Early Experience with Morton s Neuroma

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1 Med. J. Cairo Univ., Vol. 80, No. 2, December: , Early Experience with Morton s Neuroma SAMEH BADRAN, M.D.; TAMER M. EWADI, M.D. and AMR ABDALKADER, M.D. The Departments of Neurosurgery*, Anaesthesiology** and Orthopedics Surgery***, Faculties of Medicine, Cairo*,*** and Al-Azher** Universities Abstract Background: When conservative treatment of a Morton neuroma is unsuccessful, surgical resection or a less invasive steroid injection is indicated. The purpose of the study was to evaluate the functional outcomes and patient satisfaction and, complications, after surgical resection via dorsal approach or local steroid injection of an interdigital neuroma. Methods: Thirty two consecutive patients who underwent surgical excision or local steroid injection of a Morton neuroma that had been unresponsive to conservative treatment were included in our study. Patients were selected based on The clinical diagnosis was confirmed by means of magnetic resonance imaging and histological analysis. Sixteen patients underwent excision of the neuroma through a dorsal approach; and sixteen patients were treated by local steroid injection, evaluation forms were handled to each patient and patient satisfaction scale was recorded to assess the results of both procedures. Conclusions: Surgical resection in of interdigital neuromata, in properly selected cases demonstrating a positive Mulder sign, or with a neuroma delineated on MRI scans; provides a reasonably safe treatment option with minimal complications. Key Words: Interdigital neuroma Morton s neuroma Local steroid injection. Introduction MORTON S neuroma is a benign lesion of an intermetatarsal plantar nerve, most commonly of the second and third intermetatarsal spaces, and although the name of Morton [1] is always associated with this lesion he was totally mistaken in explaining the symptoms as a painful affection of the fourth Metatarso-phalangeal joint articulation and in 1853 Civinii reported the clinical symptoms associated with it; patients complain of burning and/or numbness down the interspace of the involved toes; pain is usually made worse by walking in high-heeled shoes w/narrow toe box and is relieved by rest and by removing the shoe [3]. Correspondence to: Dr. Sameh Badran, The Department of Neurosurgery, Faculty of Medicine, Cairo University Interdigital neuroma has a higher prevelance in women particularly in the fourth and the fifth decades, between 2nd-3rd2nd (15-20%) interspace and 3rd-4th3rd (80-85%) metatarsal heads [4]. Treatment modalities include conservative measures as Nsaids, the use of orthotics, local injection and surgical excision. Pathoanatomy: The common digital plantar nerve to the 3 rd interspace is usually derived from the confluence of branches of the medial and lateral plantar nerves; the 3rd digital nerve may be predisposed to neuroma formation, since it is the largest digital nerve as it is formed by branches of both the medial and lateral plantar nerves and is a frequent site for development of interdigital neuromas the deep transverse ligament connects the plantar plates of the MTPjoints, and not the metatarsals themselves. The second and third common digital branches of the medial plantar nerve are the most frequent sites for its development [5]. Despite the name, the condition was first correctly described by a chiropodist named Durlacher [6]. and although it is labeled a "neuroma", many sources do not consider it a true neuroma, but rather a perineural fibroma or a type of nerve compression syndrome which involves the common digital nerves of the lesser toes [5]. Material and Methods The study was conducted at Doha clinic Hospital, Doha, state of Qatar. Thirty two patients with treatment of 32 feet were included in the study between August 2007 and August There were 27 female patients and only 5 males with a mean age of 48 years, range (30-65). 197

