Stories from neuroanatomy: Morton’s Neuroma

This new series of blogs comprises 50 stories that emerge from neuroanatomy and its relationship to what we do in life. With the current focus on the brain, it seems that the rest of the nervous system has been forgotten. This, plus a chance to share clinical anecdotes from decades of neurodynamics work was an inspiration for the series. This first blog will be on Morton’s Neuroma.

Forgotten neural links in the foot

Morton neuroma, usually referred to Morton’s metatarsalgia is probably the most common nerve compression/irritation syndrome in the lower limb. The aetiology is a neuroma (growth, swelling of nerve, rarely carcinoma) in one of the common plantar digital nerves, usually the one to the third and fourth toes. This nerve arises from an anastomosis of the lateral branch of the medial plantar and a branch of the lateral plantar nerves. You won’t see this nerve connection on most anatomical drawings but it is present in most individuals (Jones & Klenerman 1984) and relevant to this story.

Betts in my home town of Adelaide was the first to report the aetiology (Betts 1940) of the syndrome – the symptoms of which  were initially reported by Morton in Philadelphia in 1876.  Sort of nice as I have lots of friends in Philly!

The problem is much more common in women and probably related to repetitive high heel trauma linked to forefoot hyperextension and stretch of the nerves and other tissues over the transverse metatarsal ligament, plus pinching due to tight shoes.

mortons-neuroma

Treatment via neurectomy has often been reported as failproof after Betts had 19/19 patients with complete relief of pain (that’s odd as neurectomy elsewhere in the body is often a disaster). A recent (and the only) prospective study (Bucknall et al. 2016) noted that only 63% of their cohort were painfree and they warned of the dangers of second surgery.

Most treatments suggested are invasive though a recent case study reports benefits from forefoot joint mobilisation (Sault et al. 2016).

A variant on the story

Why the nerve to the third and four toes? Well, if you go up and down on your tippytoes, the neural complex in the sole of your foot slides within neighbouring tissues but the tethering effect of the lateral/ medial plantar nerve connection may well minimise the movement and over time with pressure on the transverse metatarsal ligament, a neuropathy capable of mid axon discharge emerges. The tethering effect has been mentioned years ago by others (Graham & Graham 1984) but it makes more sense if you have an understanding of neurodynamics.

I have had repeated clinical findings of reproduction of metatarsalgia symptoms and/or limitations of movement when the forefoot and ankle are dorsiflexed and the leg straight leg raised. If the forefoot is pinched as in a tight shoe, adding SLR will often aggravate symptoms as you would expect.  High heel shoes offer a give and take to the plantar/tibial nerve complex – the ankle dorsiflexion forced by a high heeled shoe actually unloads the nerve at  the ankle while loading it at the forefoot. You may hear someone say that it is actually easier in high heels, which may hint at contributing issues higher up in the nerve.

Overall – leave surgery to the most recalcitrant states. Women should be off the heels for a time and men out of their pointy toed brothel creepers, to be graded back over time.  Get a nice pair of wide forefoot shoes like Campers. Wriggle and loosen up any stiff bits in the foot. Guide the nervous system so it moves and slides like the other side. And tell the nerve story to make sense of it for patients, remembering too that the term ’Morton neuroma’ is scary – nerve swelling, bursa around the nerve is less threatening.

 

Comments welcome. Keep an eye out for the second blog in this series – dural ligaments in the lumbar spine.

 

– David Butler

 

References

  • Jones JR & Klenerman L (1984) A study of the communicating branches between the medial and lateral plantar nerves. Foot Ankle 4:313-315.
  • Betts L (1940) Morton’s metatarsalgia: Neuritis of the fourth digital nerve. Med J Aust 1:514.
  • Bucknall V et al. (2016) Outcomes following excision of Morton’s interdigital neuroma: a prospective study. The Bone & Joint Journal. 98B: 1376-1381.
  • Sault J et al. (2016) Manual therapy in the management of a patient with a symptomatic Morton’s Neuroma: A case report. Musculoskelet Sci Prac 21: 307-310.
  • Graham CE & Graham DM (1984) Morton’s neuroma: A microscopic evaluation. Foot Ankle 5:150-153.

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16 Responses to “Stories from neuroanatomy: Morton’s Neuroma”

  1. Max Pietrzak

    Hi Dr Butler,

    Thoroughly enjoyed that, thank you, really good recap and with the newer science added. Also, the thought of a whole segment on dural ligaments is nothing short of mouth watering. Why stop at 50!?

    Max

    Reply
    • davidbutler0noi

      Hi Max, Thanks – there was a great response so we will continue the series. There is so much hidden, forgotten, but useful stuff to chat about. Other examples are ascending nerve roots in the upper thoracic spine or costoveretbral arthritis and the sympathetic trunk. Lots of nice work done in the 70’s 80’s and early 90’s before the focus went brainward.

