Peripheral Nerve Surgery: Prevention and Management of Complications by Hand Therapy

23 Rehabilitation after Peripheral Nerve Surgery: The Hand Therapy Options

Ton A. R. Schreuders

Abstract

Meticulous surgical repair is only the first step after nerve injury after which a long process of rehabilitation will be required to regain a good hand function. After an initial period of protection of the nerve, many hours of training will have to follow to provide sufficient motor and sensory function and prevent complications. This chapter discusses the complications that can be avoided or treated by appropriate hand therapy.

Keywords: complications nerve surgery, hand therapy, nerve injuries, sensory re-education, relearning, hand rehabilitation

23.1 Introduction

The value of hand therapy has been shown in patients with peripheral nerve injuries; those who are treated by a hand therapist have a 3.5 times higher chance to return to work within a year than those who have not received this specialized form of therapy.1

Although it is common practice to protect the sutured peripheral nerve in the first 3 to 4 weeks by immobilization with a plaster cast, studies show contradicting results. The primary goal is to minimize tension on the repaired nerve(s) which has been proven to be harmful in experiments in dog trials.² Some advocate even longer periods of immobilization, i.e., 6 weeks for wrist-level nerve injuries.³ In contrast, other studies have shown no beneficial effect of immobilization on the recovery of digital nerves.⁴ Further research is warranted to evaluate if, and how, repaired nerves can be mobilized earlier.

After this initial protection phase, the splint is weaned of while tension on the nerve is gradually increased. Controlled movements to regain mobility must be exercised in combination with nerve gliding exercises to prevent short scars around the nerve.

23.2 Complications

23.2.1 Edema

Nerve injuries, like many other hand injuries, suffer from excessive swelling of the hand. Besides the nerve, often other structures like tendons and blood vessels are also damaged, causing poor circulation and subsequent swelling.

Treatment

For the management of edema, the usual care of elevation, compression gloves, movement, and massages are done, keeping in mind that patients should move their injured arm slowly and take account of what they feel when moving their arms, since the regular instruction of elevating the arm can cause tension on the sutured nerve. For example, a sutured median nerve will be stretched when the elbow is extended for elevation. In general, any pain and/or tingling sensation must be avoided in this early phase. Tight splint straps or bandages should also be avoided, especially at the suture sight of the nerve.

23.2.2 Pain

This is crucial and needs to be addressed in a multidisciplinary fashion and commences when the patient is undergoing nerve surgery. In order to prevent upregulation of the pain directly postoperatively, adequate pain regimes, preferably regional techniques, are imperative.

After a few days, the therapy protocol also needs to focus on minimizing pain when optimizing functional return, with the emphasis on active range of motion. In later stages, sensory and motor-relearning activities should be used to treat the pain.

After a peripheral nerve lesion, a non-noxious stimulus is sometimes perceived as being noxious, which is called allodynia.

Treatment

Electrical stimulation, e.g., transcutaneous electrical nerve stimulation (TENS), as used in chronic back pain, can be beneficial in patients with hyperesthesia. In desensitization strategies, different surfaces or textures are used to lower the pain caused by touching of the hand. The concept is similar to sensory re-education such that different types of stimulation, like vibration, and textures are used to re-educate and desensitize the area of hyperesthesia.

In contrast of desensitization strategies, somatosensory rehabilitation (SSR) of pain avoids stimulating the hypersensitive, painful area.⁵ In the SSR method, the skin area of the allodynia is mapped by allodynography and its severity by the rainbow pain scale which categorizes the severity with a series of monofilaments. Thereafter, a comfortable tactile or vibratory “counterstimulation” is given at a distant proximal zone and in time the painful area will become smaller.

Mirror therapy has also been shown to be effective in the treatment of complex regional pain syndrome (CRPS) type 2 caused by neuromas.

23.2.3 Muscle Strength Loss

Data supports the view that training protocols specifically addressing the relearning process substantially increase the possibilities for improved functional outcome after nerve repair.6 Trends in hand rehabilitation focus on modulation of central nervous processes rather than on peripheral nerve factors. Language learning is a thought-provoking metaphor to use when explaining this process of recovery to the patient, explaining the necessity of many hours of practice.⁷ Principles are being evolved to maintain the cortical hand representation by using the brain capacity for visuotactile and audiotactile interaction during the initial phase following nerve injury and repair.⁸

Full muscle power recovery is still rarely seen. Expectation management is important to prepare the patient for this. Fortunately, many patients learn to compensate for the loss of strength, although this automatic compensation can be counterproductive for the recovery.

The so-called disuse phenomenon is a very strong mechanism which can be observed in all patients. Patients learn quickly all kinds of trick movements and use compensatory movements to get the job done. Some of these movements help the patient to perform their activities of daily living but some can be counterproductive as the muscle power is not needed anymore.

Treatment

Like language learning, it takes hours of training and if possible can be used in a meaningful and purposeful way. In the first phase, muscle exercises are not the traditional fitness type of training but concentrated, short sessions of getting control of the right stimuli to the right muscle. Imagery and mirror therapy can also be helpful in this phase.

Therapists need to be aware of the disuse phenomenon mechanism and might consider treatment strategies like the constraint-induced movement therapy (CIMT) in which the noninjured arm is obstructed, e.g., with a splint or glove, which has been shown to be effective, e.g., in children with brachial plexus lesions.⁹

Electrical stimulation (ES) is common practice in some countries. The literature does not present strong clinical evidence to support the use of ES to maintain the muscle viability for reinnervation following a long duration of denervation. The mechanisms by which ES and/or exercise enhance nerve regeneration remain poorly understood; however, they do show accelerating nerve regeneration.¹⁰

A form of ES can be helpful in a phase when the nerve has reached the muscle but the patients cannot actively contract the muscle. In this situation, ES is used as a relearning option “finding” the right muscle.

23.2.4 Contractures and Shortening (E.g., Muscle Tightness)

In ulnar nerve lesions, especially in the supple hypermobile hands, there is a danger for progressive proximal interphalangeal (PIP) joint contractures due to inability to extend the PIP joints. The overaction of the extensor digitorum communis (EDC) creates hyperextension in the metacarpal phalangeal (MCP) joints of the fourth and fifth finger. Similarly, flexor tightness occurs which by itself increases the risk for PIP flexion contractures and vice versa. In longstanding intrinsic minus hands, even boutonniere deformities and extensor tendon luxation at the MCP joint level can occur.

In median nerve lesions, there is a danger of thumb web adduction contractures in the very early phase. In high median nerve palsy (Pointing Finger, Fig. 23‑1), an extension contracture of the IP joints of the index finger and IP joint of the thumb often takes place.