A Morton’s neuroma is a common cause of forefoot pain which often radiates into the toes, usually described as a burning or shooting type pain. Some intermittent numbness is also often experienced in the affected toes. Patients will often describe the sensation of having a small pebble under their forefoot when they walk.
This group of symptoms has been labelled “metatarsalgia”.
The pathology here involves the plantar digital nerve which can become trapped and impinged where it passes between the metatarsal heads and the transverse metatarsal ligament in the forefoot.
Over time, this impinged nerve becomes thickened and enlarged, creating the appearance of a neuroma. It is however technically not a neuroma because it is not a tumour, rather more correctly described as a perineural fibroma (nerve thickening). But the name “Morton’s neuroma” has stuck.
The most common site is the third webspace (between the third and fourth toes), followed by the second webspace. The other webspaces are infrequently affected.
Morton’s neuromas are commonly investigated with medical imaging, seen well with MRI and Ultrasound.
Our state-of-the-art Digital 3T MRI has the benefit of also imaging the bones, joints, tendons and muscles of the foot to help exclude any other cause for the presenting pain.
Ultrasound has the benefit of being a dynamic, real-time scan for example enabling the sonographer to manipulate the forefoot to help identify small neuromas which would otherwise be hidden. Qscan Qscan utilises the latest ultrasound technology from Canon Medical Systems to provide our patients with excellence in quality and accurate imaging.
The most common image-guided treatment option is Ultrasound guided injection of hydrocortisone and local anaesthetic (HCLA) around the Morton’s neuroma. This entails passing a fine needle adjacent to the affected nerve from the top of the foot or between the toes, not through the sole of the foot. Ultrasound guidance is used throughout to ensure the needle position is exact and the HCLA is delivered right around the nerve to achieve an optimal result.
Another treatment option involves radiofrequency ablation (RFA) of the affected nerve. This is sometimes considered for patients with recurrent symptoms who can’t have surgery or wish to avoid surgery. Under local anaesthetic and ultrasound guidance a radiofrequency ablation tipped needle is inserted into the Morton’s neuroma. The nerve is then ablated to reduce its thickness and prevent it being impinged.
Morton’s neuromas are unfortunately a common cause of forefoot pain in the community. MRI and Ultrasound often play a key role in the investigation, diagnosis and treatment of this pathology.
Dr Cameron Napper
Musculoskeletal MRI and ultrasound, Sports Medicine
Partner Radiologist- Qscan Radiology