Morton's neuroma

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Morton's neuroma
Other namesMorton neuroma, Morton's metatarsalgia, Intermetatarsal neuroma, Intermetatarsal space neuroma [1] common plantar digital compressive neuropathy [2]
Neuroma de Morton.jpg
The plantar nerves.
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Morton's neuroma is a benign neuroma of an intermetatarsal plantar nerve, most commonly of the second and third intermetatarsal spaces (between the second/third and third/fourth metatarsal heads; the first is of the big toe), which results in the entrapment of the affected nerve. The main symptoms are pain and/or numbness, sometimes relieved by ceasing to wear footwear with tight toe boxes and high heels (which have been linked to the condition). [3] [4] The condition is named after Thomas George Morton, though it was first correctly described by a chiropodist named Durlacher. [5] [6]

Contents

Some sources claim that entrapment of the plantar nerve resulting from compression between the metatarsal heads, as originally proposed by Morton, is highly unlikely, because the plantar nerve is on the plantar side of the transverse metatarsal ligament and thus does not come into contact with the metatarsal heads.[ citation needed ] It is more likely that the transverse metatarsal ligament is the cause of the entrapment. [7] [8]

Though the condition is labeled as a neuroma, many sources do not consider it a true tumor, but rather a perineural fibroma (fibrous tissue formation around nerve tissue).

Signs and symptoms

Symptoms include pain on weight bearing, frequently after only a short time. The nature of the pain varies widely among individuals. Some people experience shooting pain affecting the contiguous halves of two toes. Others describe a feeling akin to having a pebble in the shoe or walking on razor blades. Burning, numbness, and paresthesia may also be experienced. [9] The symptoms progress over time, often beginning as a tingling sensation in the ball of the foot. [10]

Morton's neuroma lesions have been found using MRI in patients without symptoms. [11]

Diagnosis

Negative signs include a lack of obvious deformities, erythema, signs of inflammation, or limitation of movement. Direct pressure between the metatarsal heads will replicate the symptoms, as will compression of the forefoot between the finger and thumb so as to compress the transverse arch of the foot. This is referred to as Mulder's sign.[ citation needed ]

There are other causes of pain in the forefoot that often lead to miscategorization as neuroma, such as capsulitis, which is an inflammation of ligaments that surround two bones at the level of the joint. If the ligaments that attach the phalanx (bone of the toe) to the metatarsal bone are impacted, the resulting inflammation may put pressure on an otherwise healthy nerve and produce neuroma-type symptoms. Additionally, an intermetatarsal bursitis between the third and fourth metatarsal bones will also give neuroma-type symptoms because it too puts pressure on the nerve. Freiberg disease, which is an osteochondritis of the metatarsal head, causes pain on weight-bearing or compression.[ citation needed ] Other conditions that could be clinically confused with a neuroma include stress fractures/reactions and plantar plate disruption. [12] [13]

Histopathology

Microscopically, the affected nerve is markedly distorted, with extensive concentric perineural fibrosis. The arterioles are thickened and occlusion by thrombi are occasionally present. [14] [15]

Imaging

Though a neuroma is a soft-tissue abnormality and will not be visualized by standard radiographs, the first step in the assessment of forefoot pain is an X-ray to detect the presence of arthritis and exclude stress fractures/reactions and focal bone lesions, which may mimic the symptoms of a neuroma. Ultrasound (sonography) accurately demonstrates thickening of the interdigital nerve within the web space of greater than 3mm, diagnostic of a Morton's neuroma. This typically occurs at the level of the intermetatarsal ligament. Frequently, intermetatarsal bursitis coexists with the diagnosis. MRI can distinguish conditions that mimic the symptoms of Morton's neuroma, but when more than one abnormality exists, ultrasound has the added advantage of determining the precise source of the patient's pain by applying direct pressure with the probe. Ultrasound may also be used to guide treatment such as cortisone injections into the webspace, as well as alcohol ablation of the nerve.

