MR imaging of the forefoot: Morton neuroma and differential diagnoses

Magnetic resonance (MR) imaging of Morton neuromas is highly accurate. Morton neuromas are more conspicuous when the patient is prone positioned and the foot is plantar flexed than in the supine position with the toes pointing upward. MR imaging of Morton neuromas has a large influence on the diagnostic thinking and treatment plan of orthopedic foot surgeons. The most common differential diagnoses include intermetatarsal bursitis, stress fractures, and stress reactions. Some diagnoses (nodules associated with rheumatoid arthritis, synovial cyst, soft tissue chondroma, and plantar fibromatosis) are rare and can be diagnosed with histologic correlation only.     

Regression of Morton neuroma after local injection of steroids

Morton neuroma is a non neoplastic lesion corresponding to perineural fibrosis encircling the common interdigital plantar nerve. Several therapeutic approaches are possible: conservative treatment or surgery. We report a case treated by local steroid injection where follow-up MR showed near complete regression of the lesion. Although local injection of steroid is a classical treatment, it is the first time to our knowledge that resolution or such a striking diminution of size is reported after infiltration.     

Interdigital (Morton) neuroma: high-resolution MR imaging with a solenoid coil

Fifteen patients (17 feet) with symptoms suggestive of plantar interdigital neuroma underwent magnetic resonance (MR) imaging at 1.5 T with a solenoid forefoot coil with an 8-cm field of view. Surgery was subsequently performed on six feet. Fifteen interdigital masses were identified with MR imaging. Five of these, in feet that underwent surgery, were pathologically confirmed neuromas. In the remaining foot that underwent surgery, flexor tendon injury with probable inflammatory reaction was demonstrated with MR imaging but was interpreted as indeterminate for neuroma. No neuronal was identified at surgery, which otherwise confirmed the MR imaging findings. Neuromas were most conspicuous on T1-weighted images as foci of decreased signal intensity well demarcated from adjacent fat tissue. The lesions were poorly seen on T2-weighted images, where they appeared isointense or slightly hypointense to fat tissue in all cases. Prominent regions of increased signal intensity, presumably representing fluid in intermetatarsal bursae, were seen proximal to 10 of the 15 masses found with MR imaging.     

Morton neuroma: effect of MR imaging findings on diagnostic thinking and therapeutic decisions.

PURPOSE: To determine the effect of magnetic resonance (MR) imaging results on diagnostic thinking and therapeutic decisions by orthopedic surgeons in cases of a possible Morton neuroma. MATERIAL AND METHODS: Orthopedic surgeons completed a questionnaire before and after MR imaging for 54 feet in 49 patients thought to have Morton neuroma. Clinical diagnosis (Morton neuroma, differential diagnosis), location, diagnostic confidence, and therapeutic decisions were noted before and after MR imaging. The influence of the size of the neuroma on therapeutic decisions was analyzed. MR imaging diagnoses were compared with surgical results for 23 revised intermetatarsal spaces. RESULTS: After MR imaging, the clinical diagnosis of Morton neuroma was withdrawn in 15 of 54 (28%) feet. In 14 of 39 maintained diagnoses, the location or number of neuromas was changed after MR imaging. Confidence levels for Morton neuroma increased substantially after MR imaging. In 31 (57%) feet, a change in treatment plan resulted after MR imaging. Diameters of neuromas on MR images were significantly larger (P = .003) in surgically treated feet than in conservatively treated feet. MR imaging diagnoses were correct in all 23 revised intermetatarsal spaces. CONCLUSION: MR imaging has a major effect on diagnostic thinking and therapeutic decisions by orthopedic surgeons when Morton neuroma is suspected, especially because MR imaging helps in localization and size assessment of Morton neuromas.     

Morton neuroma: MR imaging in prone,supine, and upright weight-bearing body positions

