Brought to you by
ECR 2015 / B-0912
Can ultrasound replace MRI in assessment of nerve entrapment in osteofibrous tunnels in the upper extremity
This poster is published under an open license. Please read the disclaimer for further details.
Congress: ECR 2015
Poster No.: B-0912
Type: Scientific Paper
Keywords: Extremities, Ultrasound, MR, Diagnostic procedure
Authors: A. Abdel Maguid, Y. M. Tohamey, T. Taymour, L. Adel; Cairo/EG
DOI:10.1594/ecr2015/B-0912

Methods and materials

This study included forty patients; 28 females, 12 males with age range from 27 to 63 years (mean age 47 years). Thirty three patients were complaining of chronic refractory unexplained wrist pain, three patients were complaining of medial elbow pain, sensory symptoms in the ring and little fingers, three patients were complaining of pain in the posterior aspect of the shoulder, one patient was complaining of sensory deficits over the ulnar portion of the palm and wasting of the hypothenar eminence.

 

Patients were subjected to the followings:

• History taking and clinical provisional diagnosis.

• Electrophysiological studies (36 patients)

• Radiological investigations:

             Conventional unenhanced MRI.

             Ultrasonographic examination.

· Surgical relief was done for thirty two patients while eight patients had medical treatment and physiotherapy.

 

ULTRASOUND EXAMINATION:

All subjects were examined with GE logic 400-ultrasound machine using an 11MHz linear probe.

TECHNIQUE:-

The sonographic examinations were performed with the patient seated in a comfortable position facing the sonographer.

1.      At the shoulder:

In the supraspinous fossa, the suprascapular nerve is visualized as a small rounded hypoechoic structure lying between the scapula and the supraspinatus muscle. In the spinoglenoid fossa, the nerve is identified in a shallow depression of the scapula, the spinoglenoid notch, filled with hyperechoic fat.

 

2.     At the elbow:

The elbow is supported and placed in a flexed position.

The sonographic probe is placed at the level of the medial epicondyle.

The ulnar nerve at the cubital tunnel is identified as elliptical shaped structure of hypoechoic nature located superficial and posterior to the medial epicondyle.

 

3.     At the wrist:

The wrist is supported and placed in a slightly hyper extended position.

The sonographic probe is placed at the level of the distal skin crease.

In the axial plane, the ulnar artery is easily located medially and can ensure that the orientation of the axial images remains consistent.

The sonographic beam needs to be perpendicular to the surface of the flexor tendons.

The median nerve is seen as elliptical shaped structure of hypoechoic nature located superficial to the echogenic flexor tendons. Its size, shape, echogenicity and relationship to the underlying tendons and the overlying retinaculum are noted.

The ulnar nerve in the Guyon’s tunnel is located intimately related to the ulnar artery at the level of the pisiform.

Finger and wrist movements can be performed to assess the mobility of the median nerve.

 

INTERPRETATION DATA:

1.      At the suprascapular and spinoglenoid notches

     Depict the cause of compression which is most commonly ganglion cyst.

2.     At the cubital tunnel:

a.     Nerve cross-sectional area at the epicondyle:  Normally, it should be no more than 7.5 mm2

b.     Echo textural changes in the compressed ulnar nerve : The nerve becomes uniformly hypoechoic with loss of the fascicular pattern

c.     The presence or absence of masses should be noted

3.     At the Guyon’s tunnel:

a.      Echo textural changes in the compressed ulnar nerve: The nerve becomes uniformly hypoechoic with loss of the fascicular pattern

b.     The presence or absence of masses should be noted.

4.   At the carpal tunnel:

a.Cross sectional area : Calculated at the proximal carpal tunnel (scaphoid-pisiform level) by means of the ellipse formula [(maximum AP diameter) × (maximum LL diameter) × (Õ/4)]. Normally, it should not exceed 10 mm2.

b. Flattening of the median nerve : Calculated as the ratio of the nerve’s major to its minor axis (flattening ratio) (D1/D2). Normal flattening ratio should be less than 2.

c. Bowing of the flexor retinaculum : Bulging of the ligament can be appreciated with US and is measured at the distal tunnel (hamate-trapezium level). Once the tubercle of the trapezium and the hook of the hamate are identified, a line is drawn tangential to them and the distance between this line and the most anterior portion of the transverse carpal ligament is calculated:  Normally the distance is less than 4 mm.

d. Echo textural changes in the compressed median nerve: The nerve becomes uniformly hypoechoic with loss of the fascicular pattern

e. The amount of the synovial fluid and the presence or absence of masses should be noted.

 

MRI EXAMINATION:

MRI was performed using GYROSCAN INTERNA 1.5T MAGNET (PHILIPS) TECHNIQUE OF EXAMINATION

 

Patient position:

• The patients were scanned in the supine position, with the arm by the side of the body

• The dorsum of the hand parallel to the coronal plane of the magnet.