Treatment

Conservative

Orthotics and improved footwear are the first-line treatments for Morton's neuroma. In addition to traditional orthotic arch supports, a small foam or fabric pad may be positioned under the space between the two affected metatarsals, immediately behind the bone ends. This pad helps to splay the metatarsal bones and create more space for the nerve so as to relieve pressure and irritation. However, it may also elicit mild uncomfortable sensations of its own, such as the feeling of having an awkward object under one's foot. Footwear and orthotics are most effective in neuromas that have existed less than four and a half months and are smaller than 4–5 millimetres (0.16–0.20 in). To prevent or treat Morton's neuroma, comfortable shoes that are sufficiently long and have a wide toe box, flat heel, and thick sole are recommended. [3]

Corticosteroid injections can relieve inflammation in some patients and help end the symptoms. For some patients, however, the inflammation and pain recur after some weeks or months, and corticosteroids may only be used a limited number of times because they cause progressive degeneration of ligamentous and tendinous tissues.[ citation needed ] About 30% of people who receive steroid injections go on to have surgery. According to a 2021 review, it is most effective in neuromas smaller than 6.3 millimetres (0.25 in). [16]

Sclerosing alcohol injections are an increasingly available treatment alternative if other management approaches fail. Dilute alcohol (4%) is injected directly into the area of the neuroma, causing toxicity to the fibrous nerve tissue. Frequently, treatment must be performed two to four times, with one to three weeks between interventions. A 60–80% success rate has been achieved in clinical studies, equal to or exceeding the success rate for surgical neurectomy, with fewer risks and less significant recovery. If done with more concentrated alcohol under ultrasound guidance, the success rate is considerably higher and fewer repeat procedures are needed. [17]

Radiofrequency ablation is also used in the treatment of Morton's neuroma. [18] The outcomes appear to be similar to, or even more reliable than, alcohol injections, especially if the procedure is performed under ultrasound guidance. [19]

A 2019 systematic review of randomised controlled trials found that corticosteroid injections or manipulation/mobilisation reduced pain more than control, extracorporeal shockwave therapy or varus/valgus foot wedges (which did not reduce pain more than control or comparison treatment, and pain reduction was not reported in any wider foot/metatarsal padding studies). The review also found no randomised controlled trials for sclerosing alcohol injections, radiofrequency ablation, cryoneurolysis or botulinum toxin injections; these were only assessed with pre-test/post-test case series, which do not measure the benefit of treatment beyond placebo or spontaneous improvement over time. [20]

Surgery

If non-surgical interventions fail, patients are commonly offered neurectomy, a surgery that involves removing the affected piece of nerve tissue. Postoperative scar tissue formation (known as stump neuroma) can occur in approximately 20–30% of cases, causing a return of neuroma symptoms. [21] Neurectomy may be performed using one of two general methods. Making the incision from the dorsal side (the top of the foot) is the more common method but requires cutting the deep transverse metatarsal ligament that connects the third and fourth metatarsals in order to access the nerve beneath it. This results in exaggerated postoperative splaying of the third and fourth digits (toes) resulting from the loss of the supporting ligamentous structure. This has aesthetic concerns for some patients and possible, though unquantified, long-term implications for foot structure and health. Alternatively, making the incision from the ventral side (the sole of the foot) allows more direct access to the affected nerve without cutting other structures. However, this approach requires a greater post-operative recovery time in which the patient must avoid weight-bearing on the affected foot, because the ventral aspect of the foot is more highly enervated and impacted by pressure when standing. It also carries an increased risk of scar-tissue formation in a location that causes ongoing pain.[ citation needed ]

When a patient has multiple neuromas in the same foot, the most common surgical approach is to remove them all using a single incision. [22]

