Upper Limb Function in Spinal Cord Injury

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Original Editor - Dr. Jennifer Dunne Top Contributors - Naomi O'Reilly, Admin and Kim Jackson  

Introduction

Improvement in upper limb function is identified as a top priority for people with tetraplegia following spinal cord injury. Management of the tetraplegic upper limb aims to maximize hand function to enable performance of daily tasks as independently as possible.  In order to reach this goal it is important to prevent secondary complications of the upper limb occurring in the acute phase. Therefore interventions need to start early and involve all members of the rehabilitation team. Initial intervention aims to prevent secondary complications of restricted joint movement, pain, swelling and contracture. Following this, rehabilitation of the tetraplegic upper limb consists of strengthening remaining muscles and retraining skills using motor relearning, compensatory and adaptive techniques. Following neurological plateau of the injury, which is usually between 6 - 12 months in the complete spinal cord injury, there are a number of reconstructive surgery options available to further improve upper limb function. This module will provide a guideline for the management of the tetraplegic upper limb, describe rehabilitation principles to develop a function hand. Common surgical reconstruction and other interventions will also be reviewed.  

Function and Management According to Neurological Level

The limitations experienced following spinal cord injury are dependent upon the severity and level of injury. While individuals with the same motor level of injury, assessed by the ICNSCI, will have similar muscles innervated, how they use these muscles is dependent on a number of factors such as age, body composition, completeness of spinal cord injury, other injuries and motor planning.  This makes describing expected functional capacity of a specific level difficult, however publications there are clinical practice guidelines published at outline the expected skills and outcomes for each significant level of spinal cord injury.  It is therefore important that a thorough examination of the upper limb with regarding to muscle strength, sensation and function is performed.  

Tenodesis Function

Tenodesis function occurs when the wrist is extended the fingers and thumb flex into the palm (Fig 1a) and then when the wrist is flexed the fingers and thumb open (Fig 1b).  This function is used to facilitate grasp in people with tetraplegia who have wrist extension against gravity but no active finger function (C6 Motor Level). It is critical to gain tenodesis function to enable task performance.  

Development of Tenodesis Function

Tenodesis function is fully dependent upon active wrist extension against gravity however, the process of development of tenodesis function is not fully understood.  While SCI is commonly considered a condition of the central nervous system because of the damage to the upper motor neurons, it is not uncommon for concurrent lower motor neuron damage to occur at the level of the injury.  Recent research demonstrates lower motor neuron damage at the level of the injury of finger extensors to be a strong predictor for development of tenodesis function.

Development of tenodesis function can be facilitated by:

• Constant monitoring of the hand and promoting correct tension in muscles and reducing hypertension from spasticity that may impact the balance and function of the hand.
• Prevention of overstretching of the finger flexors in both passive movements performed by the therapist, and functional activities such as propping on extended wrists or transferring.
• Prevention of oedema in the hand.
• Education of person with tetraplegia on tenodesis grasp, use of splints, self-stretches.  

Diverse splinting and taping strategies have been practiced, but no one strategy has yet proven to be superior in providing the desired tenodesis function. Failure to develop tenodesis function generally results in a less functional hand. One of the common presentations is the intrinsic minus (claw hand) (Figure 2).  

Management of the Upper Limb in the Sub Acute Phase 

It is accepted that the central nervous system is capable of reorganization, especially in the incomplete SCI because there is largely intact local spinal cord circuitry and some partially interconnected fibres.¹⁸ Within spinal cord injury, reorganization is thought to occur at two levels

1) in pre-existing circuits by synaptic plasticity or

2) in new circuits through sprouting or anatomical reorganization (anatomical plasticity).¹⁸

Traditional approaches to improving arm and hand function in people with tetraplegia generally is

1) strengthening of innervated muscles,

2) education of compensatory or substitution strategies and movement patterns and

3) translation into daily activities.

As soon as possible individuals should be encouraged and trained to use their hands in daily activities to recapture control over their life. The fundamental concept of motor learning is the assumption that practice of task-specific movements causes plastic changes in the central nervous system and that increased frequency and duration of training are associated to improvements in performance.¹⁹ There are several principles underlying the facilitation of neural plasticity and functional recovery such as intense activity and repeated practice.  

Strengthening of Remaining Innervated Muscles

Strengthening of the proximal muscles of the upper limb provides stability that makes arm and hand function possible.  The principles of strengthening are the same as for the able-bodied population; progressive increases in resistance aiming to increase muscle strength of innervated muscles.²⁰ Fatigue must be addressed when strengthening partially innervated muscles  as the muscle requires longer recovery time than a fully innervated muscle. FES can be used for treatment to strengthen weak muscles, improve hand posture/tenodesis, and guiding motor relearning.²¹ Studies using massed practice and/or FES have demonstrated potential for both neural and functional improvements in people with tetraplegia.^22,23

Education of Movement Patterns

In order to complete daily activities, the person with tetraplegia has to relearn many movement patterns. Essential to this his learning how to move and position their upper limb despite lack of critical functions such as elbow extension, finger and thumb movement. Compensatory strategies are movement patterns resulting from the adaptation of remaining muscles. An example of this is a person with tetraplegia learning to externally rotate the shoulder lifting the arm above the head to allow for the elbow to remain straight compensating for loss of elbow extension. In contrast, substitution is where functions are replaced or substituted by orthoses or assistive devices e.g. use of a universal cuff to hold eating utensils, typing peg (figure XX).

Compensatory Strategies

In the initial stage of rehabilitation, the person with spinal cord injury is unable to perform common tasks due to lack of skills. The learning process has similarities to an able-bodied person learning an unfamiliar sport, thus motor skill learning is a useful treatment technique in rehabilitation. Effective motor task training should be well structured, intense and incorporate practice that is task and context specific.²⁴  Feedback of the motor performance is essential to ensure correct motor patterns are reinforced. Complex tasks can be broken down in smaller sub-tasks and trained individually in a similar but simpler approach, before putting it all together.²⁵

Despite lack of active grip in the hand, those with active wrist extension are able to perform several compensatory strategies, such as tenodesis grasp, and can develop great skills in daily activities.²⁶ A well-balanced tenodesis function facilitates the opportunity for several adapted grips (figure XX). 

Measurement of Upper Limb Function 

Currently there is no international consensus on what measures to use for tetraplegic upper limb function.²⁷  The use of the International Classification of Functioning, Disability and Health (ICF) established by the World Health Organisation can assist in ensuring that measurement encompasses all domains of functioning and provide a common language of describing an individual functioning following illness or accident.²⁸  To provide a complete picture of an individual’s functioning use of multiple measures that encompass the three domains of the ICF are recommended.  Commonly used measures are detailed in below and described fully in Sinnott et al (2016).²⁹  International efforts are currently underway to establish consensus on standardising key body functions and structure measures such as muscle strength testing, and grip and pinch dynamometry.³⁰

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