Research: RADIAL TUNNEL SYNDROME - A RETROSPECTIVE REVIEW OF 30 DECOMPRESSIONS OF THE RADIAL NERVE

Updated: Dec 4, 2021


THE JOURNAL OF HAND SURGERY VOL. 20B No. 4 AUGUST 1995

Radial tunnel syndrome title

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.


SYMPTOMS OF RADIAL NERVE INJURY
SYMPTOMS OF RADIAL NERVE INJURY


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.

Fig 1 Anatomy of the radial tunnel

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

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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.

Fig 2 Graph demonstrating results based on visual analog assessment.

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 com