2 198 Early Experience with Morton s Neuroma Only patients who failed conservative treatment was included in the study all patients who showed improvement on conservative treatment and/or no recurrence of symptoms after 2 weeks of conservative management was excluded from the study. All patients were given NSAIDs, metatarsal pads, orthosis and proper footwear. patients who presented with bilateral symptoms due to affection of both feet was excluded from the study. Clinical examination and investigations: All patients presented with typical pain and burning, parthasias or numbness sensation among the forefoot with discretion to the toes, full neurological examination was done including SLR test. A positive Mulder sign was elicited in 27 patients Mulder sign is elicited when the forefoot is grasped with one hand to compress the transverse metatarsal arch the interspace is squeezed between the index finger and the thumb of other hand a palbable click is felt and recreate patient's symptoms it s probably due to the enlarged interdigital nerve as it moves under the transverse intermetatarsal ligament. MRI scan was then performed for each patient in order to confirm the presence of a neuroma in the affected interdigital space a neuroma was seen in 19 of the 32 feet also MRI scans of the lumbar spine were performed to patients with positive SLR test and patients with related pathologies of the lumbar spine or the nerve roots were excluded from the study. Injection technique: Injections were all conducted in the operation room. The patient is placed in a supine position with the knee in a supported flexed position (with a pillow beneath it) and the foot in a neutral position. The area of tenderness and fullness on the dorsum of the foot between the affected metatarsal heads is palpated. The needle is inserted on the dorsal foot surface in a distal to proximal direction, at an angle of 45 degrees, and down to the area of fullness between the metatarsal heads. A total of 3-5ml is injected into the space via a 25 gauge needle 2ml of 0.5% bupivacaine and 0.5ml of solumedrol. Position is very important, because plantar fat pad atrophy can occur if the fat pad is injected [7]. Patients were kept in the supine position for 5 minutes after the injection. And discharged 30 minutes after the injection, patients were advised to avoid any strenuous activity involving the injected region for at least 48 hours, and was give NSAIDs for 3 days after the injection as well as a metatarsal pad. A first follow-up examination within three weeks was arranged. Surgical technique: We utilized the dorsal approach in our resections it same technique utilized by Mann and Reynolds after adequate sterilization, draping and tourniquet application. A small skin incision at the dorsal aspect is placed corresponding to the affected interdigital space dissection goes through till the intermetatarsal ligament is reached and identified. The ligament is then served after application of self-retaining retractor. The digital nerve distal to the bifurcation to common digital nerve are served and common digital nerve is dissected proximally and distally as far as possible a loop magnifier is used during the dissection. Wound is then closed in layers and compression bandadge applied patient was instructed to elevate the leg for few hours then patient was allowed to weight bear using metatarsal pad and crutches for 2 weeks. Compression bandage was removed next day. Follow-up: Patients follow-up assessments and evaluation took place at Doha clinic Hospital. All patients were evaluated in the outpatient clinic at presentation as well as after conservative treatment then after each modality of treatment (injection or surgery) two methods of evaluation was utilized Coughlin criteria including pain, foot wear restriction and activity restriction [8] ; The Numeric Rating Scale (NRS), Verbal Descriptor Scale (VDS), and Faces Scale (FPS pain scale (Fig. 2). Patients where then classified at the final assessment which took place at least 6 months after treatment according to satisfaction into excellent, good, fair, poor. Evaluation forms were given to each patient and were filled by the patients in their final followup assessment data was evaluated accordingly. Results After evaluation of the forms handed to all of our patients, we were able to analyze the data at the time of final evaluation and the following results were obtained from all thirty two patients, sixteen patients underwent surgical resection for the neuromata while sixteen patients had local

Sameh Badran, et al. 199 injection. Tables (3,4) summarizes the functional results from all the patients that underwent the two modalities of treatment.

3 Sameh Badran, et al. 199 injection. Tables (3,4) summarizes the functional results from all the patients that underwent the two modalities of treatment. The overall patient satisfaction was assessed in our series and there were 7 patients of those who underwent local injection had excellent satisfaction (44%), when compared to 12 surgical resection patients who had excellent satisfaction (75%). With regards the complications 3 patients had superficial wound infection that responded to oral antibiotics, and 3 patients had toe numbness and 2 patients had scar tenderness. Fig. (1): Intraoperative excision of neuroma. No Mild Moderate Severe NRS VDS No Slight Mild Moderate Severe Extreme as bad as it could be FPS Fig. (2): Numeric Rating Scale (NRS), Verbal Descriptor Scale (VDS), and Faces Scale (FPS) [9]. Table (1): Evaluation form. Mild Moderate Severe scale 1,2,3 4,5,6 7,8,9,10 Physical Mild or no Interferes with Interferes with activity restriction some activity (sport) every day activity Footwear Can wear any Can t wear narrow No shoes is comfortable restriction type of footwear box shoes or high heels Table (2): Functional outcomes in injection patients. Table (3): Functional outcomes in surgical patients. Mild Moderate Severe Mild Moderate Severe 7 (44%) 7 (44%) 2 (12%) 15 (94%) 1 (6%) 0 Physical activity restriction 11 (69%) 2 (12%) 3 (19%) Physical activity restriction 14 (88%) 1 (6%) 1(6%) Foot wear restriction 10 (63%) 4 (25%) 2 (12%) Foot wear restriction 14 (88%) 2 (12%) 0