Cryogenic neuroablation (also known as cryoinjection therapy, cryoneurolysis, cryosurgery or cryoablation) is a lesser-known alternative to neurectomy surgery. It involves the destruction of axons to prevent them from carrying painful impulses. This is accomplished by making a small incision (~3 mm) and inserting a cryoneedle that applies extremely low temperatures of between −50 °C to −70 °C to the nerve/neuroma, [23] resulting in degeneration of the intracellular elements, axons and myelin sheath (which houses the neuroma) with wallerian degeneration. The epineurium and perineurium remain intact, thus preventing the formation of stump neuroma. The preservation of these structures differentiates cryogenic neuroablation from surgical excision and neurolytic agents such as alcohol. An initial study showed that cryoneuroablation is initially equal in effectiveness to surgery but does not have the risk of stump neuroma formation. [24]

An increasing range of procedures are being performed at specialist centers to treat Morton's neuroma [10] [17] under ultrasound guidance. Studies have examined the treatment of the condition with ultrasound-guided sclerosing alcohol injections, [19] [25] radiofrequency ablation [18] and cryoablation. [26]

Related Research Articles

<span class="mw-page-title-main">Plantar fascia</span> Aponeurosis of the sole of the foot

The plantar fascia or plantar aponeurosis is the thick connective tissue aponeurosis which supports the arch on the bottom of the foot. Recent studies suggest that the plantar fascia is actually an aponeurosis rather than true fascia. It runs from the tuberosity of the calcaneus forward to the heads of the metatarsal bones.

<span class="mw-page-title-main">Plantar fasciitis</span> Connective tissue disorder of the heel

Plantar fasciitis or plantar heel pain is a disorder of the plantar fascia, which is the connective tissue that supports the arch of the foot. It results in pain in the heel and bottom of the foot that is usually most severe with the first steps of the day or following a period of rest. Pain is also frequently brought on by bending the foot and toes up towards the shin. The pain typically comes on gradually, and it affects both feet in about one-third of cases.

<span class="mw-page-title-main">Flat feet</span> Foot arch deformity

Flat feet, also called pes planus or fallen arches, is a postural deformity in which the arches of the foot collapse, with the entire sole of the foot coming into complete or near-complete contact with the ground. Sometimes children are born with flat feet (congenital). There is a functional relationship between the structure of the arch of the foot and the biomechanics of the lower leg. The arch provides an elastic, springy connection between the forefoot and the hind foot so that a majority of the forces incurred during weight bearing on the foot can be dissipated before the force reaches the long bones of the leg and thigh.

Occipital neuralgia (ON) is a painful condition affecting the posterior head in the distributions of the greater occipital nerve (GON), lesser occipital nerve (LON), third occipital nerve (TON), or a combination of the three. It is paroxysmal, lasting from seconds to minutes, and often consists of lancinating pain that directly results from the pathology of one of these nerves. It is paramount that physicians understand the differential diagnosis for this condition and specific diagnostic criteria. There are multiple treatment modalities, several of which have well-established efficacy in treating this condition.

<span class="mw-page-title-main">Achilles tendon rupture</span> Medical condition where the tendon at the back of the ankle breaks

Achilles tendon rupture is when the Achilles tendon, at the back of the ankle, breaks. Symptoms include the sudden onset of sharp pain in the heel. A snapping sound may be heard as the tendon breaks and walking becomes difficult.

Metatarsalgia, literally 'metatarsal pain' and colloquially known as a stone bruise, is any painful foot condition affecting the metatarsal region of the foot. This is a common problem that can affect the joints and bones of the metatarsals.

In human anatomy, the dorsalis pedis artery is a blood vessel of the lower limb. It arises from the anterior tibial artery, and ends at the first intermetatarsal space. It carries oxygenated blood to the dorsal side of the foot. It is useful for taking a pulse. It is also at risk during anaesthesia of the deep peroneal nerve.

