Knowra Hereditary spastic paraplegia Hereditary spastic paraplegia Hereditary spastic paraplegia is a group of inherited neurological disorders causing progressive stiffness and weakness in the legs. It results from dysfunction of long motor pathways in the spinal cord.
Corticospinal tract : A descending motor pathway that carries signals from the cerebral cortex to spinal motor circuits. Its long axons are especially vulnerable in many forms of the disorder.
Spasticity : Increased muscle tone that worsens with rapid stretching and reflects an upper motor neuron lesion. It is the characteristic stiffness behind the disorder’s name.
Neurological examination : A clinical assessment of nervous-system function using tests of strength, reflexes, sensation, coordination, and gait. Leg tone, reflexes, strength, and walking help characterize the motor-pathway pattern.
Primary lateral sclerosis : A rare adult-onset motor neuron disorder causing progressive upper motor neuron dysfunction without a known inherited cause in most cases. It can resemble a pure motor form but is generally diagnosed by its clinical course and exclusion of alternatives.
Incomplete penetrance : A genetic pattern in which some people with a disease-associated variant do not develop recognizable symptoms. Some families show carriers who remain unaffected, complicating risk estimates and diagnosis.
Axonal transport : The movement of proteins, organelles, and other materials along neuronal axons. Impaired transport can deprive long corticospinal axons of materials needed for maintenance.
Paraparesis : Weakness affecting both legs, ranging from mild loss of strength to severe impairment. Progressive bilateral leg weakness is the other core feature.
Magnetic resonance imaging : An imaging method that uses magnetic fields and radio waves to produce detailed pictures of the body. Brain and spinal imaging can exclude structural mimics and identify associated abnormalities.
Amyotrophic lateral sclerosis : A progressive motor neuron disease affecting upper and lower motor neurons, usually causing worsening weakness and muscle wasting. Lower motor neuron signs and broader progression distinguish it from many uncomplicated hereditary cases.
Variable expressivity : Differences in the severity or features of a trait among people with the same genetic variant. Even within one family, age of onset and disability can differ substantially.
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