What is it?
Neuroma is a thickened nerve, leading to entrapment neuropathy between the metatarsal heads. The most common site is between the third and fourth (3/4) metatarsals and known as a Mortons Neuroma. Often the second third space can be affected (2/3 Heuter Neuroma), rarely the fourth fifth.
The reasons why the 3/4 space is most affected relates to:
1. The communicating nerve branch, which is not present in everyone, between the medial and lateral planter nerves at the level of the 3/4 space, increasing the diameter of the nerve.
2. Tighter space between the 3/4 metatarsals.
3. Lack of mobility of the nerves that press on the ligament between the metatarsal heads.
How do I examine for Neuroma?
The first and most important thing to do is to ask the patient about the nature of the pain, as specific symptoms are the best clue to diagnosing correctly.
Key symptoms include:
1. Shooting pains into the toes
2. Worse with closed in shoes, better barefoot
3. Relieved by removing the shoe wiggling the toes
4. A feeling of “rumpled up socks” under the toes
With the patient non- weight bearing, check the range and quality of the toe joint motion. Does it feel stiff? Is that stiffness associated with grating or crepitus of the joint? Is there any swelling or pain on the top of the joint? If so there is a good chance the joint affected and less likely to be neuroma.
Grasp the medial and lateral foot with your left hand. As you squeeze the foot, press up into the interspace. Do you feel a click or pop? If so, this is possibly the neuroma passing between the metatarsal heads.
Imaging
The best imaging modality for diagnosing neuroma is ultrasound. The most important factor however is a clear description from the patient along with a positive clinical examination. Often ultrasound will yield false positive results, especially when carried out by a third party without clinical examination at the time of scanning. Often more than one neuroma is found and may be asymptomatic. As it is crucial to compare the clinical findings with US findings in real time we undertake our own US.
Reports will often state “neuroma/bursal complex”. This is due to the fact that nerve is generally Hyper-echoic (bright) and fluid is Hypo-echoic (dark). Whilst compression of the fluid helps distinguish between neuroma and bursa, it’s often not possible to be clearly definitive. The neuroma is usually surrounded by inflammatory fluid.
What treatment should I suggest?
Initially avoiding tight fitting shoes is helpful. Patients should be advised to wear shoes with a broad forefoot, lace up style. Minimising “slip on” type shoes that grip the forefoot can alleviate discomfort especially on prolonged walking.
Should this advice fail to improve things, injections can be considered. There are 2 types of injection that are best carried out under US guidance.
1. Steroid injection: The aim of these injections is to reduce the fluid and inflammation around the neuroma, identified by the Hypoechoic images. Evidence suggests that injecting steroid yields short term relief and that smaller neuroma <5mm may have longer lasting results. They can be useful diagnostic value.
2. Alcohol ablation: A series, usually 3-4, injections of alcohol mixed with local anaesthetic can be useful to dry and shrink the neuroma. This is a specialist treatment we offer and should only be done under US guidance. These injections may offer medium term relief, sometimes curative.
3. Surgical excision: This is the mainstay of treatment once conservative therapies fail. Either a dorsal or plantar approach can be used, with little difference in outcomes or risks. The decision is usually based on the foot shape and depth.
What is the recovery time?
Usually the patient rests the foot in a bandage and post-operative shoe for 2 weeks. After that a return to trainers and walking is permissible to tolerance. The patient should be encouraged to stretch and massage the toes to reduce swelling and scarring. Patients who undergo a plantar approach may require 3 weeks of rest before sutures are removed. Generally patients will be back to normal within 6 weeks.
What are the risks?
Short term risks include; infection, swelling and DVT (which is rare). Initial elevation of the limb in the first 2 weeks reduces swelling significantly.
Long term risks such as pain/stiffness and footwear restriction are also rare and can be improved by early mobilisation of the treated area.
How effective is the surgery?
In an audit of 1818 patients from my practice:
- 94.2% were better following surgery
- 2.6% were the same
- 2.1% a little worse
- 0.8% deteriorated
What tests should I request?
Avoid requesting separate ultrasound as this will be carried out at the time of examination.
Useful Websites to direct patients to:
Mortons Neuroma Patient Journey Book: https://www.amazon.co.uk/Mortons-Neuroma-Podiatrist-Patient-Journey-ebook/dp/B077R4VR6S
NHS information: https://www.nhs.uk/conditions/mortons-neuroma/
NICE guidance: https://cks.nice.org.uk/mortons-neuroma
About Consultant:
Antony N Wilkinson MSc, FCPodS, Consultant Podiatric Surgeon, please click here to visit profile.