4 200 Early Experience with Morton s Neuroma Table (4): Complications. Complication Number of cases Wound Infection 3 Scar tenderness 2 Toe numbness 3 Discussion Several studies has dealt with Morton s neuroma [4,6,8] with only few neurosurgical publications. Our studies showed a female predominance as well as other studies These lesions most commonly occur between the third and fourth metatarsals, and then between the second and third [10-12]. Morton neuromas are uncommon between the first and second metatarsals and rare between the fourth and fifth [1,11]. Because they have a marked female predilection, delination of lesions in MRI is difficult and many and thus other causes of pain has to be excluded [13,14]. Zanetti et al. [15] suggested three MR imaging criteria for diagnosis of Morton neuroma: (a) the lesion is centered in the neurovascular bundle, within the intermetatarsal space, and on the plantar side of the transverse metatarsal ligament; (b) the lesion is well demarcated; and (c) the signal intensity of the lesion is similar to that of skeletal muscle on T1-weighted images and less than that of fat on T2-weighted images. In our series we used both modalities of treatment, local steroid injection and surgical resection, reserving the surgical option for patients with neuroma delineated on the MRI and positive clinical signs, from the 19 patients with lesion delineated on MRI, three patients didn t consent surgery and decided to undergo local injection we used the dorsal approach in all our patients who underwent surgery, the dorsal approaches has fewer complications and allows early mobilization [16] ; the results of Maurizio et al. [17] proofed the approach to be safe, effective and with no recurrence. Considering the difficulty diagnosis and in the absence of positive and uncertainty of MRI a local steroid injection is a less aggressive approach with reduced rate of complications; Zebouni et al. [18] reported regression of Morton neuroma after local steroid injection in one case. The overall results have shown a significant improvement in surgical patients over those who had chosen the local injection as a treatment modality, 75% and 44% respectively; Coughlin reported a sixty one percent excellent satisfaction in his series of sixty six cases [8]. Postoperative toe numbness occurred in three patients which reduces the patient satisfaction considerably especially in persistent cases. Numbness occurred mainly in the toes as well as the sole corresponding to the operated web space. We did not record any case of plantar keratosis occurring post-operative, probably because of the shorted duration of follow-up in this series. Comfort orthosis was given to all cases regardless of the modality of treatment used. Sixty three percent of the local injection patients had mild foot-wear restriction compared to eighty eight percent in the surgical resection group. Only six percent of either group had a major severe restriction in the choice of foot-wear requiring a special custom made insole. In view of these findings we believe that treatment of interdigital neuroma is easy and safe and the surgical resection in properly selected cases of interdigital neuromata, demonstrating a positive Mulder sign, or with a significant neuroma seen on the MRI provides a reasonably safe treatment option with minimal complications. References 1- MORTON T.G.: A peculiar and painful affection of the fourth metatarso-phalangeal articulation. Am. J. Med. Sci., 71: 37-9, MANN R.A. and REYNOLDS J.C.: Interdigital neuromaa critical clinical analysis. Foot Ankle, 3: , VILADOT A.: Morton s neuroma. Int. Orthop., 16: 294-6, MULDER J.D.: The causative mechanism in Morton s metatarsalgia. J. Bone. Joint. Surg. Br., 33: 94-5, CLIFFORD R. and WHEELESS, III.: editors Morton's neuroma [monograph on the Internet]. Wheeless text book of orthopedics; Available from http: / / www. wheelessonline. com/ortho/mortons_ neuroma_ interdigital_ perineural_fibrosis, DURLACHER L.: A treatise on corns, bunions, the disease of nails, and the general management of the feet. Philadelphia: Lea and Blanchard, 1845: BASADONNA P.T., RUCCO V., GASPARINI D. and ONORATO A.: Plantar fat pad atrophy after corticosteroid injection for an interdigital neuroma: A case report. Am. J. Phys. Med. Rehabil, 78: 283-5, MICHAEL J.: Coughlin, and Troy Pinsonneault, Operative Treatment of Interdigital Neuroma, a Long-Term Followup Study: The Journal of Bone and Joint Surgery (American) 83: , BIERI D., REEVE R.A., CHAMPION G.D., ADDICOAT L. and ZIEGLER J.B.: The Faces Scale for the selfassessment of the severity of pain experienced by children: Development, initialvalidation, and preliminary investigation for ratio scale properties., 41 (2): , 1990.

5 Sameh Badran, et al ALEXANDER I.J., JOHNSON K.A. and PARR J.W.: Morton s neuroma: A review of recent concepts. Orthopedics, 10: , MANN R.A. and REYNOLDS J.C.: Interdigital neuroma: A critical analysis. Foot Ankle, 3: , LASSMAN G.: Morton s toe. Clin. Orthop., 142: 73-84, KAMINSKY S., GRIFFIN L., MILSAP J. and PAGE D.: Is ultrasonography a reliable way to confirm the diagnosis of Morton s neuroma. Orthopedics, 20: 37-39, TURAN I., LINDGREN U. and SAHLSTEDT T.: Computed tomography for the diagnosis of Morton s neuroma. J. Foot. Surg., 30: , ZANETTI M., STREHLE J.K., ZOLLINGER H. and HODLER J.: Morton neuroma and fluid in the intermeta- tarsal bursae on MR images of 70 asymptomatic volunteers. Radiology, 203: , FARAJ A.A. and HOSUR A.: The outcome after using two different approaches for excision of Morton's neuroma. [abstract]. Chin. Med. J. (Engl). Aug., 123 (16): , Maurizio Valente, Marina Crucil and Vincenzo Alecci. Operative treatment of interdigital Morton's neuroma [abstract]. La Chirurgia degli Organi di Movimento Volume 92, Number , DOI: /s , HADDAD-ZEBOUNI S., ELIA D., AOUN N., OKAIS J. and GHOSSAIN M.: Regression of Morton neuroma after local injection of steroids [abstract]. J. Radiol. May, 87 (5): 566-8, 2006.

Aetiology: Pressure of Distal intermetatarsal ligament against common digital nerve. Lumbar radiculopathy Instability MTPJ joint or inflammatory MPJ

MORTON S NEUROMA 80% III web space (next common is II). Never occurs in III or IV Common in females in fifties Aetiology: Pressure of Distal intermetatarsal ligament against common digital nerve Rule out