsal side.

literature

• Hans Assmus, Gregor Antoniadis (Hrsg.): Nervenkompressionssyndrome. Steinkopff, Heidelberg 2008, ISBN 978-3-7985-1818-6 , p. 139 f., Limited preview in the Google book search.
• Andreas B. Imhoff, Hans Zollinger-Kies (Ed.): Foot surgery. Thieme, Stuttgart et al. 2004, ISBN 3-13-123851-8 , p. 122 f., Limited preview in the Google book search.

Individual evidence

1. ↑ Carola Gessner: Chronic foot pain caused by neuroma. In: medical-tribune.de. Medical Tribune, June 29, 2015, accessed July 9, 2019 . 
2. ↑ H. Kuhn, R. Gerdes-Kuhn, H.-H. Küster: [link.springer.com/article/10.1007/s10302-003-0068-y On the history of the Civinini-Durlacher neuropathy, called Morton metatarsalgia. ] In: Foot & Ankle. Vol. 1, No. 4, 2007, pp. 269-272, doi : 10.1007 / s10302-003-0068-y (currently not available) .
3. ↑ ^{a b c} H. Waizy, C. Plaass, C. Stukenborg-Colsman: Die Morton's neuralgia. In: Foot & Ankle. Vol. 8, No. 4, 2010, pp. 231-239.
4. ↑ Mulder's Test. In: University of Michigan. Retrieved November 13, 2016 . 

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !