THE JOURNAL OF HAND SURGERY VOL. 20B No. 4 AUGUST 1995
T. LAWRENCE, P MOBBS, Y. FORTEMS and J. K. STANLEY
From the Hand and Upper Limb Centre. Wrightington Hospital, Wigan, UK
Radial tunnel syndrome results from compression of the radial nerve by the free edge of the supinator muscle or closely related structures in the vicinity of the elbow joint. Despite numerous reports on the surgical management of this disorder, it remains largely unrecognised and often neglected. The symptoms of radial tunnel syndrome can resemble those of tennis elbow, chronic wrist pain or tenosynovitis. Reliable objective criteria are not available to differentiate between these pathologies. These difficulties arc discussed in relation to 29 patients who underwent 30 primary explorations and proximal decompressions of the radial nerve. Excellent or good results were obtained in 70%, fair results in 13% and poor results in 17% of patients. The results can be satisfactory despite the prolonged duration of symptoms. We believe that a diagnosis of radial tunnel syndrome should always be born in mind when dealing with patients with forearm and wrist pain that has not responded to more conventional treatment. Patients with occupations requiring repetitive manual tasks seem to be particularly at risk of developing radial tunnel syndrome and it is also interesting to note that 66% of patients with on-going medico-legal claims had successful outcomes following surgery.
Journal of Hand Surgery (British and European Volume. 1995) JOB 4: 454-459
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The radial nerve contains a combination of motor, cutaneous sensory, proprioceptive and autonomic fibres (Lluch and Beasley, 1989; Sprofkin. 1954). The precise site of nerve compression and the nature and distribution of the involved axons determines the symptoms associated with radial tunnel syndrome These include pain in (he lateral extensor muscles with repeated pronation and supination, pain and sensory disturbance in the distribution of the superficial branch of the radial nerve, or diffuse wrist pain. There are three pathognomonic signs Intense tenderness is located over the radial nerve at the site of compression and pain may be induced by resisted extension of the middle finger and by resisted supination (Lister et al. 1979; Roles and Maudsley. 1972; Werner. 1979).
The anatomy of the radial tunnel and radial nerve has been extensively studied (Abrams et al. 1992; Fuss and Wurzl. 1991; Henry . 1957; Prasartritha et al. 1993: Roles and Maudsley. 1972: Spinner. 1968; Wilhelm. 1958) and is illustrated in Figure 1. The structures implicated in radial tunnel syndrome are shown in Table I. Sites of radial nene compression outside the radial tunnel include the fibrous arch of the long head of triceps (Lotem et al. 1971) and (he lateral head of triceps (Nakamichi and Tachibana. 1991). which should be considered in cases of atypical radial tunnel syndrome.
The results from surgical decompression of the radial nerve are generally satisfactory'. There are few reports however on the natural history of this condition. Kaplan (1984) found that after 5 years. 12 out of 15 patients with radial tunnel syndrome treated conservatively had complete resolution of their symptoms. Others, however, have noted the failure of conservative treatment after 9 months, then proceeded to surgery with encouraging outcomes (Moss and Switzer. 1983 ). The precise role of surgery remains to be established.
The operation
The extent of the radial nerve release is decided pre-operatively based on the symptoms of the patient and the site of maximal tenderness. Symptoms referred to the dorsal and radial aspects of the wrist arc probably due to irritation of (he superficial branch of the radial nerve (SBRN). Since this nerve always passes superficial to the arcade of Frohse. we can conclude that the site of irritation in these patients is proximal to the arcade where both the SBRN and the posterior interosseous nerves can be involved. It is therefore imperative to extend the release of the radial nerve proximal to the arcade of Frohsc and divide fascial bands when there are symptoms suggestive of SBRN involvement.
