Carpal Tunnel Syndrome-MRI

62 yr old house wife has clinical symptom of falling objects from the wrist with electrophysiological data of median nerve compression has reported for MRI. MR axial images show degenerative changes in the wrist in general , median nerve appears compromised within the canal with ratio of width to height nearly 2.0 and bowing of retinaculum with height of the canal at upper border of normal(1cm)

Radiological points of interest

Definition: fibroossoeus passage from palmar side connecting distal forearm to midlepalmar region

Contents: Total 9 tendons

Flexor digitorium profoundus 4

Flexor digitorium superficialis 4

Flexor pollicis longus 1

Nerve 1 = median nerve passes between FDP and FDS

 

FDP and FDS are enclosed in ulnar sheath and FPL is enclosed in radial sheath. From hook of hammate to trapezium tubercle extends the flexor retinaculum and the height of the canal is usually 10mm. Median nerve can show flattening (rep by increased width/ height ratio), ill defintion, more signal intensity on fat suppression (compared to hypothenar muscels ), and enhancement on CEMR, age related quantitative studies showed volume increase with age, anatomical variations and dynamics of flexion/ extension of wrist affect the relative space for median nerve. Newer developments include calculation of age related volume measurements, dynamic study of the joints, and posibly MR neurography.

Case by Dr MGK Murthy, Sr Consultant Radiologist

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