<span class="mw-page-title-main">Nerve block</span> Deliberate inhibition of nerve impulses

Nerve block or regional nerve blockade is any deliberate interruption of signals traveling along a nerve, often for the purpose of pain relief. Local anesthetic nerve block is a short-term block, usually lasting hours or days, involving the injection of an anesthetic, a corticosteroid, and other agents onto or near a nerve. Neurolytic block, the deliberate temporary degeneration of nerve fibers through the application of chemicals, heat, or freezing, produces a block that may persist for weeks, months, or indefinitely. Neurectomy, the cutting through or removal of a nerve or a section of a nerve, usually produces a permanent block. Because neurectomy of a sensory nerve is often followed, months later, by the emergence of new, more intense pain, sensory nerve neurectomy is rarely performed.

<span class="mw-page-title-main">Neuroma</span> Benign tumor composed of nerve tissue

A neuroma is a growth or tumor of nerve tissue. Neuromas tend to be benign ; many nerve tumors, including those that are commonly malignant, are nowadays referred to by other terms.

Meralgia paresthetica or meralgia paraesthetica is pain or abnormal sensations in the outer thigh not caused by injury to the thigh, but by injury to a nerve which provides sensation to the lateral thigh.

<span class="mw-page-title-main">Radiofrequency ablation</span> Surgical procedure

Radiofrequency ablation (RFA), also called fulguration, is a medical procedure in which part of the electrical conduction system of the heart, tumor, sensory nerves or a dysfunctional tissue is ablated using the heat generated from medium frequency alternating current. RFA is generally conducted in the outpatient setting, using either a local anesthetic or twilight anesthesia. When it is delivered via catheter, it is called radiofrequency catheter ablation.

<span class="mw-page-title-main">Calcaneal spur</span> Medical condition of the heel

A calcaneal spur is a bony outgrowth from the calcaneal tuberosity. Calcaneal spurs are typically detected by x-ray examination. It is a form of exostosis.

<span class="mw-page-title-main">Morton's toe</span> Type of brachymetatarsia affecting the big toe

Morton's toe is the condition of having a first metatarsal bone that is shorter than the second metatarsal. It is a type of brachymetatarsia. This condition is the result of a premature closing of the first metatarsal's growth plate, resulting in a short big toe, giving the second toe the appearance of being long compared to the first toe.

A neurectomy, or nerve resection is a neurosurgical procedure in which a peripheral nerve is cut or removed to alleviate neuropathic pain or permanently disable some function of a nerve. The nerve is not intended to grow back. For chronic pain it may be an alternative to a failed nerve decompression when the target nerve has no motor function and numbness is acceptable. Neurectomies have also been used to permanently block autonomic function, and special sensory function not related to pain.

The transverse metatarsal ligament is a narrow band which runs across and connects together the heads of all the metatarsal bones. It is blended anteriorly with the plantar (glenoid) ligaments of the metatarsophalangeal articulations.

<span class="mw-page-title-main">Hallux rigidus</span> Arthritis and stiffness affecting the base joint of the big toe

Hallux rigidus or stiff big toe is degenerative arthritis and stiffness due to bone spurs that affects the metatarsophalangeal joints (MTP) at the base of the hallux.

<span class="mw-page-title-main">Tailor's bunion</span> Medical condition

Tailor's bunion, also known as digitus quintus varus or bunionette, is a condition caused as a result of inflammation of the fifth metatarsal bone at the base of the little toe.

<span class="mw-page-title-main">Mulder's sign</span> Medical condition

Mulder's sign is a physical exam finding associated with Morton's neuroma, which may be elicited while the patient is in the supine position on the examination table. The pain of the neuroma, as well as a click, can be produced by squeezing the two metatarsal heads together with one hand, while concomitantly putting pressure on the interdigital space with the other hand. With this technique, the pain of the Morton's neuroma will be localized strictly to the plantar surface of the involved interspace, with paresthesias radiating into the affected toes.

<span class="mw-page-title-main">Dorsal digital nerves of foot</span> Various nerve branches that supply the toes

Dorsal digital nerves of foot are branches of the intermediate dorsal cutaneous nerve, medial dorsal cutaneous nerve, sural nerve and deep fibular nerve.