We also believe that the proximal limit of the release should incorporate the site of maximum tenderness. Al present, it is impossible to correlate precisely the pre operative site of maximal tenderness with the structures found intra-operatively It is, therefore, prudent to extend the release of the radial nerve proximal to the arcade of Frohsc when dense fascial bands arc seen, especially when symptoms in the distribution of the SBRN pre dominate. For these reasons, we now prefer an extended anterior approach (Green. 1793) to (he radial tunnel allowing safe access proximal io the arcade of Frohse.
Several other operations have also been described as a limited anterior exposure of supinator (Henry. 1957). transbrachioradialis approach (Roles and Maudsley. 1972) and a lateral approach (Capener. 1966).
Extended anterior exposure (Green. 1993)
A "lazy S” incision is made across the elbow joint lateral to biceps tendon The radial nerve is identified proximally between extensor carpi radialis longus and brachialis and followed distally to the Arcade of Frohsc. It is important to establish the anatomy and identify the radial nerve and its superficial branch. The arm is pronated and supinated to demonstrate the constricting structures and these are divided. The minimum intervention is a division of the fibrous arcade of Frohse. Exposure and release of the radial nerve from encasing proximal fascia can be undertaken with greatest certainty and safety using the extended anterior approach the drawback of this technique is the long scar across the elbow but m our experience. this is rarely a practical problem except occasionally in young women who are concerned about cosmetic appearance before the scar lades.
PATIENTS AND METHODS
Between 1978 and 1993. 33 patients were identified who had undergone primary exploration of the radial tunnel Wrightington Hospital One patient underwent bilateral radial tunnel release. 29 patients who had a total of 30 primary operations were reviewed either al pre arranged clinics or in their homes. Four patients were lost to follow-up. The medical records of the patients under review were scrutinised and the patients were examined by questionnaire, visual analogue scales and lamination. Grip and pinch strengths were recorded, and the incisions were assessed for tethering, tenderness and cosmetic appearance. In the group of patients with poor results, an attempt was made to establish the factors contributing to an unsatisfactory outcome.
16 were female and 13 male, with a mean age of 415 years (range 16 69). Follow-up from the time of surgery- ranged from I year to 10 years with a mean of 4 5 years. There were 12 tertiary referrals Delay in diagnosis prior to surgery ranged from 0 to 10 years (mean 3 years). Six patients had ongoing medico-legal claims The operated limbs were dominant in 26 cases and non-dominant in four. The right arm was operated on in 26 patients and the left in four.
Nerve conduction studies were undertaken in 19 patients and were positive in only six.
Clinical presentation
A wide variety of symptoms were found in this group of patients (Table 2). Pain m the region of the arcade of Frohse was the commonest, often in association with writer’s cramp I Department of Social Security Prescribed Disease A4). In our scries, writer’s cramp was defined as proximal forearm pain associated with writing, severe enough to prevent prolonged activity; the alternative definition of focal dystonia with bizarre postures was not seen. All patients had tenderness localised over the radial nerve, distinct from the lateral epicondyle thereby differentiating the condition from chronic tennis elbow Tenderness over the radial nerve in the flexor compartment is a common finding and it is therefore important to compare the seventy with the unaffected limb Three patients presented with a palsy of the posterior interosseous nene.
Patients describe the pain in the vicinity of ligament of Frohse as "constant aching” aggravated by or preventing activity. The distal symptoms in the region of the wrist or dorso-radial aspect of the forearm are poorly localised and consist of paraesthetic or burning sensations sometimes associated with painful finger or venous swelling.
Table 2:
Distribution of symptom associated with radial tunnel syndrome
Symptom .Vu
Proximal forearm pain near arcade of Frohse 20
Writers cramp* 17
Paraesthesia 12
Weakness of grip 9
Night cramp 7
Proximal radiation of pain into the arm 6
Distal radiation el pain into the hand 8
Pain in the distribution of the SBRS 5
Wrist tightness 3
Finger swelling 3
*See text for definition----------------------------
Occupation
The majority of patients had manual occupations requir ing repetitive pronation and supination (Table 3).
