Surgery of Spinal Column

Sometimes a tuberculous abscess forms within the neural canal, extends backwards from the diseased vertebrae, and presses on the cord. Happily most of these patients recover the function of their limbs when perfectly immobilised ; laminectomy does not give the good results which one might theoretically expect from it.

Pain.

Much can be done for sufferers from agonising pain by judicious spinal surgery. The chief indications for operation are neuralgia of the body or limbs, often the sequelae of amputations or of herpes zoster, the agonising pains of spinal syphilis, and hopeless malignant growths. The usual operation heretofore has been section of posterior nerve roots just before they enter the spinal cord. The exposure is the same as for spinal tumours. The results of root sections have been inconsistent, and the operation is being replaced by section of the pain-carrying fibres in the cord itself (Spiller). This tract is the anterior spino-thalamic and lies just sufficiently far away from the motor pathway to the limbs (pyramidal tract) for its division to be effected without inflicting paralysis on the sufferer. As the pain fibres cross in the cord, the tract of the opposite side to that on which the pain is felt is the one to be cut, and of course at,a point cephalad to the site of the pain. A cut 2.5 to 3.omm. deep is made into the antero-lateral aspect of the cord. A very fine and sharp knife is required and the operation must be most delicately and precisely performed. Bril liant results have generally followed, but it is too early to say what the late effects are.

Spinal Puncture.

No account of modern spinal surgery can omit some reference to the extended usefulness which is being made of lumbar puncture (puncture into the subarachnoid space and withdrawal of a specimen of cerebro-spinal fluid). Our knowl edge of the changing chemistry of that fluid in disease conditions is still growing. When a tumour or the like grows in relation to the spinal cord it causes a block in the subarachnoid space, either by its own bulk or by compressing the membranes against one another should it be extra-dural. The cerebro-spinal fluid distal (caudal) to the obstruction is dammed back, for it is chiefly ab sorbed within the skull and thither it can not now return. A rise in albuminous content and a yellow tinge, xanthochromatosis (Froin's syndrome), are the results. This is of great diagnostic importance. Queckenstedt's test also makes use of the block, for when a normal person's jugular veins are compressed the conse quent rise of intracranial venous pressure is transmitted to the cerebro-spinal fluid as a whole and can be measured by a mano meter attached to a lumbar-puncture needle. If a tumour blocks

the spinal canal the manometer records no change or modified changes only. This is most valuable in differentiating between the degenerative and compression groups of paralysis of the lower limbs. Lastly, Lipiodol, a heavy, opaque substance which when introduced into the cerebro-spinal fluid above the tumour sinks down through it to rest on the tumour, is proving most useful. It is a 4o% solution of inert iodine in poppy-seed oil and is quite opaque to X-Rays so that the precise position and often the shape of the upper end of the tumour becomes definitely recognisable.

BIBLIoGRApHY.—Armour, "The Surgery of the Spinal Cord and its Membranes," Lancet. 1927, I. 423 ; Ayer, "Spinal subarachnoid block as determined by combined cistern and lumbar puncture," Arch. Neurol. Psychiat. 1922, Vii. 38 ; Elsberg, Tumours of Spinal Cord (London, 1925) ; Frazier, "Section of the antero-lateral columns of the spinal cord for the relief of pain," Arch. Neurol, Psychiat, 192o, iv., 137 ; Foerster, Die Leitungsbahnen des Schmerzgefiihls and die Chi rurgische Behandlung der Schmerzzustande (Berlin, 1927) ; Jefferson, "Spinal Injuries," Proc. Roy. Soc. Med., 1928, xxi., 2 1 . (G. J.) SPINAL CORD, in anatomy, that part of the central nervous system in man which lies in the spinal canal formed by the ver tebrae, and reaches from the foramen magnum to the lower margin of the first lumbar verte bra. It is about i8in. long, and only occupies the upper two thirds of the spinal canal. The cord is protected by the same three membranes which surround the brain. Outside is the dura mater, which differs from that of the brain in not forming a periosteum to the bones, in sending no processes inward, and in having no blood sinuses enclosed within its walls ; it is the continuation of only the inner layer of the dura mater of the skull. Inside the dura mater is the arachnoid, which is delicate and transparent, while between the two lies the sub dural space, which reaches down to the second or third sacral vertebra. The pia mater is the innermost covering, and is closely applied to the surface of the cord into the substance of which it sends processes. Between it and the arachnoid is the sub-arachnoid space, which contains the cerebrospinal fluid. Across this space, on each side of the cord, run a series of processes of the pia mater arranged like the teeth of a saw; by their apices they are attached to the dura mater, while their bases are continuous with the pia mater surrounding the cord. These ligaments, each consisting of twenty-one teeth, are the ligamenta denticulata, and by them the spinal cord is moored in the middle of the cerebrospinal fluid.