PURPOSE: To assess the effect of prone, supine, and upright weight-bearing body positions on visibility, position, shape, and size of Morton neuroma during magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eighteen patients with 20 Morton neuromas underwent MR imaging of the forefoot in prone (plantar flexion of the foot), supine (dorsiflexion of the foot), and upright weight-bearing positions. Visibility (3 = good, 2 = moderate, 1 = poor), position relative to the metatarsal bone, shape, and transverse diameter of Morton neuroma were assessed on transverse T1-weighted MR images. Associations between different body positions and variables of interest were calculated with Wilcoxon signed rank test, chi2 test, and paired Student t test. RESULTS: In the prone position, visibility of all 20 Morton neuromas was rated with a score of 3; visibility in the supine and weight-bearing positions was inferior (mean score, 2.4). All 20 (100%) Morton neuromas changed their position relative to the metatarsal bone between prone and supine and between prone and weight-bearing positions. When compared with the prone position, there was a difference in the shape of all 20 Morton neuromas in the weight-bearing position (P <.001). Between prone (mean transverse diameter of Morton neuroma, 8 mm) and supine (mean transverse diameter of Morton neuroma, 6 mm) positions, the transverse diameter of Morton neuroma significantly decreased by 2 mm (P =.03); between prone and weight-bearing positions, the decrease of the mean transverse diameter was also significant (difference, 2 mm; P =.03). CONCLUSION: Morton neuroma appears significantly different during MR imaging in prone, supine, or weight-bearing positions. The transverse diameter of Morton neuroma is significantly larger on images obtained in the prone position than it is on images obtained in the supine and upright weight-bearing positions. Visibility of Morton neuroma is best on MR images obtained in the prone position.     

Shoulder impingement syndrome: sonographic evaluation

A method of shoulder sonography in which lateral and anterior elevation of the arm is used during scanning was demonstrated to be effective in cases of suspected impingement syndrome. The value of the method lies in its ability to demonstrate fluid collection in the subacromial-subdeltoid bursal system, with gradual distention of the bursa and lateral pooling of fluid to the subdeltoid portion while the arm is elevated. In 102 of 381 patients studied, surgical diagnosis was available for correlation. Among this group there were seven false-negative and three false-positive sonographic findings. A comparison of sonographic with surgical findings demonstrated a sensitivity of 81% and a specificity of 95% in stages I-III, and a sensitivity of 71% and a specificity of 96% in early stages I and II of the impingement syndrome. The results of dynamic shoulder sonographic examination with fluoroscopic radiography provide valuable information in patients with suspected early-stage impingement syndrome.     

Severe nonimmune hydrops fetalis: sonographic evaluation

Reported survival rates in nonimmune hydrops fetalis vary considerably. Among 27 fetuses exhibiting severe sonographic features of nonimmune hydrops fetalis, 33% survived the neonatal period. For five of the nine survivors, the prognosis remains uncertain or poor. On the basis of sonographic features alone neither prognosis nor potential survivors were reliably predicted.     

Amyotrophic lateral sclerosis: sonographic evaluation of dysphagia

Purpose

The authors sought to determine the role of video ultrasonography (VUS) in the diagnostic assessment of dysphagia in patients with amyotrophic lateral sclerosis (ALS).

Materials and methods

Nine patients underwent simultaneous static and dynamic VUS examination and videofluoroscopy (VFS) of swallowing.

Results

At the static phase, VUS showed 5/9 patients had lingual atrophy. Abnormal bolus position was observed in 6/9 patients at VUS and 3/9 at VFS. Both techniques identified an inability to keep the bolus in the oral cavity in 4/9 patients. At the dynamic phase, reduced lingual movement was observed in 5/9 patients at VUS and 2/9 at VFS. Disorganised tongue movement was seen in 3/9 patients at VUS and in 2/9 at VFS. Fragmented swallowing was only visualised at VUS. Stagnation of ingested material was never visualised at VUS, whereas it was clearly depicted in 2/9 patients at VFS.

Conclusions

VUS can be integrated into the diagnostic protocol for evaluating swallowing in patients with ALS, as it has higher sensitivity than VFS in assessing the dynamic factors that represent the early signs of dysphagia.     

Sciatic nerve: sonographic evaluation and anatomic-pathologic considerations

Sonographic analysis of the sciatic nerve was performed in vitro (anatomic specimen), in vivo (healthy volunteers), and in 16 patients with suspected peripheral sciatic nerve lesions. The ultrasound (US) examinations were performed with standard and high-resolution US equipment with linear-array configuration. The normal nerve displayed an echogenic fibrillar texture with round cross-sectional structure on both in vitro and in vivo sonograms. Satisfactory delineation of the nerve was obtainable in all cases. Nerve displacement was the main sonographic finding in cases of extrinsic compression. The lesion displayed variable echotexture, ranging from hypoechogenicity or mixed echogenicity in hematomata to hyperechogenicity in cases of fibrosis. Primary nerve tumors (neurofibroma) or infiltrating tumors (desmoid) caused clear disruption of the nerve structure. Use of sonography enabled assessment of the continuity of the nerve margins with the interposed graft in a case of reconstructive surgery. The potential to image sciatic nerve lesions noninvasively may have an important impact on diagnosis, treatment, and prognosis in symptomatic patients.