Previous diagnoses prior to radial tunnel release
Prior to the exploration of the radial tunnel, 20 out of 29 patients had received treatment for other suspected conditions (Table 4). Six patients underwent operative release of tennis elbow and three had undergone release of the first extensor compartment (de Quervain's tenovaginitis stenosans) without relief.
Operative exposures of the radial nerve
The number of patients undergoing full anterior expo sure of the radial nerve has increased recently. The exposures employed are summarized in Table 5.
Operative findings
Structures compressing the radial nerve were identified by pronating and supinating the forearm (Table 6). In some patients, several pathological structures were noted. No patients had evidence of permanent nerve injury, such as fibrosis, swelling or inflammation.
Table 3 - Occupations
Occupation No
Professional student 20
Assembly line workers 3
Heavy' goods fitters carriers 6
Housewife 3
Secretarial VDU operator 3
Labourer 2
Multiple occupations 2
Table 4 - Diagnoses prior to release of radial tunnel
Diagnoses No
Tennis elbow 16
Tenosynovitis 3
de Quervain's 3
Wartenberg's 3
Ulnar nerve compression 1
Cervical radiculopathy 1
Table 5 - Operative procedures for release of radial nerve
Anterior division of the arcade of Frohse only 14
Extended anterior release of radial nerve 13
Retrobrachialis approach to arcade to Frohse 3
Table 6 - Structures compressing the radial nerve
Structure No.
Tight arcade of Frohse 15
Dense proximal fascial bands 12
Tight superficial component of supinator 10
Compressive vessels 3
Nil of note 5
RESULTS
On the basis of visual analogue assessment, our results can be classified as follows: excellent 18 30 (60%). good 3 30 (10%), fair 4 30 (13%), and poor 5 30 (17%). A score of 0 refers to no improvement and 100 corresponds to complete recovery. We consider that scores of 80 to 100 are excellent results. 50 to 79 good. 20 to 49 fair and 19 or less represent poor results. In our series, one patient felt that her symptoms were aggravated by the operation. The results are summarized in Figure 2.
Functional outcome
Three patients presented with weakness of forearm extensor muscles, two of which made a full recovery and the third failed to improve. Pain was the predominant symptom in 29 out of 30 patients and restricted their activities. At review, 12 out of 29 patients (41%) were completely pain-free with all activities. Nine out of 29 (31%) patients fell that pain restricted only the most strenuous of activities, and eight out of 29 (28%) felt that light activity was restricted. These patients fell into the respective excellent, good, and poor result groups shown above.
Objective assessment
Two-point discrimination was initially assessed but was abandoned because of inconsistent results. There were no significant differences between operated and non operated hands regarding grip and pinch strengths.
PARAESTHESIA
12 patients were troubled with paraesthesia pre- operatively. Of these, one (8%) had complete resolution of symptoms, two (17%) had some improvement, and ten (85%) failed to improve significantly. One patient developed paraesthesia after the operation.
COMPLICATIONS
Three patients developed mild reflex sympathetic dys trophy which resolved with physiotherapy and guanethidine block. One patient developed a transient posterior interosseous nerve palsy which resolved after 6 months of conservative treatment. One patient developed a scar contracture following a post-operative infection which was revised using a Z-plasty. Two patients developed hyperaesthesia in the distribution of the superficial radial nerve. The remaining scars were well healed and asymptomatic.
ASSESSMENT OF POOR RESULTS
Four out of five patients with poor results at review had evidence of additional pathology. These included an avulsion fracture of the lateral epicondyle, a loose body in the elbow joint, severe cervical radiculopathy and a progressive palsy of the radial nerve of unknown aeti ology despite extensive neurological investigation (mononeuritis).
Three out of four patients with fair results also had evidence of additional pathology. One had ulnar impingement on the TFCC and is awaiting ulnar shortening, one had advanced first carpometacarpal arthrosis and the third had suspected Wartenberg’s syndrome. Release of the superficial branch of the radial nerve did not improve symptoms.