<span class="mw-page-title-main">Nerve compression syndrome</span> Symptoms resulting from chronic, direct pressure on a peripheral nerve

Nerve compression syndrome, or compression neuropathy, or nerve entrapment syndrome, is a medical condition caused by chronic, direct pressure on a peripheral nerve. It is known colloquially as a trapped nerve, though this may also refer to nerve root compression. Its symptoms include pain, tingling, numbness and muscle weakness. The symptoms affect just one particular part of the body, depending on which nerve is affected. The diagnosis is largely clinical and can be confirmed with diagnostic nerve blocks. Occasionally imaging and electrophysiology studies aid in the diagnosis. Timely diagnosis is important as untreated chronic nerve compression may cause permanent damage. A surgical nerve decompression can relieve pressure on the nerve but cannot always reverse the physiological changes that occurred before treatment. Nerve injury by a single episode of physical trauma is in one sense an acute compression neuropathy but is not usually included under this heading, as chronic compression takes a unique pathophysiological course.

References

  1. ↑ Names for Morton's neuroma The Center for Morton's Neuroma
  2. ↑ Matthews, Barry G.; Hurn, Sheree E.; Harding, Michael P.; Henry, Rachel A.; Ware, Robert S. (2019). "The effectiveness of non-surgical interventions for common plantar digital compressive neuropathy (Morton's neuroma): a systematic review and meta-analysis". Journal of Foot and Ankle Research. 12 (1): 12. doi: 10.1186/s13047-019-0320-7 . PMC   6375221 . PMID   30809275.
  3. 1 2 Colò, Gabriele; Rava, Alessandro; Samaila, Elena Manuela; Palazzolo, Anna; Talesa, Giuseppe; Schiraldi, Marco; Magnan, Bruno; Ferracini, Riccardo; Felli, Lamberto (2020). "The effectiveness of shoe modifications and orthotics in the conservative treatment of Civinini-Morton syndrome: state of art". Acta Bio Medica: Atenei Parmensis. 91 (4–S): 60–68. doi:10.23750/abm.v91i4-S.9713. ISSN   0392-4203. PMC   7944831 . PMID   32555077.
  4. ↑ "Morton's neuroma - Symptoms and causes". Mayo Clinic. Retrieved 2019-03-03.
  5. ↑ "Thomas George Morton". Who Named It. Retrieved 2019-03-03.
  6. ↑ Morton's Neuroma: Interdigital Perineural Fibrosis Wheeless' Textbook of Orthopaedics
  7. ↑ Hochberg MC, Silman AJ, Smolen JS, Weinblatt ME, Weisman MH (2011). Rheumatology. 5th Edition, Volume 1, p. 794. Mosby Elsevier, Philadelphia. ISBN   978-0-323-06551-1
  8. ↑ A Scientific Discussion of Morton's Neuroma The Center for Morton's Neuroma
  9. ↑ "What is Morton's Neuroma?". The Center for Morton's Neuroma. 27 May 2014.
  10. 1 2 "Cryosurgery for Morton's Neuroma, UK Clinic".{{cite journal}}: Cite journal requires |journal= (help)
  11. ↑ Bencardino J, Rosenberg ZS, Beltran J, Liu X, Marty-Delfaut E (September 2000). "Morton's neuroma: is it always symptomatic?". American Journal of Roentgenology. 175 (3): 649–653. doi: 10.2214/ajr.175.3.1750649 . PMID   10954445.
  12. ↑ Gregg JM, Schneider T, Marks P (2008). "MR imaging and ultrasound of metatarsalgia--the lesser metatarsals". Radiological Clinics of North America. 46 (6): 1061–1078. doi:10.1016/j.rcl.2008.09.004. PMID   19038613.
