Ultrasound examination of the peripheral nerves of the extremity

This new modality of imaging diagnostics has a prominent role in everyday practice, in the differential diagnosis of peripheral extremity nerve defects, in planning the further diagnostic and therapeutic strategy.

Our specialist of peripheral neurosonography: Zsófia Farbaky MD. Office hours: Tuesdays 15:00 – 20:00. Please, contact our Customer Services to make an appointment.

The peripheral extremity nerves can be directly tested with high resolution ultrasound equipment, with high frequency, special 12-18 MHz linear transducer and with relevant experience and practice.

When performing an ultrasound scan, we perform measurements at a precise setting longitudinal and transversal plane and analyze the echo-structure of the nerve. We judge the size of the fasciculus, the continuity of the line of the nerve hull, the epineurium externum, its running and thickness. We examine the perineural and intraneural, the interfascicular veins, the vascularisation. We review the environment of peripheral nerve, the paraneurium.

Performing the neural sonographic (nerve ultrasound) tests requires great practical and theoretical knowledge, examining of nerves is complicated and time-consuming. Therefore, a detailed clinical, neurological examination, the establishment of the adequate indications, the specific problem statement, the region to be examined, marking the nerve (which limb, which nerve, which section, which tunnel is to be examined) prior to neurosongography is of utmost importance, and in some cases it is necessary to have a personal consultation between the clinician and the radiologist.

What to bring with you for the neural-ultrasound test?

An accurate, detailed anamnesis, the history of the patient and in postoperative cases and overview of the surgical description are indispensable for a neurosynographic examination.

It is very important, that not only the image but the pictorial documentation of the imaging studies must be also available; the patients must always bring it with them!

X-rays are also required: to view the exact location and mechanism of bone injuries, possible avulsion bone injuries, broken bone parts, the size of the callus formation.

In traumatic postoperative studies, it is important to see the location of osteosynthesis on the X-rays, the exact locations, number and sizes of the metal materials, plates, screws, and stapling wires.

Only in the possession of all the above knowledge can be performed a correct neurosonographic examination.

In the differential diagnosis of neuropathies, early diagnosis, the time factor, is crucial in judging the injury of the nerve!  It’s a great advantage of an ultrasonic testing that it can be used even then when ENG-EMG test cannot be made (not yet) or cannot be evaluated.

In postoperative traumatic cases, the nerve can be examined even besides any metal material.

Determining and marking the exact location of pathological changes and nerve injuries and mapping any possible anatomical variations are extraordinary help for surgical interventions. Ultrasonic testing is well suited for examining nerve injuries, to monitor and control the morphology of pathological anomalies.

Neurosonography can be used to detect hereditary neuropathies, developmental anomalies, compression lesions, traumatic injuries (traction, contusion, penetrating injuries, transsection and dissection), postoperative abnormalities, tumors.

The appearing pathological defection on the peripheral nerve: dimensional changes, abnormal shape and echo-structural differences. The nerve swells over the compression, the degree and extent of the swelling can be accurately measured which s proportional to the size of the pressure. The continuity (partial, full), and contour interruption can be seen, compression, dislocation. It is possible to examine the course of the nerve, its relation to the environment, its mobility.

In dynamic testing, we examine the nerve with ultrasound during the active and passive movement of the limbs, joints, muscles, tendons. The nerve adjusts to the movement of the limb or the joints and muscles with displacement in its surroundings, longitudinal sliding, and the fasciculas displacement on each other. The movement of the nerve and the intactness of the wavy, elongated intra- and extra-neural vessels are extremely important, since the nerve compression may cause severe sensory and motor impairment when scarring around the nerve.

Using dynamic examination one can determine the displacement, dislocation and instability of the nerve, the compressive effect of the variant muscle bundles around the nerve and abnormal messes, postoperative scarring, adhesion.

The importance of peripheral neurosonography is that it confirms or ratifies the clinical diagnosis thus so helps in the differential diagnosis of neuropathies.

Dealing with tunnel syndrome it can be told what causes the compression of the nerve, if there is a variant muscle, abnormal formula, fluid in the tunnel, and where the exact location of the compression is or there are multiple clamping.

In traumatic cases, it can be seen where the hematoma is that compressing the nerve, the soft tissue swelling, the broken or torn bone fragment. If there we have the continuity of the nerve or the symptoms are caused by the contusion, compression, traction.

In postoperative cases the location and the relation to the peripheral nerve of the bone fracture, callus, osteotomy, metal fastenings, plates, screws, stapling wires can be investigated. We are able to diagnose the nerve damage, compression, dislocation caused by metal materials. Ultrasonography can be used to select the exact location of nerve damage on the skin, which is of great help in surgical exploration.

After tunnel syndromes surgery scarring, adherence, inadequate transcision of the retinaculum, partial or insufficient neurolysis and nerve transposition, postoperative bleeding can be detected.

The role of the ultrasonic testing is extraordinary in detecting of the nerve tumors lying in the background of neurological symptoms as they appear sometimes tactile masses.

Extremity peripheral nerves that can be tested by ultrasound:

  • Upper extremity: nervusradialis, nervusulnaris, nervusmedianus
  • Lower extremity: nervusischiadicus (the piriformis tunnel cannot be tested), nervusfemoralis (in the region of inguinalis), nervusperoneus, nervustibialis.

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