Use of Modalities in Upper Limb Management in Tetraplegia

Original Editor - Ewa Jaraczewska

Top Contributors - Ewa Jaraczewska, Jess Bell and Tarina van der Stockt  

Introduction

There are a wide range of therapeutic modalities to help rehabilitate upper limb function in individuals with tetraplegia. This article overviews the most commonly used modalities for clients with upper and lower tetraplegia and the application will depend on the scope of practice of each professional. The description below is useful to understand what other professions might utilise as part of the multidisciplinary team management of a person with tetraplegia.

Vibration

Muscle vibration is a technique that can potentially reduce muscle tone and spasticity in individuals with spinal cord injury. Direct effects of muscle vibration include increased corticospinal excitability and inhibition of neuronal activity in the antagonistic muscle.

Focal vibration as a modality in spinal cord injury facilitates a contraction of the agonist muscle. For example, when a vibratory stimuli at 80 Hz is applied to triceps brachii, an isometric contraction can be induced.

Motor effects achieved through muscle vibration:

1. Sustained contraction of the vibrated muscle via tonic vibration reflex
2. Depression of the motor neurons innervating the antagonistic muscles via reciprocal inhibition or antagonistic inhibition
3. Suppression of the monosynaptic stretch reflexes of the vibrated muscle while vibration is applied

The sustained effect of vibration is still under investigation. According to Laessøe et al., lower limb spasticity in a person with a spinal cord injury can be reduced for up to 3 hours following vibratory stimulation at 100 Hz.

Two different vibration frequencies can be chosen and applied directly to the muscle or tendon. These are high-frequency and low-frequency vibration.

High-frequency vibration

• Frequency of 100-200 Hz
• Amplitude of 1-2 mA
• Facilitates muscle contraction through a tonic vibration reflex
• The effect is brief after application

Low-frequency vibration

• 5-50 Hz
• Produces an inhibitory effect on the muscle through the activations of:
  • spindle secondary endings, which are responsible for "signalling slow and maintained changes in the relative position of bodily segments", therefore contributing to position sense, postural control and static limb positioning
  • Golgi tendon organs

General precautions

• Heat generation at the point of application when high amplitude vibration is used can cause skin damage
• Unstable health conditions (unstable spine, fractures)

Potential concerns related to the use of vibration therapy

• Increased risk of thrombosis
• Risk of tissue damage from acute or severe oedema
• Increased cardiac issues
• Dislodgement of a thrombus
• Increased damage from peripheral vascular disease
• Effects on spinal stimulators
• Skin injury from friction

You can read more about self-applied vibration here.

Surface Stimulation

Two of the most commonly used forms of surface stimulation are:

• Transcutaneous Electrical Nerve Stimulation (TENS)
• Functional Electrical Stimulation (FES)

Transcutaneous Electrical Nerve Stimulation (TENS)

TENS is a "surface applied neuromodulation system that has been utilized in the treatment of various types of chronic pain, including noninvasive neuropathic pain relief." TENS stimulates sensory A-beta fibres in chronic pain management. As a result, pain signals transmitted via A-delta and C-nociceptive fibres are blocked. TENS enhances presynaptic inhibition in spasticity management following spinal cord injury and "induces short-term neuroplasticity by increasing the strength of reciprocal Ia inhibition" between antagonistic (flexors and extensors) muscles.

The points below summarise the mechanisms of TENS:

• TENS activates sensory nerves
• Sensory nerves activate inhibitory interneurons
• Spastic muscle activity is inhibited
• May involve the stimulation of large-diameter afferent fibres

Goals:

1. To reduce spasticity
2. To alleviate pain
3. To reduce muscle fatigue

Treatment Protocol Examples

Spasticity management:

• Stimulation over the trajectory of the nerve
• High frequency of 50–150 Hz
• Most studies do not specify the intensity used
  • Fernández-Tenorio et al. note that research studies commonly use vague "expressions of perceived sensation", such as "below the motor threshold" or "bearable pain threshold" etc
• The stimulation in the study by Fernández-Tenorio et al. tended to cause a tolerable tingling sensation, but not a pain sensation

Neuropathic pain management:

• High frequency of 80 Hz
• Each session lasts for 45 minutes
• Two sessions per day for eight weeks
• Adverse effects can be present: rash and local tingling sensation
• Possibility of relapse of neuropathic pain

Functional Electrical Stimulation

In functional electrical stimulation (FES), an electrical stimuli is applied to paralysed nerves or muscles. This induces a muscular contraction and enables an individual with spinal cord injury to complete a functional task. FES is believed to "support the rewiring and regeneration of damaged synaptic connections".

FES can produce the following metabolic benefits:

• Increase in lean muscle mass
• Increase in capillary number
• Decrease in adipose tissue

Other benefits include lowering blood glucose and insulin levels, improvement in muscle size, strength, and composition, improved fatigue resistance and oxidative capacities, and proportional increases in fibre area and capillary number.

Goals:

1. To prevent upper limb muscle atrophy
2. To increase muscle strength
3. To increase endurance
4. To improve cardiovascular fitness

In persons with tetraplegia, FES can be used to:

• Replace function (as an orthotic device)
• Retrain function (as a therapeutic device)

Replacing Function

• Specific movement facilitation (neuroprosthesis)
• A neuroprosthesis consists of an electrical stimulator, stimulation-delivering electrodes, sensors for the user or automatic control of the stimulation, and an orthosis that provides additional assistance to perform the desired movement.
  • The electrical stimulator generates the electrical discharges. It produces muscle contraction.
  • Electrodes connect the external circuitry and the tissue. They are transcutaneous or implantable.
  • Sensors provide biofeedback for the neuroprosthesis. The maximum functionality of a neuroprosthesis depends on the sensors.
  • The orthosis provides assistance to perform the desired movement. It prevents muscle fatigue and helps patients conserve energy.

Examples of neuroprostheses designed to improve the ability to grasp and manipulate objects include:

• IST-12
• NESS H200
• Bionic Glove
• HandEstim Wireless Hand Stimulator
• MyndMove stimulator

Retraining Function

• Short-term treatment modality
• The patient is expected to regain voluntary function
• Kapadia et al. describe a protocol for transcutaneous FES to retrain reaching and grasping in individuals with spinal cord injury:
  • The upper extremity retraining programme is "designed based on the level and extent of the injury"
  • An individual with upper tetraplegia will start by retraining proximal function followed by distal function
  • An individual with lower tetraplegia (where proximal function may be preserved) can retrain distal function from the beginning
  • An individual with little to no voluntary movement at the wrist and fingers can perform simple tasks while FES is applied
  • The number of repetitions is based on the individual's strength and endurance
  • In a one hour session, the patient performs 30–45 minutes of activities of daily living with FES
  • The following parameters are used: balanced, biphasic, current-regulated electrical pulse; pulse amplitude from 8-50 mA; pulse width 250 μs; and pulse frequency 40 Hz
  • During the session, the therapist can guide the patient's hand to make the movement functional
  • A typical FES session lasts for 45–60 minutes, and is performed 3-5 days a week, for 8-16 weeks, for a total of around 40 sessions

Resources

• Marquez-Chin C, Popovic MR. Functional electrical stimulation therapy for restoration of motor function after spinal cord injury and stroke: a review. Biomed Eng Online. 2020 May 24;19(1):34.
• Ragnarsson KT. Functional electrical stimulation after spinal cord injury: current use, therapeutic effects and future directions. Spinal Cord. 2008 Apr;46(4):255-74.