Wartenberg syndrome refers to chronic compression of superficial branch of the radial nerve (SBRN) in the lower forearm and causes pain and burning sensation along the distal forearm, thumb , metacarpal and index finger.In the hand the area typically affected is dorsal hand, base of thumb and index finger with numbness, tingling and burning sensation description that may be indistinguishable from de Quervain's syndrome because it is NOT dependent on finger or hand motion. The SBRN in its subcutaneous course over the radial border of the wrist is a susceptible site for injury.Repetitive motions, tight wrist watches, casts and handcuffs, diabetes and iatrogenic ( steroid injections & treatment de Quervain's tenosynovitis and rare congenital variations), hypothyroidism and RA are known factors that increase the likelihood for this RARE mononeuropathy.
Cheiralgia ( for hand; ) was first described in 1932 by prestigious American Neurologist Dr Robert Wartenberg. Stopford(1922) and Matzdorrf(1926) published the rare clinical features and related their cases to tight wristlet watches. Wartenberg in 1932 was assigned the syndrome.
Physial examination reveals a positive Tinel's sign over the SBR over the area of brachioradialis attachment and styloid process area. A false +ve Finkelstein Test can be evoked by forearm pronation or ulnar deviation of the wrist. Hypoaesthesia in the SBR distribution is seen with weak grip & pinch grip strength , if one does a careful assessment.
Treatment is time!(1mm regeneration / month ) after removal of the constristing agent ( 'handcuff neuropathy') is usually sufficient-surgery is RARELY required as there is no motor component and they tend to improve with time. Recovery time is generally around 2 months after removal of the tight watch, jewellery etc. Complete anaesthesia suggests complete severance of the nerve and prompt exploration and repair is warranted.
Turkof E et al (J Hand Surg Am 1995 Jul;676-8) found that a variation in which the SBR N passes from under the fascia between the 2 slips of a split brachioradialis (BR)tendon occurred in 5 of 150 dissected arms and in 4 of 75 prosecuted cadaver specimens93.3%).In surgery this variation was found in 7 of 143 patients and they advised a thorough dissection at the site of the radial sensory nerve emergence from under the fascia and if the nerve emerges through a split BR tendon , this anomalous tendon slip should be divided.
Tryfonidis M et al ( Hand Surg 2004 Dec;9 (2):191-5) found a similar variation but also an anomalous communication between the SBRN and the lateral cutaneous nerve of the forearm. this possibly explained why the sensory loss in true Wartenberg's syndrome is minimal.These authors opined that WS is due to the SBRN passing through the split BR leading to potential compression of the nerve against the dorsal band and prevented longitudinal gliding movement during ulnar flexion.
Kandenwein JA et al (Ner venartz 2006 Feb;77(2)175-6, 179-180) reviewed 22 cases operated on over 10 years and in most cases the cause was tenolysis to treat de Quervain tenovaginitis stenosis.In 8 cases neurolysis was performed, in 4 cases reconstruction after neuroma excision and in 10 cases the neuroma was excised and transposition of the proximal nerve performed. Only 5 cases reported improvement. The best group (75 % improvement) was resection of of neuroma and transposition of the nerve stump.
Anatomy is critical in Neurosurgey! The SBRN is purely sensory and runs a constant course down the forearm under cover of the brachioradialis and turns dorsally at the mid-forearm piercing the fascia and becoming subcutaneous, dividing into 4-6 branches to supply the lateral 2/3 of the dorsal radial hand and dorsal surface of the radial 2 1/2 digits over the proximal phalanges .
Cheiralgia paraesthetica should be suspected in patients complaining of pain, numbness and paraesthesiae on the dorsal -radial aspect of the hand with characteristic findings. conservaetive avoidance of constriction and repetitive motion should see a recovery in about 2 months-as it is sensory surgery should be reserved for the rare case of complete anaesthesia.
In many ways CP is the upper limb equivalent of Meralgia paraesthetica (MP) in the lower limb- surgery MUST always be a LAST RESORT IN THESE PURELY SENSORY NEUROPATHIES.