An attempt was made to assess which factors may be of predictive value regarding diagnosis and successful outcome. Only eight out of 14 men (57%) had successful procedures whereas 13 out of 16 (81%) of women were very satisfied with their operations. Five out of six patients with positive nerve conduction tests had good results. All patients with night pain had successful outcomes. Despite the presence of ongoing medico-legal claims, four out of six patients had good or excellent results.
DISCUSSION
Radial tunnel syndrome has been a recognised clinical entity for over 20 years. Capener (1966) described ten patients who underwent division of the arcade of Frohse because of chronic resistant tennis elbow. The first comprehensive account of this condition was given by Roles and Maudsley (1972). Subsequent series have been reported by Lister et al (1979). Moss and Switzer <1983). Hagert et al (1977). Ritts et al (1987) and Werner (1979).
Our study confirms previous reports regarding the diversity of symptoms associated with radial tunnel syndrome (Moss and Switzer, 1983). Pain is the commonest symptom and is usually located near to the site of compression over supinator. It can also be distributed to the dorsum of the wrist, dorso-radial aspect of the forearm and onto the volar aspect of the thenar eminence. This pattern of referred pain corresponds to the distribution of the posterior interosseous nerve to the carpus (Wilhelm. 1958) and to the distribution of the SBRN respectively. The distribution of the latter includes a variable area on the dorsum of the thumb, the carpus and first CM joint. A branch of the SBRN can also supply the skin over the thenar eminence (palmar cutaneous branch of the radial nerve).
Paraesthesia is often poorly defined and is often commented upon as a symptom not corresponding to known anatomical or pathological patterns. In our series, the release of the radial tunnel resulted in general improvement in pain, but only three out of 12 patients with paraesthesia were relieved of their symptoms. One patient developed paraesthesia secondary to the operation although the pain improved.
It is not currently possible to explain all the symptoms associated with radial tunnel syndrome as it involves the complex interrelationship of cutaneous, proprioceptive. motor and autonomic innervation. Finger swelling, painful venous dilation, dysaesthesia or allodynia (noxi ous sensations generated by non-noxious stimuli applied to normal skin) may be related to autonomic dysfunction as identified by Lluch and Beasley (1989). and Sprofkin (1954). The complexity is further illustrated by the observation that dysaesthesia following injury to the SBRN can be improved by division of the posterior interosseous nerve at the level of the wrist joint (Lluch and Beasley, 1989).
The pathophysiology of radial tunnel syndrome remains unclear. There are no rigid bony confines to the radial tunnel as found in carpal tunnel and cubital tunnel syndromes. Werner et al (1980), demonstrated pressures of 40 to 50 mm Hg exerted by a fibrous ligament of Frohse and these pressures rose to 190 mm Hg under tetanic muscle contraction. This is of sufficient magnitude to induce nerve ischaemia and blockade of nerve impulses. In addition, the fibrous ligament of Frohse may directly traumatize the radial nerve resulting in oedema and later fibrosis. Lister et al (1979) saw evidence of narrowing, hyperaemia and pseudoneuroma formation in six cases.
Excellent or good results for radial tunnel release range from 51% (Ritts et al. 1987) to 93% (Moss and Switzer. 1983). We found that 70"/,. of patients had good or excellent results. Ritts suggested that their •>oor results could be accounted for by the nature of the tertiary referrals and high incidence of worker's compensation at the Mayo clinic. We found that outstanding medico-legal claims did not adversely affect the clinical outcome although our numbers do not permit statistical analysis. We believe that seven out of nine patients with poor results had pathology other than radial tunnel syndrome, highlighting the need for improved patient selection and objective criteria for this disorder. Werner (1979) noted that lateral epicondylar tenderness, a positive middle finger extension test, a muscular arcade of Frohse, and evidence of nerve injury were associated with a poor prognosis. We found that the best prognosis was associated with women and patients with positive nerve conduction tests and night pain.
