Rare diseases · Sign or symptom
Upper motor neuron dysfunction
HP:0002493
What it means
A functional anomaly of the upper motor neuron. The upper motor neurons are neurons of the primary motor cortex which project to the brainstem and spinal chord via the corticonuclear, corticobulbar and corticospinal (pyramidal) tracts. They are involved in control of voluntary movements. Dysfunction leads to weakness, impairment of fine motor movements, spasticity, hyperreflexia and abnormal pyramidal signs.
A functional deficit of the tract that conveys nervous impulses from the motor cortex of the brain to the spinal cord. The corticospinal tract mediates discrete voluntary skilled movements. Clinical features of corticospinal tract dysfunction may include spasticity and weakness, particularly affecting the lower limbs, as well as hyperreflexia, clonus at the ankles and knees, and extensor plantar responses (Babinski response).
Rare diseases that can present with this35
Very common80–99%
6Common30–79%
15- 4H leukodystrophy
- Adult-onset autosomal dominant leukodystrophy
- Atypical pantothenate kinase-associated neurodegeneration
- Autosomal dominant Charcot-Marie-Tooth disease type 2Z
- Autosomal dominant spastic paraplegia type 10
- Autosomal dominant spastic paraplegia type 9B
- Fatty acid hydroxylase-associated neurodegeneration
- Late-infantile/juvenile Krabbe disease
- Leigh syndrome
- Leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome
- Machado-Joseph disease type 2
- Machado-Joseph disease type 3
- Spinocerebellar degeneration-corneal dystrophy syndrome
- Tremor-ataxia-central hypomyelination syndrome
- X-linked complicated spastic paraplegia type 1
Sometimes5–29%
13- Abetalipoproteinemia
- Acute transverse myelitis
- Autosomal recessive complex spastic paraplegia due to Kennedy pathway dysfunction
- Behavioral variant of frontotemporal dementia
- Cysticercosis
- Huntington disease-like syndrome due to C9ORF72 expansions
- Inclusion body myopathy with Paget disease of bone and frontotemporal dementia
- Kufor-Rakeb syndrome
and 5 more in this range
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions, and Orphanet separately records 1 disease where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Corticospinal tract dysfunction · Pyramidal tract dysfunction
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.