  13. ↑ Gregg JM, Marks P (2007). "Metatarsalgia: an ultrasound perspective". Australasian Radiology. 51 (6): 493–499. doi:10.1111/j.1440-1673.2007.01886.x. PMID   17958682.
  14. ↑ Reed, RJ; Bliss, BO (February 1973). "Morton's neuroma. Regressive and productive intermetatarsal elastofibrositis". Archives of Pathology. 95 (2): 123–129. PMID   4118941.
  15. ↑ Scotti, TM (January 1957). "The lesion of Morton's metatarsalgia (Morton's toe)". AMA Archives of Pathology. 63 (1): 91–102. PMID   13381291.
  16. ↑ Choi, Jun Young; Lee, Hyun Il; Hong, Woi Hyun; Suh, Jin Soo; Hur, Jae Won (2021). "Corticosteroid Injection for Morton's Interdigital Neuroma: A Systematic Review". Clinics in Orthopedic Surgery. 13 (2): 266–277. doi:10.4055/cios20256. ISSN   2005-291X. PMC   8173242 . PMID   34094019.
  17. 1 2 "The Center for Morton's Neuroma".{{cite journal}}: Cite journal requires |journal= (help)
  18. 1 2 Chuter GS1, Chua YP, Connell DA, Blackney MC. (January 2013). "Ultrasound guided radiofrequency ablation in the management of interdigital (Morton's) neuroma". Skeletal Radiol. 42 (1): 107–11. doi:10.1007/s00256-012-1527-x. PMID   23073898. S2CID   25166343.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  19. 1 2 Hughes RJ, Ali K, Jones H, Kendall S, Connell DA (June 2007). "Treatment of Morton's neuroma with alcohol injection under sonographic guidance: follow-up of 101 cases". American Journal of Roentgenology. 188 (6): 1535–9. doi:10.2214/AJR.06.1463. PMID   17515373.
  20. ↑ Matthews, Barry G.; Hurn, Sheree E.; Harding, Michael P.; Henry, Rachel A.; Ware, Robert S. (13 February 2019). "The effectiveness of non-surgical interventions for common plantar digital compressive neuropathy (Morton's neuroma): a systematic review and meta-analysis". Journal of Foot and Ankle Research. 12 (12): 12. doi: 10.1186/s13047-019-0320-7 . ISSN   1757-1146. PMC   6375221 . PMID   30809275.
  21. ↑ "Morton's neuroma". www.nhs.uk. NHS choices. Retrieved 15 March 2016.
  22. ↑ Arshad, Zaki; Alshahwani, Awf; Bhatia, Maneesh (2022). "The Management of Multiple Morton's Neuromas in the Same Foot: A Systematic Review". The Journal of Foot and Ankle Surgery. 61 (1): 163–169. doi:10.1053/j.jfas.2021.08.003. PMID   34526223. S2CID   237536458.
  23. ↑ Cryosurgery Or Sclerosing Injections: Which Is Better For Neuromas?
  24. ↑ A Caporusso EF, Fallat LM, Savoy-Moore R (Sep–Oct 2002). "Cryogenic Neuroablation for the treatment of lower extremity neuromas". J Foot Ankle Surg. 41 (5): 286–290. doi:10.1016/S1067-2516(02)80046-1. PMID   12400711.
  25. ↑ Musson RE1, Sawhney JS, Lamb L, Wilkinson A, Obaid H. (March 2012). "Ultrasound guided alcohol ablation of Morton's neuroma". Foot & Ankle International. 33 (3): 196–201. doi:10.3113/fai.2012.0196. PMID   22734280. S2CID   43381926.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  26. ↑ Talia Friedman, MD, Daniel Richman, MD and Ronald Adler, MD (2012). "Sonographically Guided Cryoneurolysis Preliminary Experience and Clinical Outcomes". J Ultrasound Med. 31 (12): 2025–2034. doi:10.7863/jum.2012.31.12.2025. PMID   23197557. S2CID   2868415.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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