The lesions affecting principally the gray matter of the cord are anterior poliomyelitis, syringomyelia, progressive muscular atrophy, and arthritic muscular atrophy.

Anterior Poliomyelitis

In anterior poliomyelitis or infantile paralysis the lesion is mainly in the anterior horn and is evidenced by a paralysis of the muscles involved, atrophy, and the abolishing of the reflexes. The deformities seen are secondary results of the paralysis.

Syringomyelia is an acquired enlargement of the central canal or the formation of new canals in the gray matter. It produces motor, sensory, and trophic disturbances which vary according to the part of the cord attacked.

Progressive Muscular Atrophy (Duchenne's Disease)

The atrophy begins most often in the hands and extends to other parts of the body. Then occurs an atrophy of the gray substance of the anterior horns which may extend to the brain; even the white substance of the direct and crossed pyramidal tracts may also show degeneration. There is a type in which there is a lack of demonstrable cord lesions. Among its various forms are those called pseudomuscular hypertrophy, progressive muscular dystrophies (Erb), and primitive progressive myopathies (Charcot).

Arthritic Muscular Atrophy

Disease of the joints often results in marked disturbance of the gray matter of the cord, which in turn is followed by muscular atrophy (Church: Church and Peterson, Nervous and Mental Diseases, page 38).

Lesions Affecting Principally The White Matter Of The Cord

The principal lesions affecting the white matter are lateral sclerosis, locomotor ataxia, combined posterolateral sclerosis, Friedreich's ataxia, and hereditary spastic paraplegia.

Lateral sclerosis, or spastic paraplegia, is almost unknown as a primary affection. It is a sclerosis of the pyramidal tracts. It occurs as a secondary degeneration, the result of cerebral disease, producing the spastic paraplegia of infants - Little's disease - and also follows transverse lesions of the spine from tumors, caries, fractures, etc.

Locomotor ataxia, or tabes dorsalis, when advanced may affect the entire portion of the cord between the posterior horns and the commissure, from the filum terminale to the medulla. It begins in Clarke's column (a group of cells in the posterior horn of the cord extending from the seventh cervical to the second lumbar nerves) and may involve the direct cerebellar tracts and Gowers's ascending anterolateral tracts and also the posterior nerve roots. It produces both motor and sensory disturbances as well as trophic changes.

Combined Posterolateral Sclerosis - (Ataxic Paraplegia Of Gowers)

This produces symptoms combining spastic paraplegia and locomotor ataxia. The following structures are affected: columns of Burdach, Goll, crossed pyramidal tract, direct pyramidal tract, and not always the ascending tract of Gowers.

Friedreich's ataxia (family or hereditary ataxia) is a progressive paralysis often appearing through many generations. There is a sclerosis of the columns of

Goll and Burdach, crossed pyramidal tract, Gowers's tract, direct cerebellar tract, Lissauer's tract, and often atrophy of the cells of Clarke's column. Hereditary Spastic Paraplegia. - This is a degeneration of the pyramidal tracts, columns of Goll and Burdach, and direct cerebellar tract. The disease has been traced through many generations.