Paralysis of voluntary muscles means loss of contraction due to interruption of one or more motor pathways from the brain to the muscle fibers. Although the word paralysis is often used interchangeably to mean either complete or partial loss of muscle strength, it is preferable to use paralysis or plegia for complete or severe loss of muscle strength, and paresis for partial or slight loss. Motor paralysis results from deficits of the upper motor neurons (corticospinal, corticobulbar, or subcorticospinal). Motor paralysis is often accompanied by an impairment in the facility of movement.

Horner syndrome, resulting from unilateral paralysis of the cervical sympathetics, comprises the classic triad of unilateral ptosis, unilateral miosis with anisocoria, and ipsilateral facial anhidrosis. Iris heterochromia may also be present (Takanashi et al., 2003).

Inability to sweat on the same side of the face that is affected by ptosis and miosis. This is a feature of Horner syndrome.

An eye that is more deeply recessed into the plane of the face than is typical.

Heterochromia iridis is a difference in the color of the iris in the two eyes.

Horner syndrome, resulting from unilateral paralysis of the cervical sympathetics, comprises the classic triad of unilateral ptosis, unilateral miosis with anisocoria, and ipsilateral facial anhidrosis. Iris heterochromia may also be present (Takanashi et al., 2003).

Neurodevelopmental disorder with hypotonia and dysmorphic facies (NEDHYDF) is characterized by global developmental delay and hypotonia apparent from birth. Affected individuals have variably impaired intellectual development, often with speech delay and delayed walking. Seizures are generally not observed, although some patients may have single seizures or late-onset epilepsy. Most patients have prominent dysmorphic facial features. Additional features may include congenital cardiac defects (without arrhythmia), nonspecific renal anomalies, joint contractures or joint hyperextensibility, dry skin, and cryptorchidism. There is significant phenotypic variability in both the neurologic and extraneurologic manifestations (summary by Tan et al., 2022).