The entire wall around the sac is an extension of the central canal and is formed of medullary substance. The skin which covers the sac is at times greatly thinned by pressure, but always shows its histological layers. It is often deeply pigmented and covered with hair. There arc no nerves ending in the sac itself, but they lie on its anterior aspect and pass on to the vertebral apertures—a matter of importance in the surgical treatment. This degree of deformity (Fig. 6) is not often accom panied by paralysis, but when this is present it depends on the seat of the lesion and corresponds to the segmentary arrangement of the centres of the spinal cord.
.1. Spinal M eningocele. —In very rare eases the soft cerebral menin ges are alone prolapsed. In these eases the wall of the growth consists only of these and is nowhere adherent to t he spinal marrow. The latter, with its nerve loops, frequently lies freely exposed.
5. Spina Bifida Occulta (Bayer, Kirmisson).—Fissures and de fects are not uncommon occurrences at the lower cud of the vertebral column over which the skin passes without the formation of tumors. The deep pigmentation, hair tufts, mcvi, small lipomata and fibromata testify to former disturbances and healed conditions (Bayer).
The defects may be very extensive. I know of two such eases. In one there was a rudimentary development of the entire sacrum and two lower lumbar vertebra'. A partial paralysis of the lower extremities, bladder, and rectum led to the discovery, and the radiographic demon stration showed the osseous defect over which the skin passed in a perfectly normal manner. In the second ease the paralysis of the bladder and rectum caused the discovery. The fissure in the sacrum lay a little lower than in the preceding case, so that the extremities were not involved.
It is interesting and characteristic for the early origin of the defor mity that the peripheral paralysis from the segments of the cord corre sponds exactly to the fissures in the vertebra', while later in life the segmentary arrangement of the vertebra' and those of the spinal cord no longer correspond in normal conditions, the growth of the spinal cord being arrested and its segments lying higher than the corresponding vertebra.
Bayer claims that tumors of the lower sacral and coccygeal regions which likewise had their origin in the displacement of the blastoderm at a very early period of development can easily be mistaken for spina bifida.
As to anatomical location, the upper and lower ends of the vertebral column are the more favorable sites, since the medullary canal closes last at these places. The seat of the disturbance can be easily located
according to the known segmentary arrangement from the way the paralysis spreads.
Examination.—It is sometimes possible to obtain information as to the nature of the growth by inspection. In other eases this is difficult and sometimes it may be impossible to distinguish the various forms of spina bifida. Cases with exposed spinal cord and a pronounced medulla vascular zone at once point to fissure of the spinal column or myelo ineningoeele. While these eases are of little surgical interest, the cystic forms that are surrounded by skin and arc not complicated by paralysis command our greatest interest on account of their operative possibilities.
These tumors are of the same consistency as cerebral hernia. They vary in tension corresponding to the pressure of the fontanelles and are partly expressible. When the sacs are flaccid the vertebral contents can be palpated; sometimes the sacs are pedunculated. By transillumina tion it is possible to observe clerk cords, and sometimes the contents can be felt. (This points rather to a greater deformity of the spinal cord.) Light transparent contents, great expressibility, and absence of the cord point to a cystic distention of the cavity or of the membrane of the•spinal cord. (See Zappert.) The prognosis varies according to the degree of the deformity. The most pronounced cases develop rapidly and terminate fatally because of infection and of the extensive paralysis of the vegetative organs. The well-covered cystic forms show few symptoms. The difficulty is that these growths have a tendency to marked distention owing to the weight of the body resting upon them. At the same time the wall becomes extremely thin, so that in any case this deformity is always a constant danger to life.
The treatment can rationally be only operative, and the following points will have to be determined: 1. Which cases are operable? 2. Was hydrocephalus a causative factor? 3. What operative and palliative measures arc possible? 4. What methods should be selected? The first question must be answered by humanitarian considerations. I entirely agree with Bayer that children with extensive paralysis should be allowed to die without interference. Although there is little proba bility of an operation being successful, yet the "misfortune" may happen that an operated child of this class will live and become a torment to itself and to everybody with whom it comes in contact. I consider it quite impossible for paralysis to be cured by operation.