Main mimics of MND based on experience of approximately 1000 patients seen in a tertiary referral clinic, and with the key clue to alternative diagnosis listed
| Predominant signs | Mimic disorder | Key clues |
|---|---|---|
| LMN | Benign fasciculations | No weakness |
| Multifocal motor neuropathy with conduction block | Weakness greater than wasting and predilection for finger extensors, slowly progressive | |
| Neuralgic amyotrophy | Severe pain at onset and arrest of progression | |
| Kennedy's syndrome (spinobulbar muscular atrophy) | Very slow progression with gynaecomastia, and often prominent chin fasciculations | |
| Motor-predominant CIDP | Symmetrical, fluctuating, mild sensory features, slowed conduction velocity | |
| Inclusion body myositis | Slowly progressive, predilection for quadriceps and medial forearms especially with serum creatine kinase >1000 IU/l | |
| UMN | Hereditary spastic paraparesis | Younger-onset, slowly progressive, minimal upper limb involvement, especially with family history |
| Primary progressive multiple sclerosis | Slowly progressive, often with sensory features, especially where there is possible MRI evidence of demyelination and positive CSF oligoclonal bands | |
| Mixed | Cervical myeloradiculopathy | Prominent neck pain especially with sphincter involvement. May be pure motor |
CIDP, chronic inflammatory demyelinating polyradiculoneuropathy; CSF, cerebrospinal fluid; LMN, lower motor neurone; MND, motor neurone disease; UMN, upper motor neurone.