      David

      Reply
      • Max Pietrzak

        Great, look forward to it. That will be a great supplementary online resource to the neurodynamic sections in your textbooks MOTNS and ‘The Sensitive Nervous System,’ really handy. Save some pennies to but the new ‘supercharged’ book!)

        Max

        Reply
  2. jqu33431quintner

    David, here is some more information on Thomas G Morton [1835-1903]. As you know, he published his classical paper in 1876 – “A peculiar and painful affection of the fourth metatarso-phalangeal articulation.” Morton described 15 cases, 13 of whom were women.

    Reference: American Journal of Medical Science 1876; lxxi:37

    His other claim to fame is that he performed the first operation in which a perforated appendix with an abscess was diagnosed and the appendix removed with a successful result.

    Reference:Singer C, Underwood EA. A Short History of medicine, 2nd ed. Oxford: Clarendon Press, 1962: 366.

    Reply
    • davidbutler0noi

      Hi John,
      Morton the allrounder? Maybe we are missing something these days with the demise of the allrounder – knowledge of other body parts and processes surely powers up knowledge of a speciality. In our world, it seems that surgeons often don’t realise that incisional alloydnia frequently persists in a particular group of people.

      Cheers

      David

      Reply
      • Max Pietrzak

        Out of interest David, what are your thoughts on specialization in neuro-musculoskeletal physiotherapy, to the level of one or two joints?

        Max

        Reply
        • davidbutler0noi

          Hi Max – do you mean clinical specialisation? If so it seems a waste of intellectual resources – how much can there be to know?

          David

          Reply
          • Max Pietrzak

            Yes, it perhaps is another form of the reductionist versus holistic debate. I have often wondered how much our profession, and to a large extent, our clinical practice, is resource driven (finance vs time).

            Reply
  3. John Barbis

    Yo Dave,

    One of your friends from Philly. I loved your phrase ” men out of their pointy toed brothel creepers”. Lots of images there!!!! TGD

    Reply
  4. Taryn Agius

    Hello Mr David Butler ! As you know I am more a “out on the water “ than “blog” person and though I rarely reply I do occasionally find the time to read some ( yours are always interesting ) ! I love your “brainward” move with chronic pain over the many years but very happy to see that all the conditions that respond so well to a little wiggle here and there to “clear the neural chain” and improve neurodynamic mobility, that you so well taught us in the very early 1990’s from top to bottom, are still getting the attention they very much deserve clinically – because they work ! Just a comment really about the Mortons and also the commonly presenting heel pains in regards to pressure from shoes etc – there is another increasingly common offender out there that I have now seen a few times – the ever evolving and increasingly used “socklet” in particular the very thin ones where the elastic is so thin it produces a very defined small compression over sensitive neural structures around the heel . I am sure others have noticed this but there seems to be thinner tighter elastic versions ( eek !) to these “socklets” and a move to wear them more so perhaps worth a mention !
    Taryn

    Reply
    • davidbutler0noi

      Hi Taryn,

      Thanks for that and great to hear from you! I didn’t think you wore shoes that often in North Queensland!
      I haven’t struck these super thin socklets yet , but its all about the notion of providing ‘mechanically permissable environments’ – locally at the nerve/ tissue interface and in life.

      All the best

      David

      Reply
  5. Gavin Johnston

    Hi David
    great article , love hunting around the peripheral for neuritis . One of the classic ascending causes of sciatic symptoms along with the superior tib/fib area.
    Love the NOI message
    Gavin J

    Reply
    • davidbutler0noi

      Thanks Gavin,
      As Taryn mentioned in the previous comment, we used to teach ‘clear the neural chain’ (and I still would if I was still teaching). So for a carpal tunnel syndrome with an altered neurodynamic test, you could be sent to the elbow, the plexus, shoulder stability, the thorax etc.

      Cheers

      David

      Reply
  6. Cassandra Zaina

    Hi Dave!

    I loved this, and I loved Taryn’s comments too. I haven’t come across those socklets either but will keep my eyes peeled.

    I thought I would just say that i really enjoyed reading your description of the movement vs tethering of the plantar nerves and their branches, that was very helpful. For the people I have seen with this problem (as you say usually females wearing high heels, but occasionally ‘toe-gripping runners’) I have also used dry needling into the thickened plantar area, with excellent effect. I wonder about all of the possibilities of why this helps so much. Obviously it is essential to get the foot moving and wiggle everything about as you have mentioned to prevent recurrence, as they are often stiff as a board.

    The dry needling seems to soften the hard ‘swelling’ immediately, with immediate subjective improvement in walking. I imagine it fires the feedback loop, hopefully resets the dorsal horn, might stimulate some circulation to create a healthier environment, perhaps ‘unsticks’ any layers of tissue that may have stuck together. I wonder what it does to the cortex!

    I would be interested in your views, and in the interests of your tootsies I hope you have restricted your high heel wearing to Friday and Saturday nights (laughing emoticon).

    Cass

    Reply

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