Reinnerveration of free flaps used in oral and oropharyngeal reconstruction may provide a high level of sensory return. Spontaneous recovery of sensation in noninnervated flaps may also occur.
To evaluate the extent of spontaneous sensory return among patients who underwent radial forearm free flap reconstruction in the oral cavity and oropharynx.
A total of 40 patients were evaluated by 2 independent examiners. The median patient age was 60 years, and the median time from surgery was 47 months. A total of 29 patients had received postoperative radiotherapy. The mean flap size was 25 cm2. The following sensory modalities were tested: light touch, pinprick, hot and cold, and moving and static 2-point discrimination.
Recovery of sensation of at least 1 modality was noted in 32 patients (80%), however, only 5 patients (13%) had return of all 5 modalities. Eight patients (20%) had no sensory return. There was a trend to improved sensory recovery in flaps placed in the alveolar and retromolar trigone areas; however, on multivariate analysis, sensory return could not be predicted by any of the following factors: patient age, flap site, flap size, length of follow-up, and use of postoperative radiotherapy.
Complete sensory recovery was uncommon, unpredictable, and variable, although some recovery of sensation occurred in 80% of patients. It is not valid to rely on spontaneous sensory recovery for sensory innervation of free flaps. Correlation of sensory return with function is still needed.
THE USE OF radial forearm free flaps for reconstruction after resection of cancers of the oral cavity and oropharynx is now well established.1-3 In a previous article, O'Brien et al4 reported that the use of free flaps in head and neck reconstruction is associated with a reduction in surgical complication rates, especially fistulae, as well as a marked decrease in length of hospital stay. Furthermore, it has been demonstrated that elderly patients who are medically fit tolerate free flap surgery as well as younger patients do.5
Important areas of current focus are functional outcomes and quality of life among patients treated for head and neck cancers, and there is presently some debate about whether oral rehabilitation is compromised by lack of sensation in free flaps transferred to the oral cavity and oropharynx.6-8It has been demonstrated that excellent sensory recovery can be achieved by providing radial forearm flaps with sensory innervation by means of nerve anastomosis,9-11but spontaneous recovery of sensation has also been reported.6,12However, the relationship between sensory innervation and function has yet to be clearly established.
It has not been standard practice in the Department of Head and Neck Surgery, Royal Prince Alfred Hospital, Sydney, Australia, to reinnervate free flaps. Before incorporating this technique on a routine basis, we believed that the rate of spontaneous recovery of sensation should be established in our patient population. The purpose of the present study, therefore, was to evaluate the extent of spontaneous recovery of sensation in noninnervated radial forearm flaps used for oral and oropharyngeal reconstruction after resection of cancer.
Between 1987 and 1997, a total of 320 patients underwent free flap reconstructions after resection of head and neck cancers in our department. Two hundred sixty-seven of the reconstructions were radial forearm free flaps, 217 of which were used for reconstruction of the oral cavity and oropharynx. A subset of this group was randomly selected for inclusion in the present study. Eligibility criteria included the following: no evidence of active disease, geographical accessibility and willingness to participate, language skills and performance status adequate to allow good cooperation, and a minimum of 6 months of follow-up after reconstruction.
There were 40 patients in the study group: 26 men and 14 women (median age, 60 years; age range, 26-81 years). The median length of follow-up from date of surgery was 47 months (range, 7-108 months). Twenty-nine (73%) of the 40 patients underwent postoperative radiotherapy. The sites of reconstruction were the oral tongue (15 patients), floor of the mouth (11 patients), alveolus/retromolar trigone (7 patients), tonsil (3 patients), and soft palate (4 patients).
The 40 patients were tested by 2 independent examiners for the following sensory modalities: light touch, pinprick, hot and cold, and static and moving 2-point discrimination. The flap was tested, and the contralateral normal mucosa was also tested as a control. All sensory testing was performed in a quiet room, and examinations were carried out separately by 2 examiners who were blinded to each other's results. The radial forearm flaps were divided into 5 sectors for the purposes of the evaluation of sensation: a central area and 4 peripheral quadrants, which were tested separately.
