Neuromuscular Diseases, Ultrasound, and Image Analysis

Abstract

Since 1 year this male 45-year-old patient is not able to walk on his toes. In addition the heels of his shoes show an asymmetric wear pattern. His symptoms are so minor that he did not seek medical advice until the abnormalities were noticed when he had to be tested for a new driver’s license. After tests showed that he suffered from an isolated paresis of both tibial anterior muscles, his general practitioner made an MRI of the lumbar vertebra, thinking that his complaints could be related to a nerve entrapment in this region. The MRI was normal, but the blood level of creatine kinase (CK) was extremely high, indicating muscle cell damage. When the patient was sent to the neurologist, absent Achilles (ankle jerk) reflexes were found while his other reflexes were normal, indicating a peripheral problem. He had no sensory disturbances. Although the neurologist thinks that this patient may suffer from a distal myopathy, further investigations are needed to confirm this diagnosis.

Glossary

Attenuation

Gradual loss of intensity of a signal

Axial

Toward the central axis of the body

Caliper

Device used to measure distance between two points

Congenital

Existing from birth or even before

Creatine kinase

An enzyme important for energy storage and transport in the brain, muscles, eyes, and ears

Demyelinating

Leading to loss of the insulating myelin layer around nerves

Dopaminergic

Related to the neurotransmitter dopamine. Dopamine producing neurons in the substantia nigra are lost in Parkinson’s disease

Echogenicity

Ability to reflect a sound wave

Epineurium

Outermost layer of connective tissue surrounding a nerve

Fascicle

Larger bundle of nerve fibers

Fasciculations

Involuntary spontaneous contraction of fascicles, visible under the skin from the outside

Fibrillation

Spontaneous pathological muscle fiber contraction that cannot be observed under the skin from the outside

Fibrous

Containing fibers

Fractal

A geometric shape that repeats itself on different spatial scales

Immunoglobins

Antibodies

Longitudinal

Along the longest axis (of the muscle) or in parallel with the direction of movement (of waves)

Motor neuron

Neurons located in the central nervous system with long axons, controlling muscles

Myopathy

Disease of the muscles

Neurogenic

Originating from the nerves

Neuroma

Growth or tumor of nerve tissue

Neuropathy

Disease of the nerves

Neuroprotective

Protection of neurons from cell death or degeneration

Skewness

Measure of asymmetry of a distribution

Substantia nigra

Brain structure located in the midbrain

Tetraparesis

Paralysis in all limbs

Transducer

Device that transforms one form of energy into another: here electrical energy is transformed into sound energy

Transversal

Perpendicular to the longest axis (of the muscle) or perpendicular to the direction of movement (of waves)

Trendelenburg gait

Abnormal gait caused by weakness of hip muscles