Occurrence of excessive sweating during sleep.

Terminal broadening of the fingers (distal phalanges of the fingers).

The presence of an unusually high plantar arch. Also called high instep, pes cavus refers to a distinctly hollow form of the sole of the foot when it is bearing weight.

Inability to elicit tendon reflexes in the lower limbs.

Weakness of the muscles responsible for dorsiflexion of the foot, that is, of the movement of the toes towards the shin. The foot dorsiflexors include the tibialis anterior, the extensor hallucis longus, the extensor digitorum longus, and the peroneus tertius muscles.

Inability to elicit tendon reflexes in the upper limbs.

Difficulty in swallowing.

Fasciculations are observed as small, local, involuntary muscle contractions (twitching) visible under the skin. Fasciculations result from increased irritability of an axon (which in turn is often a manifestation of disease of a motor neuron). This leads to sporadic discharges of all the muscle fibers controlled by the axon in isolation from other motor units.

An unintentional, oscillating to-and-fro muscle movement about a joint axis.

Migraine is the most common type of chronic, episodic headache, as summarized by Featherstone (1985). One locus for migraine with or without aura (MGR1) has been identified on chromosome 4q24. Other loci for migraine have been identified on 6p21.1-p12.2 (MGR3; 607498), 14q21.2-q22.3 (MGR4; 607501), 19p13 (MGR5; 607508), 1q31 (MGR6; 607516), 15q11-q13 (MGR7; 609179), 5q21 (with or without aura, MGR8, 609570; with aura, MGR9, 609670), 17p13 (MGR10; 610208), 18q12 (MGR11; 610209), 10q22-q23 (MGR12; 611706), and the X chromosome (MGR2; 300125). Mutation in the KCNK18 gene (613655) on chromosome 10q25 causes migraine with aura (MGR13; 613656). A subtype of autosomal dominant migraine with aura (MA), familial hemiplegic migraine (FHM; see 141500), is caused by mutation in the CACNA1A gene (601011) on chromosome 19p13 (FHM1; 141500), by mutation in the ATP1A2 gene (182340) on chromosome 1q21 (FHM2; 602481), or by mutation in the SCN1A gene (182389) on chromosome 2q24 (FHM3; 609634). Another locus for FHM has been mapped to chromosome 1q31 (FHM4; see 607516). There is evidence that a polymorphism in the estrogen receptor gene (ESR1; 133430.0005) and a polymorphism in the TNF gene (191160.0004) may confer susceptibility to migraine. A polymorphism in the endothelin receptor type A gene (EDNRA; 131243.0001) may confer resistance to migraine.

A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months.

Reduced ability to perceive painful stimuli.

A decrease in the ability to perceive vibration in the distal portions of the limbs.

Reduced ability to walk in a straight line while placing the feet heel to toe.

A reduced ability to discriminate between different temperatures.

Irregular, small-amplitude myoclonic movements of the hands and/or fingers on keeping outstretched posture (jerky postural tremor). Polyminimyoclonus is stimulus-sensitive and accentuated during voluntary movements. A cortical origin can be demonstrated by back-averaging techniques, and somatosensory evoked potentials (SSEPs) are sometimes giant.

Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.

The presence of an abnormal lateral curvature of the spine.

Reduced strength of the musculature of the distal extremities.

An abnormal curvature of the spine in both a coronal (lateral) and sagittal (back-to-front) plane.

An abnormality in which the nuclei of sarcomeres take on an abnormally central localization (or in which this feature is found in an increased proportion of muscle cells).

Atrophy of the intrinsic muscle groups of the hand, comprising the thenar and hypothenar muscles; the interossei muscles; and the lumbrical muscles.

A lack of strength in the triceps muscle, which normally is responsible for extending (straightening) the elbow and mediating certain shoulder movements.

Stridor is a high pitched sound resulting from turbulent air flow in the upper airway.

An abnormal accumulation of fluid beneath the skin, or in one or more cavities of the body.

Decreased strength of the vocal folds.