Motor Neurone Disease EMG in Sydney
Specialist multi-region EMG following El Escorial and Awaji criteria — Dr Ron Granot, FRACP, Bondi Junction.
Book Your TestThe Role of EMG in MND Diagnosis
Motor neurone disease (MND), also known as amyotrophic lateral sclerosis (ALS), is a progressive disorder of the motor neurones — the nerve cells that control voluntary muscles. Diagnosis is fundamentally clinical, but needle electromyography (EMG) plays a central role: it demonstrates the characteristic pattern of widespread lower motor neurone involvement that defines the condition.
What is Multi-Region EMG?
The diagnostic criteria for MND (El Escorial, revised El Escorial, and the more recent Awaji criteria) require evidence of lower motor neurone involvement in at least two of four body regions. A comprehensive EMG samples muscles representing each region to demonstrate the widespread distribution that distinguishes MND from focal disorders.
Bulbar Region
Tongue, masseter, or facial muscles. Sampled selectively when bulbar symptoms (speech, swallowing) are present or to demonstrate subclinical involvement.
Cervical Region
Upper limb muscles supplied by C5–T1 nerve roots — typically biceps, deltoid, first dorsal interosseous, abductor pollicis brevis. Two roots from at least two different nerve distributions.
Thoracic Region
Paraspinal muscles or upper abdominal muscles. Often the earliest region to show subclinical denervation in lower-limb-onset MND.
Lumbosacral Region
Lower limb muscles supplied by L2–S1 — typically vastus lateralis, tibialis anterior, gastrocnemius, peroneus longus. Two roots from at least two different nerve distributions.
The Electrodiagnostic Signature of MND
The findings supporting MND on EMG combine active (acute) and chronic denervation features in widespread distribution:
| Finding | What it represents |
|---|---|
| Fibrillation potentials | Active denervation — recently denervated muscle fibres firing spontaneously. |
| Positive sharp waves | Same significance as fibrillations — recent denervation. |
| Fasciculation potentials | Spontaneous firing of motor units. In MND, fasciculations of varying morphology and complexity. The Awaji criteria allow these to count as denervation evidence in the appropriate clinical context. |
| Large polyphasic motor unit action potentials | Chronic reinnervation — surviving motor neurones have sprouted to take over denervated muscle fibres, producing larger and more complex motor units. |
| Reduced recruitment | Fewer motor units firing at maximum effort because some have been lost. |
| Normal sensory NCS | Sensory studies should be normal — abnormal sensory findings suggest an alternative diagnosis. |
Excluding Mimics
Several conditions can produce features that resemble MND. Excluding these is a critical role of the electrodiagnostic study:
| Mimic | Why considered | Distinguishing test feature |
|---|---|---|
| Multifocal motor neuropathy | Asymmetric pure motor weakness with fasciculations | Conduction block on NCS. Treatable with IVIG. |
| Cervical myeloradiculopathy | Hand wasting + upper motor neurone signs in legs | MRI cervical spine. Sensory findings on NCS. |
| Inclusion body myositis | Wasting of forearm flexors and quadriceps | Myopathic motor units on EMG. Elevated CK. Muscle biopsy. |
| Benign fasciculation syndrome | Visible muscle twitching without weakness | No denervation potentials. No weakness or wasting on exam. No progression. |
| Kennedy's disease | Bulbar features and limb weakness | Genetic testing (androgen receptor CAG repeat). Sensory neuropathy on NCS. |
What to Expect at Your Test
Unhurried clinical assessment
Dr Granot reviews your history, the symptom timeline and any imaging or prior investigations. Time is taken to understand your concerns and what you have already been told.
Comprehensive nerve conduction studies
Motor and sensory studies in upper and lower limbs to exclude inflammatory or compressive neuropathy and confirm normal sensory function (a key feature of MND).
Multi-region needle EMG
Systematic sampling of muscles across bulbar, cervical, thoracic and lumbosacral regions — selected to satisfy Awaji-modified El Escorial criteria. Each muscle is sampled with care and minimal discomfort.
Honest, sensitive results discussion
Findings are explained in plain language at the conclusion of the test. Whether the result is consistent with MND, suggests an alternative diagnosis, or is non-diagnostic, the discussion is unhurried and clear. Onward referral to an MND clinic is coordinated where indicated.
Same-day report and direct referrer contact
A formal written report is sent to the referring doctor the same day. For diagnoses with significant implications, Dr Granot phones the referring doctor directly to discuss next steps.
Frequently Asked Questions
Specialist EMG Workup with Care & Continuity
Multi-region testing • Same-day discussion • Direct referrer contact
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