and about 10-12.5 cm. in length, armed with a stylet, is necessary. In recent years the writer has been using a sharp pointed nickeloid needle of about 18 or 20 gauge B & S, for puncture. For children a 7.5-8 cm. needle of about 20 gauge (B & S) and about 10 cm. long is necessary. For very stout and muscular individuals a needle at least 10-12.5 cm. long is necessary. The needle should always be

FIG. 5.-LUMBAR PUNCTURE: INTRODUCTION OF THE NEEDLE.

Note forefinger of left hand pointing to interspinous space. Needle being introduced perpendicular to skin and parallel to plane passing through spinal column.

guarded by a stylet, which serves not only to keep the lumen free until the subarachnoid space is reached, but can also be used to regulate the flow of spinal fluid. There are a number of special needles on the market designed for the purpose of facilitating the withdrawal of fluid slowly, measuring the pressure of the fluid and providing means of easily and quickly attaching an apparatus or syringe for the injection of therapeutic sera. The apparatus of I. Strauss 63 is one of the simplest and best of these. It is shown in Fig. 8. By means of graduated withdrawal of the stylet the fluid can be made to ascend the measuring arm of the graduated manometer or allowed to drop slowly from an exit provided. To inject medicated fluids or sera this exit is plugged with a small stylet, the pressure manometer removed and the syringe

or gravity apparatus attached here. The whole apparatus is easily sterilized by boiling. The apparatus of J. M. Wolfsohn 64 is an ingenious contrivance, being practically a Quincke platinum-iridium needle with a three-way stop-cock. A very small amount of fluid, about twelve drops, is needed for the reading of the pressure in the graduated manometer, and one of the arms of the cock can be used for the injection of fluids.

Frazier 65 uses a needle with a three-way stop-cock attached, provided with a stylet. The pressure reading tube, which is small and can be conveniently carried in the pocket, is a mercury manometer and fits into one of the arms of the stop-cock. To those preferring a

These new pages 475-549 are to be inserted in place of the old pages 475-549, Volume I, Tice's Practice of Medicine.

FIG. 6.-LUMBAR PUNCTURE: INTRODUCTION OF THE NEEDLE. Needle having been pushed through the skin is being advanced gently forward into the subarachnoid space. Note position of hands and needle.

mercury manometer this apparatus is recommended. The writer prefers the water manometer, it being simpler and less expensive and just as accurate and reliable.

One of these types of apparatus is necessary if pressure readings are to be taken, although an inexpensive apparatus can be devised by purchasing a heavy manometer tube of 1 mm. bore, calibrating it for the purpose and fitting it on one arm of a three-way stop-cock. In all cases where a tumor in the posterior fossa is suspected, it is advisable to use a manometer and to withdraw a very small amount of fluid, if examination of the fluid is necessary. The stop-cock should accurately fit the hub of the puncture needle. An inexpensive apparatus

for puncture and treatment can also easily be devised. A half-ounce glass catheter-tipped syringe or the barrel of a 20 c.c. Record or Luer syringe, to which twelve inches of rubber tubing is attached, and to the other end of which tubing is placed a small metal adapter to fit the hub of the puncture needle, serves as an injecting funnel (Fig. 4).

Needle in position with both tubes of manometer attached for pressure reading. Stylet of needle completely withdrawn and fluid mounting in calibrated tube.

Site of Puncture.-Ordinarily an imaginary line drawn between the crests of the ileum will intersect the spine at the proper level for puncture, i.e., just below the 4th lumbar spinous process. The needle is introduced in the midline (to avoid the roots of the cauda equina, which are about 2-5 mm. apart) exactly between the spinous processes of the 3d-4th or 4th-5th lumbar vertebræ or in the lumbosacral space. In

These new pages 475-549 are to be inserted in place of the old pages 475-549, Volume I, Tice's Practice of Medicine.

children the lower sites are preferable, for while in the adult the lowest portion of the cord rarely reaches beyond the 2d lumbar vertebra, in infants the conus medullaris may occasionally reach the 3d lumbar vertebra. The terminal nerve roots making up the cauda equina branch off at an angle from the cord along the lumbar region, and the studies.

of Lusk 6 have shown that the only vertebral interspaces through which puncture of the subarachnoid space can be made with practical assurance that nerve structures will not be perforated, are the 4th lumbar or lumbosacral-preferably the former. In individuals with spondylitis of the lumbar vertebræ or marked curvature, allowance must be made for the alteration in the position of the interspinous spaces in selecting the site for puncture and in the direction of the needle toward the canal. If there is a cauda equina lesion or if the subarachnoid space at the

level punctured is obliterated, it may be necessary to puncture at a higher level, going between the 3d or 4th, or 2d and 3d lumbar vertebræ. In one case in which puncture at the 4th lumbar space gave a dry tap, successive punctures in the higher spaces gave xanthochromic fluid, and finally clear fluid, and helped to localize the tumor subsequently removed by operation.

The Puncture.-The needle should be inserted midway between the upper and lower spinous process, perpendicular to the skin and parallel to the surface of the operating table or bed (Fig. 5). The needle is first grasped with the shaft between the thumb and index finger, with the hub resting against the center of the palm of the hand-in the position in which one grasps a shoemaker's awl-and pushed through the skin for about one inch only; then the palmar surface of the last phalanx of the index finger is placed on the hub cap of the needle, while the thumb and other fingers grasp the shaft of the needle near the hub and gently push it forward until the point is felt to pierce the membranes and pass into the subarachnoid space (Fig. 6). There will be a give to the needle as the membranes are pierced, and care should be taken not to use too much force, otherwise the anterior wall of the space will be touched and possibly one of the plexuses of veins ruptured, with consequent bleeding into the cerebrospinal fluid. Depending upon the musculature and obesity of the patient, the needle will have to be inserted from 5-10 cm. before this point is reached.* The stylet is now withdrawn slowly, and if the needle is in the subarachnoid space, fluid will be seen to issue from the needle (Fig. 3). If bony resistance is encountered before fluid is obtained, the needle should be withdrawn until within one inch of the skin and the direction of the needle altered slightly either upward or downward or laterally until the membranes are pierced. The needle must not be bent in an effort to change its direction, for fear of snapping it off. Sometimes the needle is in the canal but the lumen of the needle is obstructed by a bit of membrane or exudate or a nerve strand, so that before withdrawing it entirely the stylet may be inserted again and rapidly withdrawn to create suction to clear the needle, or it may be rotated on its axis slightly or very slowly withdrawn a few millimeters or pushed in a bit until fluid issues. When the stylet is withdrawn free blood may issue from the needle, due to hemorrhage from veins upon the membranes in the epidural space. The needle must then be entirely withdrawn, cleansed free of blood, and the patient punctured again. If the fluid issues blood tinged, the hemorrhage is subdural and the fluid usually becomes clearer as it flows, though it may not become wholly free from blood either macroscopically or microscopically. If it is absolutely essential to obtain a blood-free fluid, the patient should be punctured again in the space higher up. The needle having entered the subarachnoid space, it should be allowed to issue drop by drop into a sterile test tube. One to two c.c. are gathered in each of two or three test tubes and will suffice for all the necessary bacteriological and serological tests. If pressure readings

*The needle traverses the following structures in its excursion: skin, subcutaneous tissue, interspinal ligament, subflavous ligament, epidural fat, vein plexus, dura mater, arachnoid. In this region the dura and arachnoid are in contact while the pia invests the cord and nerve roots. The dural sac is between the arachnoid and the pia mater.