Median Forearm

A striking and unexpected outcome of the Cadmibel study was the clear-cut interference of fhe low-level Cd exposure with calcium metabolism. For example, when urinary Cd excretion increased twofold, serum alkaline phosphatase activity and urinary calcium excretion rose by 3-4% and 0.25 mmol/24h respectively [142]. The dose (CdU)-response rate of increased calciuria (>9.8 mmol/24h) suggested a 10% prevalence of hy-percalciuria when CdU exceeded 1.9 pg Cd/24h [38]. Hypercalciuria should be considered an early adverse tubulotoxic effect, because it may exacerbate the development of osteoporosis, especially in the elderly. A prospective study from 1992-1995 (median follow-up of 6.6 years) in the above-mentioned Cadmibel subcohort from the rural area showed for a two-fold increase in urinary Cd a significant (p<0.02) decrease of 0.01 g/ cm in forearm bone density in post-menopausal women. In addition, the relative risks associated with doubled urinary Cd were 1.73 (95% Cl 1.16-2.57 p=0.007) for fractures in women and 1.60 (0.94-2.72 p=0.08) for height loss in men. Cadmium excretion in the four... 

Pratap and colleagues in 2007 studied the effects of clonidine when added to lidocaine during subcutaneous infiltration of the forearm in a randomized controlled trial on 20 healthy volunteers [8j. They used lidocaine 0.5% on one forearm and lidocaine 0.5% with clonidine 10 pg on each patient s contralateral forearm. They found that clonidine significantly prolonged the duration of sensory blockade to pinprick (median time at least 6 hours) when compared to the lidocaine alone (median time 3.5 hours). 

Vignette 19. Carpal-tunnel median-nerve, and forearm ulnar-nerve, pressure neuropathies somewhat common in aged persons and often very treatable... 

Dahlin L, Lundborg G. The use of silicone tubing in the late repair of the median and ulnar nerves in the forearm. J Hand Surg (Br) 2001 26 393. ... 

Bertolotto M, Rosenberg I, Parodi RC et al (1996) Case report fibroma of tendon sheath in the distal forearm with associated median nerve neuropathy US, CT and MR imaging appearances. Clin Radiol 51 370-372 Bianchi S, Abdelwahab IF, Zwass A et al (1993) Sonographic findings in examination of digital ganglia retrospective study. Clin Radiol 48 45-47... 

Striking fusiform enlargement of the median nerve at the distal forearm through the palm, characterized hy an increased hulk of hyperechoic adipose tissue in the epineurium that surrounds and is interposed between normal-appearing fascicles (Fig. 4.5a-d) (Murphey et al. 1999 Chen et al. 1996). At the carpal tunnel level, the affected median nerve may become symptomatic earlier than other nerves due to its encroachment by the flexor retinaculum. In these instances, detection of nerve fascicles that appear focally swollen within the adipose mass indicates compression and the need for carpal tunnel release (Fig. 4.5e-g). Debulking of the mass may compromise the intraneural vasculature causing catastrophic motor and sensory deficits or an intense healing response that may further jeopardize function (Marom and Helms 1999). 

Fig. 4.7a,b. Hereditary neuropathy with liability to pressure palsies in a 42-year-old man with mild median and ulnar neuropathy, a Long-axis 12-5 MHz US image of the ulnar nerve (arrowheads) at the middle forearm with b schematic drawing correlation reveals mild fusiform thickening (arrows) of the nerve out of osteofibrous tunnels... 

Fig. 4.24. Plexiform neurofibromatosis. Long-axis extended-field-of-view 17-5 MHz US image over the median nerve (arrows) at the forearm in a patient with neurofibromatosis shows multiple plexiform neurofibromas (asterisks), some of which have a central hyperechoic area representing the target sign. The median nerve is markedly enlarged and shows a convoluted multinodular appearance...

Struthers , which joins the anomalous bony process and the medial epicondyle. Clinically, this condition typically affects young sportsmen as a result of intense muscular activity in the elbow and forearm and may start with pain and numbness in the first three fingers and weakness of forearm muscles innervated by the median nerve (Sener et al. 1998). US can demonstrate the relationship of the median nerve with the anomalous bone and ligament. Although not yet reported in the radiological literature, displacement of the nerve by these structures may represent an indicator of entrapment. Therapy includes excision of the ligament of Struthers and ablation of the supracondylar process. The brachial artery can also be compressed by an anomalous insertion of the pronator teres muscle into the supracondylar process (Talha et al. 1987). 

At the elbow, the brachial artery is superficial and courses along the medial border of the biceps muscle and tendon overlying the brachialis (Figs. 8.4b,c,8.5). Then, it passes between the median nerve (medial) and the biceps tendon (lateral) beneath the bicipital aponeurosis to divide, at the proximal forearm, into the radial and ulnar arteries. 

Although the soft tissue anatomy of the forearm is complex due to the high number of muscles involved in the spectrum of wrist and fingers movements, musculoskeletal pathology amenable to US examination is relatively uncommon in this area. Only a few specific conditions affecting the median nerve proximal to the carpal tunnel level merit separate consideration. 

The major nerves and vessels of the forearm are located within or traverse the volar compartment (Fig. 9.3). The median nerve enters the volar compartment passing between the superficial and deep heads of the pronator teres muscle. It then crosses the ulnar artery and proceeds toward depth to pass... 

The two main arteries in the forearm are the radial and the ulnar arteries, which are terminal divisions of the brachial artery (Fig. 9.3). The ulnar artery travels through the volar compartment with the ulnar nerve. It arises at the level of the neck of the radius, just medial to the distal biceps tendon, and courses deep to the sublimis bridge accompanied by the median nerve. At the middle third of the forearm, the ulnar artery traverses posterior to the median... 

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