Spinal muscular atrophy (SMA) is a hereditary neuromuscular disease caused by homozygous deletion or mutation of the SMN1 gene (chromosome 5q), leading to degeneration of the anterior horn cells of the spinal cord. Motor neurons are progressively lost, causing lower motor neuron weakness that affects proximal muscles preferentially and is non-progressive in type (each type describes a severity spectrum, not a progressive course within a type in most cases).
SMA Types and Ambulatory Status
- SMA type 1 (Werdnig-Hoffmann, severe): Onset before 6 months; cannot sit unsupported; natural history: median survival below 2 years without treatment. Gene therapy (onasemnogene abeparvovec, zolgensma) has transformed outcomes but most type 1 patients without treatment are non-ambulatory
- SMA type 2 (intermediate): Onset 6-18 months; can sit but typically cannot walk independently. Some patients walk with substantial orthopaedic support
- SMA type 3 (Kugelberg-Welander, mild): Onset after 18 months; can walk independently. Many type 3 patients remain ambulatory into adulthood, though walking capacity varies from near-normal to significantly impaired. THIS is the primary group relevant to walking cane use
- SMA type 4 (adult onset): Symptoms begin in adulthood; typically mild; walking maintained for decades
Disease-Modifying Treatments and Walking
Three approved treatments have transformed SMA outcomes:
- Nusinersen (Spinraza): Intrathecal antisense oligonucleotide; approved for all ages
- Onasemnogene abeparvovec (Zolgensma): Gene therapy; approved for children under approximately 21kg
- Risdiplam (Evrysdi): Oral SMN2 splicing modifier; approved for all ages
Treatment can improve or stabilise motor function. In previously non-ambulatory type 2 patients treated early, walking may be achieved. In type 3 patients, treatment may maintain or improve walking capacity. Cane need should be reassessed regularly in patients on treatment.
Walking Cane in SMA Type 3 and 4 Adults
SMA type 3 adults who are ambulatory have proximal lower limb weakness (hip flexors, quadriceps) that creates specific walking challenges:
- Difficulty rising from chairs and climbing stairs (quadriceps weakness)
- Trendelenburg gait from gluteal weakness
- Fatigue limiting walking endurance
- Falls risk on uneven terrain
A walking cane provides balance supplement and partially compensates for proximal weakness during community walking.
SMA Type and Walking Aid
| SMA Type | Typical Ambulatory Status | Walking Aid Role |
|---|---|---|
| Type 1 (untreated) | Non-ambulatory | Single cane not relevant |
| Type 1 (treated, improving) | Variable; some achieve walking | Based on achieved function; PT-guided |
| Type 2 | Non-ambulatory (some with support) | Forearm crutches or walker if walking achieved |
| Type 3 | Ambulatory; may decline over time | Single cane for balance; progression to crutches |
| Type 4 | Ambulatory; mild weakness | Single cane for terrain and fall prevention |
Explore the DaiWalk cane collection. Related: Walking Cane for Muscular Dystrophy | Walking Cane for Myasthenia Gravis