Recovery of light touch was measured with Semmes-Weinstein monofilaments.13 A total of 5 monofilaments with markings from 2.83 to 2.65 were used. The markings represent the logarithm of 10 times the force in milligrams required to bow the monofilament. The filament was applied to the flap until it began to bend, and the measurement at which the patient noted sensation was recorded and converted into force (g/mm2). Pain sensation was tested using a 25-gauge needle. Temperature perception was recorded using indirect laryngoscopy mirrors that had been immersed in ice-cold water (40°C) and warm water (60°C). The presence of sensation in 3 of the 5 areas tested on each flap was regarded as being positive for the return of sensation in that modality. Two-point discrimination was measured using the points of a paper clip separated by a distance calibrated by a compass, with each distance being tested 10 times. The lowest value at which the patient correctly identified 1 or 2 points at least 7 out of 10 times was recorded as the value for 2-point discrimination.14
The radial forearm flaps varied in size from 8 to 48 cm2(mean, 25 cm2). Recovery of sensation in all modalities was detected in 5 patients (13%). Partial recovery in 1 or more modalities was present in a further 27 patients (67%). A total of 8 patients (20%) had no evidence of sensory recovery in any of the modalities.
Return of pinprick sensation occurred in 20 patients (50%), cold sensation in 16 patients (40%), and hot sensation in 8 patients (20%), and 2-point discrimination of less than 25 mm was present in 13 (34%) of 38 patients (2 flaps were regarded as being too small and inaccessible to evaluate for 2-point discrimination). The light-touch threshold using Semmes-Weinstein monofilaments showed an average of 47.3g/mm2, compared with a control of 17.7g/mm2.
Univariate analysis showed that the retromolar trigone and alveolar group had significantly greater return of hot and cold sensation (P<.05) and that there was a trend toward greater return of pinprick sensation in this group (P = .06). Multivariate analysis using logistic regression failed to demonstrate an independent relationship predicting return of sensation with the following factors: patient age, site of flap, size of flap, use of postoperative radiotherapy, and time to follow-up. There was no evidence that postoperative radiotherapy inhibited recovery of sensation or that sensation returned more frequently among patients who had not undergone irradiation.
In the present study, 32 (80%) of 40 patients had partial or complete recovery of sensation after reconstruction using noninnervated radial forearm free flaps. Complete recovery, however, was detected in only 5 patients (13%). These results correspond to those of the study of Vriens et al12that showed a 90% partial or complete sensory return in noninnervated free flaps in the oral cavity. Vriens and colleagues described a 73% return of cold sensation (hot was not tested), a 75% return of pinprick sensation, and a 36% return of 2-point discrimination, with a mean light-touch threshold of 75.1g/mm2, compared with 47.3g/mm2 in the present study.
Vriens and colleagues also showed no significant difference in sensory return in relation to patient age, sex, smoking, postoperative radiotherapy, or time of follow-up. However, in contrast to our results, which showed an increase return of sensation in the flaps in the immobile areas of the retromolar trigone and alveolus, they reported an increased sensory return in flaps on the tongue and floor of the mouth. Furthermore, they observed that recovery of sensation was greatest when the adjacent mucosa also had normal sensation.
Boyd et al11 have shown superior qualitative results using innervated free flaps in intraoral reconstruction, with 100% return of hot and cold sensation and 75% pinprick sensation. Two-point discrimination was equivalent to control values, with light touch approaching control values. The results of Boyd and colleagues were of particular interest because of the extraordinarily high level of 2-point discrimination recorded in the innervated flaps. Mean measurements of 3.5 mm for static and 2.4 mm for moving 2-point discrimination were recorded, similar to those of the residual tongue but far superior to those of the skin of the arm that was not surgically treated. The interpretation of the authors was that this finding implied that transferred tissue has the ability to increase its sensitivity when it is moved to a site of greater sensory complexity.
We can conclude from the present study that complete return of sensation occurs in a minority of patients and that, although the majority of patients regain some form of sensation, this outcome is unpredictable and variable in its extent. It would not be valid, therefore, to continue to avoid reinnervation of free flaps in the belief that sensory return will ultimately occur spontaneously.
The issue of function was not addressed in the present study, although we are currently evaluating functional outcomes in this patient group, with a view to evaluating speech intelligibility, eating habits, and swallowing. It will be necessary to collate these end points with the presence or the absence of sensory return before the true benefits of flap reinnervation can be determined.
Accepted for publication May 29, 1998.
Reprints not available from the authors.
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