Having arrived at a diagnosis of radial tunnel syn drome, it is important to select the correct level for the release of the radial nerve. Pain over the dorsum of the wrist and over supinator is related to compression of the posterior interosseous nerve at the level of the arcade of Frohse. A limited anterior approach with division of the arcade will probably be adequate. If there are also symptoms in the distribution of the SBRN. the site of compression is probably proximal to the arcade of Frohse and therefore a more extensive release is required. For this reason, it is essential to determine the level of maximal tenderness pre-operatively and extend the release to that point. It is equally important to check for tenderness over the lateral head of triceps and at the level where the radial nerve passes through the intramuscular septum, two additional sites of compression. A comprehensive analysis of the correlation between the site of nerve compression and the associated signs was given by Fuss and Wurzl (1991).
We feel that it is unwise to undertake an extensive distal release of the SBRN even when symptoms suggest involvement of this nerve. In our unpublished series of Wartenberg’s disease, release of the SBRN proximal to the wrist was associated with a high incidence of reflex sympathetic dystrophy. A more proximal release of the SBRN may result in similar complications. Wartenberg’s disease (Wartenberg, 1932; Sprofkin 1954) is a monone uritis of the superficial branch of the radial nerve resulting from trauma of the nerve in its subcutaneous distribution. Compression can also occur as the SBRN pierces the deep fascia in the region of the tendinous intersection of brachioradialis and extensor carpi radialis longus (Mackinnon and Dellon. 1985).
We are looking for ways of improving patient selection. Fair or poor results can be due to incorrect diagnosis, incomplete release or irreversible nerve injury. In this series, four out of the five patients with poor results were probably incorrectly diagnosed. Unfortunately, nerve conduction studies are not sensitive or specific for diagnosing radial tunnel syndrome. Positive studies are useful in confirming the diagnosis and excluding cervical radiculopathy but the majority of tests are negative (12 out of 18 in our series) despite symptoms suggestive of significant compression (Ritts et al. 1987; Werner, 1979). Local injection of anaesthetic agents at the site of maximal tenderness has been reported (Ritts et al, 1987). It may be that this in combination with provocation testing will improve diagnostic accuracy.
Table 7—Possible presentations of radial tunnel syndrome
• Forearm pain radiating from the elbow to the wrist
• Chronic wrist pain with radial sided dysaesthesia
• Dorsal, radial, and occasional thenar sited wrist pain associated with swelling
• Failed tennis elbow treatment
• Failed de Quervain's release
• Wartenberg’s neuropathy (handcuff neuritis)
• Dorsal ‘tenosynovitis’ without crepitus or thickening
• Burning pain in the forearm and hand (autonomic dysfunction)
The role of nerve conduction studies (NCS) in the diagnosis of radial tunnel syndrome remains controversial. In most series the techniques used for the studies were not described or were incomplete. Ritts (1987) found that only 9% of patients had positive studies. Werner (1979) demonstrated that only 13 out of 25 patients with suspected pathology had electromyo graphic evidence of nerve compression but no significant difference was noted in outcomes with respect to the electromyographic findings. In our series, 33% of patients who had undergone NCS had positive results and of those, five out of six had excellent outcomes. Rosen and Werner (1980) demonstrated that static motor nerve conduction at rest was not significantly different in the symptomatic patients compared with an asymptomatic control group. A significant difference however was demonstrated on active weak supination (less than 2 Newtons of force). These findings suggest that radial tunnel syndrome can present at various stages; in the early stages, symptoms are intermittent with variable involvement of motor and sensory components, and in the later stages nerve damage increases and may eventually become irreversible. The results of nerve conduction studies simply reflect the stage of compression at presentation.
We conclude that the diagnosis of radial tunnel syndrome should be considered in the circumstances given in-Table 7. We also believe that there is a need to develop objective assessment techniques that will more accurately identify patients suffering from radial tunnel syndrome and localise the site of compression.
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Accepted: 18 August 1994
MrJ.K. Stanley. Hand and Upper Limb Centre. Wrightington Hospital. Hall Lane. Wigan. UK
© 1995 The British Society for Surgery of the Hand
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