•Circular coil was used (C 200) placed over the wrist, elbow and shoulder joints, and was rapped and fixed by rubber bands.

 

 

  Protocol of MR imaging

Preliminary scout localizers in axial, coronal and sagittal planes were done.

1.      At the shoulder:

Sequence

FOV

Matrix/ Nex

Slice

TR

TE

TI

Axial proton FSE Fat Sat

10

512x256

2

4/0.5

3000

20

-

Coronal Oblique STIR

16-18

256x192

3

4/0.5

>1500

40

120

Coronal Oblique T1 SE Non Fat Sat

16-18

256x256 1

3/0.5

400-800

400-800

-

Sag oblique T2 FSE Non Fat Sat

16

256x256 2

3/0.5

>2000

110

-

2.     At the elbow:

Pulse sequence

TR

(msec)

TE (msec)

Gap

(mm)

Slice Thickness (mm)

FOV

(cm)

Matrix

TI

T1 WI FSE

(axial)

400-600

20

0.5

4

12-14

256x192

-

T2 WI FSE

(axial)

2000-4000

80

0.5

4

12-14

256x192

-

STIR

(coronal)

2000-6000

20-40

0.5

4

12-14

256x192

150

T2WI FSE

(sagittal)

2000-4000

80

0.5

4

12-14

256x256

-

3.     At the wrist:

Pulse sequence

TR

(msec)

TE (msec)

Gap

(mm)

Slice Thickness (mm)

FOV

(cm)

Matrix

T1 WI SE

(axial)

400-600

11-16

0.5

3

10-14

256x256

256x224

256x192

T2 WI SE

(axial)

3000-4000

85-102

0.5

3

10-14

256x256

256x224

256x192

 

·        TR: repetition time,

·        TE: echo time

·        TI: time of inversion recovery

·         FOV: field of view

 

MRI INTERPRETATION DATA:

The following items were assessed

1.      At the suprascapular and spinoglenoid notches:

•         Detect the cause of compression which is commonly ganglion cyst.

2.     At the cubital tunnel:

a.      Ulnar nerve signal alteration in T2 WI’s.

b.     Nerve swelling.

c.      Muscles signal alteration due to edema or fatty atrophy.

3.     At the Guyon’s tunnel:

a.      Ulnar nerve signal alteration in T2 WI’s.

b.     Nerve swelling.

c.      Edema and atrophy of the hypothenar, the third and fourth lumbricals, and interossei muscles

4.     At the carpal tunnel:

a.    Cross sectional area of the median nerve

•      Measured at the level of the pisiform and at the level of the radioulnar joint.

•      The size of the median nerve at the pisiform level is 1.6 to 3.5 greater than its size at the radioulnar joint in patients with carpal tunnel syndrome. 

b.          Flattening of the median nerve

•       Determined at the level of the hook of hamate bone. The flattening ratio is defined as the ratio of the major axis of the median nerve to that of minor axis.

•       The normal subjects demonstrate a flattening ratio less than 3 at the level of hamate.

c.      The bowing ratio:

•       It is distance of palmar displacement of the flexor retinaculum from a straight line drawn between the hook of hamate and the trapezium (X1) divided by the distance between the hook of hamate and the trapezium (X2).

•       Equation used was Bowing ratio= (X1/X2)X 100

•       The normal range measures 0-15%

d.   Signal pattern of the median nerve in T2-weighted images.

•         Normally it has intermediate signal compared to the low signal intensity tendons.

e.      Alteration of the signal intensity of the muscles due to edema or fat atrophy.

 

ELECTROPHYSIOLOGICAL STUDIES:

Nerve conduction studies were done with the site of stimulation selected according to the patient’s complaint and the clinical provisional diagnosis as follows:

1.      Suprascapular nerve:

The site of stimulation was at Erb’s point (2 cm above the midcalvicular point)

2.     Ulnar nerve

The site of stimulation was at the level of the wrist and around the elbow (below and above the elbow joint)

3.     Median nerve

The site of stimulation was at the level of the wrist

 

SURGICAL INTERVENTION:

1.      In Suprascapular nerve entrapment:

As the entrapment was caused by ganglion cysts in all our studied cases, arthroscopic excision of the cyst was performed as the method of decompression.

2.     In ulnar nerve entrapment:

a)    At the elbow:

Two cases underwent surgical decompression while one case was subjected to physiotherapeutic treatment.

b)   At the wrist:

One case underwent surgical decompression.

3.     In median nerve entrapment:

26 cases underwent surgical decompression while seven patients had medical treatment and physiotherapy

POSTER ACTIONS Add bookmark Contact presenter Send to a friend Download pdf
SHARE THIS POSTER
2 clicks for more privacy: On the first click the button will be activated and you can then share the poster with a second click.

This website uses cookies. Learn more