Precision assessment to guide treatment planning

At GC Rehab, diagnostic nerve blocks (DNBs) are used to help assess and manage spasticity in patients with neurological conditions such as stroke, cerebral palsy, acquired brain injury, spinal cord injury, multiple sclerosis, and other upper motor neuron disorders.

A diagnostic nerve block is a temporary injection of local anaesthetic around a specific motor nerve or nerve branch. The aim is to temporarily reduce overactivity in selected muscles so we can better understand how much of a patient’s movement difficulty is due to spasticity versus weakness, contracture, dystonia, pain, or biomechanical changes.

This can help guide decisions regarding:

• Botulinum toxin injections
• Cryoneurolysis
• Orthopaedic surgery
• Therapy planning
• Splinting or casting
• Goal setting and functional rehabilitation

Why are diagnostic nerve blocks useful?

Spasticity management is highly individualised. Sometimes it can be difficult to predict whether weakening a muscle will improve or worsen function.

Diagnostic nerve blocks allow us to “test drive” the effect of reducing tone before committing to a longer-lasting intervention.

Examples of questions a DNB may help answer:

• Will reducing calf spasticity improve walking?
• Is finger flexor spasticity limiting hand opening?
• Will reducing shoulder internal rotation improve hygiene or dressing?
• Is a muscle truly spastic, or is stiffness mainly due to contracture?
• Would cryoneurolysis or botulinum toxin likely help?

The temporary nature of the block allows the rehabilitation team, patient, and carers to assess potential benefits in real time.

How is the procedure performed?

The procedure is typically performed in the clinic using:

• Ultrasound guidance
• Electrical stimulation guidance
• Sterile technique (ANTT)

A small amount of local anaesthetic is injected around the selected nerve or motor branch.

Common targets include:

• Musculocutaneous nerve
• Median nerve
• Ulnar nerve
• Tibial nerve branches
• Obturator nerve
• Motor branches to muscles contributing to focal spasticity

The procedure usually takes approximately 30–90 minutes depending on the complexity and number of targets assessed.

What happens after the injection?

The effects of the local anaesthetic are temporary and usually begin within minutes.

Patients may notice:

• Reduced stiffness
• Easier passive movement
• Improved limb positioning
• Changes in walking or hand function
• Temporary weakness in the targeted muscles

The effects generally last several hours.

During this time, assessment may be performed by:

• The rehabilitation physician
• Physiotherapists
• Occupational therapists
• The patient and family/carers

This helps determine whether a more durable intervention may be appropriate.

What conditions can diagnostic nerve blocks help assess?

Diagnostic nerve blocks may be useful in:

• Stroke-related spasticity
• Cerebral palsy
• Traumatic brain injury
• Spinal cord injury
• Multiple sclerosis
• Hereditary neurological disorders
• Dystonia with mixed tone patterns
• Painful muscle overactivity
• Complex upper limb or lower limb posturing

Are diagnostic nerve blocks painful?

Most patients tolerate the procedure well.

You may feel:

• A brief sting from the needle
• Muscle twitching if electrical stimulation is used
• Temporary heaviness or weakness afterwards

Sedation is generally not required for standard clinic-based procedures.

Are there risks?

Diagnostic nerve blocks are generally considered low risk when performed under ultrasound guidance by experienced clinicians.

Potential risks include:

• Temporary weakness
• Bruising
• Bleeding
• Infection
• Numbness
• Falls risk immediately after lower limb blocks
• Allergic reaction (rare)

Patients are usually advised to avoid strenuous activity immediately afterwards until the effects of the local anaesthetic wear off.

What happens next?

Following the assessment, a management plan may include:

• Botulinum toxin injections
• Cryoneurolysis
• Therapy-based rehabilitation
• Orthotic management
• Stretching and positioning programs
• Referral for surgical opinion where appropriate

A detailed report can also be provided to the treating therapy team and referrers.

Referrals

Referrals are welcome from:

• General Practitioners
• Rehabilitation physicians
• Neurologists
• Orthopaedic surgeons
• Allied health practitioners

For referrals or enquiries, please contact GC Rehab.