Birgitta Rosén

Tubular repair of the median or ulnar nerve in the human forearm: a 5-year follow-up

The long-term outcome from silicone tube nerve repair was compared with the outcome from routine microsurgical repair in a clinical randomized prospective study, comprising 30 patients with median or ulnar nerve injuries in the distal forearm. Postoperatively, the patients underwent neurophysiological and clinical assessments of sensory and motor function regularly over a 5-year period. After 5 years there was no significant difference in outcome between the two techniques except that cold intolerance was significantly less severe with the tubular technique. In the total group there was ongoing improvement of functional sensibility throughout the 5 years after repair. It is concluded that tubular repair of the median and ulnar nerves is at least as good as routine microsurgical repair, and results in less cold intolerance.

Upper limb amputees can be induced to experience a rubber hand as their own.

We describe how upper limb amputees can be made to experience a rubber hand as part of their own body. This was accomplished by applying synchronous touches to the stump, which was out of view, and to the index finger of a rubber hand, placed in full view (26 cm medial to the stump). This elicited an illusion of sensing touch on the artificial hand, rather than on the stump and a feeling of ownership of the rubber hand developed. This effect was supported by quantitative subjective reports in the form of questionnaires, behavioural data in the form of misreaching in a pointing task when asked to localize the position of the touch, and physiological evidence obtained by skin conductance responses when threatening the hand prosthesis. Our findings outline a simple method for transferring tactile sensations from the stump to a prosthetic limb by tricking the brain, thereby making an important contribution to the field of neuroprosthetics where a major goal is to develop artificial limbs that feel like a real parts of the body.

Tubular versus conventional repair of median and ulnar nerves in the human forearm: Early results from a prospective, randomized, clinical study

Injury to a peripheral nerve is followed by local synthesis and release of neurotrophic factors of importance for the regeneration process. This concept was adopted for repair of transected human median and ulnar nerves in the forearm. As an alternative to conventional microsurgical repair of the nerve trunk, silicone tubes of appropriate size were used to enclose the injury zone, intentionally leaving a gap measuring 3-4 mm between the nerve ends inside the tube. The early results from a prospective, randomized, clinical study comparing this principle with conventional microsurgical technique for repair of human median and ulnar nerves, is presented. Eighteen patients (14 men and 4 women), aged 12-72 (mean, 29.5) years, were randomized to either tubulization (11 cases) or conventional microsurgical repair (7 cases). A battery of tests for sensory and motor functions of the hand were carried out at regular intervals for up to 1 year after surgery. The results show no difference between the both techniques, with the exception of perception of touch, which showed a significant difference (p < .05) at the 3-month checkup in favor of the tubulization technique. At re-exploration 11 months after the initial procedure (1 case), the former gap was replaced by regenerated nerve tissue in direct continuity with the proximal and distal parts of the nerve trunk, the exact level of the former injury being impossible to identify. Study data demonstrate an intrinsic capacity of human major nerve trunks to reconstruct themselves in a preformed space when an optimal environment is offered and the surgical trauma is minimized.

Hand function after nerve repair.

Treatment of injuries to major nerve trunks in the hand and upper extremity remains a major and challenging reconstructive problem. Such injuries may cause long‐lasting disabilities in terms of lost fine sensory and motor functions. Nowadays there is no surgical repair technique that can ensure recovery of tactile discrimination in the hand of an adult patient following nerve repair while very young individuals usually regain a complete recovery of functional sensibility. Post‐traumatic nerve regeneration is a complex biological process where the outcome depends on multiple biological and environmental factors such as survival of nerve cells, axonal regeneration rate, extent of axonal misdirection, type of injury, type of nerve, level of the lesion, age of the patient and compliance to training. A major problem is the cortical functional reorganization of hand representation which occurs as a result of axonal misdirection. Although protective sensibility usually occurs following nerve repair, tactile discriminative functions seldom recover – a direct result of cortical remapping. Sensory re‐education programmes are routinely applied to facilitate understanding of the new sensory patterns provided by the hand. New trends in hand rehabilitation focus on modulation of central nervous processes rather than peripheral factors. Principles are being evolved to maintain the cortical hand representation by using the brain capacity for visuo‐tactile and audio‐tactile interaction for the initial phase following nerve injury and repair (phase 1). After the start of the re‐innervation of the hand (phase 2), selective de‐afferentation, such as cutaneous anaesthesia of the forearm of the injured hand, allows expansion of the nerve‐injured cortical hand representation, thereby enhancing the effects of sensory relearning. Recent data support the view that training protocols specifically addressing the relearning process substantially increase the possibilities for improved functional outcome after nerve repair.

Sensory feedback in upper limb prosthetics

One of the challenges facing prosthetic designers and engineers is to restore the missing sensory function inherit to hand amputation. Several different techniques can be employed to provide amputees with sensory feedback: sensory substitution methods where the recorded stimulus is not only transferred to the amputee, but also translated to a different modality (modality-matched feedback), which transfers the stimulus without translation and direct neural stimulation, which interacts directly with peripheral afferent nerves. This paper presents an overview of the principal works and devices employed to provide upper limb amputees with sensory feedback. The focus is on sensory substitution and modality matched feedback; the principal features, advantages and disadvantages of the different methods are presented.

Training with a mirror in rehabilitation of the hand

Treatment with a mirror gives an illusion of function in a missing or non-functioning hand. The method is based on the concept that the central representation of phantoms and body image can change rapidly, and has been described in the treatment of phantom pain and stroke. We show in three pilot cases new applications for the use of the mirror in rehabilitation after hand surgery.

Tubular repair of the median nerve in the human forearm. Preliminary findings

Transected median nerves in the forearm of two male patients, 12 and 21 years of age, were treated with a chamber technique leaving a 3 to 5 mm gap between the nerve ends. The nerve ends were enclosed in a silicone tube of such a dimension that would not cause compression of the nerve. Post-operative examination including sensory evaluation and assessment of muscle contraction force was carried out after 3 years. In both cases there was excellent motor recovery of the thenar muscles. Outgrowth of sensory fibres was remarkably fast, resulting ultimately in functional sensibility allowing almost normal hand function. 2PD was ⩽ 6 mm (12year-old patient) and 8 to 10 mm (21-year-old patient) respectively. In one case the silicone tube was re-explored because of minor local discomfort 2 years after the repair. The former gap was bridged by a smooth continuous nerve-like structure of the same diameter as the adjacent nerve trunk and with no signs of nenroma formation or compression of the nerve.

Online Myoelectric Control of a Dexterous Hand Prosthesis by Transradial Amputees

A real-time pattern recognition algorithm based on k-nearest neighbors and lazy learning was used to classify, voluntary electromyography (EMG) signals and to simultaneously control movements of a dexterous artificial hand. EMG signals were superficially recorded by eight pairs of electrodes from the stumps of five transradial amputees and forearms of five able-bodied participants and used online to control a robot hand. Seven finger movements (not involving the wrist) were investigated in this study. The first objective was to understand whether and to which extent it is possible to control continuously and in real-time, the finger postures of a prosthetic hand, using superficial EMG, and a practical classifier, also taking advantage of the direct visual feedback of the moving hand. The second objective was to calculate statistical differences in the performance between participants and groups, thereby assessing the general applicability of the proposed method. The average accuracy of the classifier was 79% for amputees and 89% for able-bodied participants. Statistical analysis of the data revealed a difference in control accuracy based on the aetiology of amputation, type of prostheses regularly used and also between able-bodied participants and amputees. These results are encouraging for the development of noninvasive EMG interfaces for the control of dexterous prostheses.

Recovery of Sensory and Motor Function After Nerve Repair A Rationale for Evaluation

In order to identify an effective test for evaluating the results of nerve repair, 25 patients, age 10-53 years (mean 27 years), were evaluated two to five years after median or ulnar nerve repair at the distal forearm level. The initial assumption was that evaluation after nerve repair should reflect four aspects of recovery: reinnervation, tactile gnosis, integrated sensory and motor functions, and pain or discomfort. The evaluation included a number of assessment methods addressing these aspects. Attention was paid to the usefulness of the tests with reference to their relevance for assessing hand functions. Clinical utility and possibilities for standardization and quantification of the results were considered important. Statistical analysis showed no correlations between the results obtained in clinical tests for reinnervation and the results from neurophysiologic examination. Grip strength and cold intolerance together accounted for a significant 51% of the variance in activities of daily living (ADL) capacity. Tactile gnosis correlated weakly with ADL capacity and strongly with age. Based on these findings, the following design for evaluating the result after median and ulnar nerve repair is suggested. To assess reinnervation: Semmes-Weinstein monofilaments and manual muscle-testing; to assess tactile gnosis: classic 2PD and a test with the features of the used shape identification test; to assess integrated functions: selected parts of Sollermans grip test and grip-strength test with Jamar dynamometer; to quantify pain and discomfort: a four-ranked scale for grading perceived problems from cold intolerance and hypersensitivity.

Sensory relearning after nerve repair

One of the challenges in reconstructive surgery is to ensure hand sensibility is regained after median nerve repair. We assessed tactile gnosis in 54 patients (mean age 32 [range 4-72] years) after repair of transected median or ulnar nerves at the wrist level. We found that there is a well-defined critical period for sensory relearning after nerve repair. There is an optimum capacity below age 5-10 years followed by a rapid decline, which levels out after puberty. The curve correlates with previously published data on critical periods for language acquisition among immigrants. Recovery of functional sensibility after nerve repair is based on a learning process and in many ways is analogous to learning a second language.