Chapter 117. Lateral Cervical Puncture

The safest procedure to obtain cerebrospinal fluid (CSF) is lumbar puncture. However, there are situations where lumbar puncture is either contraindicated or technically not feasible. This includes infections in the lumbar area, obesity, previous spinal surgery, previous spinal fusion, a history of arachnoiditis, and the previous injection of chemotherapeutics. The usual and safe alternative method is a lateral cervical puncture under such circumstances. Cisternal puncture describes the suboccipital access to cisterna magna, a CSF containing space. It is a less frequently used procedure due to the high incidence of complications. As a result, cisternal puncture should be performed by a Neurosurgeon for patients whose CSF cannot be accessed by lumbar puncture or lateral cervical puncture.1

Dr. Mullan introduced a method for performing a percutaneous cordotomy using a lateral cervical puncture in the early 1960s.2 He introduced a strontium-90 needle through the C1-C2 interspace and into the subarachnoid space under fluoroscopic guidance. He then directed the needle anteriorly toward the anterior dura mater to interrupt the spinal thalamic fibers in an attempt to control intractable pain. The lateral cervical puncture is a direct derivative of this technique.

Lateral cervical puncture involves the placement of a spinal needle into the C1-C2 interspace, posterior and inferior to the vertebral artery. The vertebral artery ascends through the foramina in the transverse processes of the cervical vertebrae beginning at the sixth cervical vertebra. It winds behind the lateral mass of the atlas (C1) to enter the skull through the foramen magnum (Figure 117-1). Inserting the needle 1 cm inferior to the tip of the mastoid process and 1 cm posterior from that point will avoid puncturing the vertebral artery (Figure 117-2).

The spinal canal is formed by sequential vertebral foramina and is triangular in shape. Its lateral width is greater than the anteroposterior width. The spinal canal is more spacious in the upper cervical spine allowing for safe placement of a needle into the C1-C2 interspace. The sagittal diameter of the spinal canal is approximately 23 mm at C1 and 20 mm at C2. The cross-sectional area of the cervical spinal canal is greatest at C2 and progressively decreases. It is smallest at the level of C7. The vertebral canal is narrower in women than in men. The spinal canal at the level of C1-C2 can be divided into three parts. The anterior third is occupied by the odontoid process. The middle third is occupied by the spinal cord itself. The posterior third is occupied by the subarachnoid space. The spinal cord is suspended and cushioned within the subarachnoid space by cerebral spinal fluid. The anterior boundary of the spinal canal is formed by the posterior aspect of the vertebral bodies and the intervertebral disks. The lateral wall of the spinal canal is formed by the pedicles and the intervertebral foramen. The posterior wall of the spinal canal is formed by the lamina, the ligamentum flavum, and the lateral masses or articular processes.

The morphology of the spinal cord demonstrates considerable individual variation in size and shape. The spinal cord changes in morphology throughout the entire spinal canal. It is cylindrical in shape and larger in transverse diameter than anteroposterior diameter. The spinal cord is largest from C3 to C6, obtaining approximately 13 to 14 mm in maximal transverse diameter. The average sagittal diameter of the cervical spinal cord is approximately 11 mm at C1 and 10 mm at C2.

The cervical nerve roots usually occupy the inferior one-third of the neural foramen. The first cervical spinal nerve root exits between the occiput and C1. The C2 through C7 spinal nerves exit above their corresponding numbered vertebra. Each nerve root innervates a specific dermatome and myotome, with considerable anatomical variation and overlap. The C1-C2 interspace is guarded laterally by the ligamentum flavum. The ligamentum flavum is composed of a yellow elastic tissue, the fibers of which are almost perpendicular in direction. It is attached to the lower part of the anterior surface of the lamina above and the posterior surface of the upper margin of the lamina below.

The lateral cervical puncture is an alternative method for obtaining CSF when lumbar puncture is not feasible or successful. Conditions that make lumbar puncture difficult are considered contraindications such as lumbar arachnoiditis, marked obesity, infections in the lumbar area, prior lumbar spine surgery, prior administration of lumbar intrathecal chemotherapeutics, and known congenital anomalies of the lumbar area (e.g., meningocele and myelomeningocele). The lateral cervical puncture is performed, like the lumbar puncture, in order to obtain CSF for analysis. CSF analysis is indicated in patients suspected of having a central nervous system infection or a subarachnoid hemorrhage. Other indications for lateral cervical puncture include the installation of antineoplastic or antimicrobial agents. Lateral cervical puncture may also be necessary for the introduction of dye for radiographic studies.

Contraindications for a lateral cervical puncture include brain abscesses, brain tumors, cervical spine anomalies and deformities, coagulopathy, increased intracranial pressure, inflammatory adhesions, local infections, posterior fossa abscesses, posterior fossa tumors, thrombocytopenia, and vertebral artery anomalies (course or location). Arnold-Chiari malformations and other congenital abnormalities in the region of the foramen magnum are also a relative contraindication. These include achondroplasia, basilar impression, Dandy-Walker malformation, Klippel–Feil syndrome, and syringomyelia.

• Sterile gloves and gown
• Face mask with an eye shield or goggles
• Cap
• 20 gauge spinal needle with a stylet
• 23 gauge spinal needle with a stylet
• 3 mL syringe
• 20 gauge needles
• 22 gauge needles
• Three-way stopcock
• Manometer
• Extension tubing, optional
• Four specimen vials with caps
• Gauze pads
• Sterile towels
• Fenestrated sterile drape
• Lidocaine hydrochloride, 1%
• Sterile gloves
• Povidone iodine or chlorhexidine solution
• Fluoroscopy unit, optional

All of the basic equipment can be found in commercially available lumbar puncture kits. The kit needs to be supplemented with personal protective equipment and skin antiseptic.

The patient should be fully monitored with a noninvasive blood pressure cuff, pulse oximetry, cardiac monitor, and end-tidal carbon dioxide monitor (if available). Obtain a CT scan of the head if a complete neurological examination cannot be performed or if it is abnormal in any way, the patient has a history of malignancy, of the patient may have a potential mass occupying lesion (e.g., the HIV patient). Obtain a complete blood count (hemoglobin, hematocrit, and platelet count) and a coagulation profile (PT, PTT, and INR) to ensure that the patient is not thrombocytopenic or coagulopathic. Do not delay the administration of intravenous antibiotics pending these studies if meningitis is in the differential diagnosis and the reason for the lateral cervical puncture.

Explain the procedure, its risks, and benefits to the patient and/or their representative. Explain the postprocedural care. Obtain an informed consent for the procedure. Place the patient supine on the gurney, without a pillow, and the neck as straight as possible. Limit any head rotation from the true supine position. The landmark for needle insertion is 1 cm caudal and 1 cm posterior to the tip of the mastoid process (Figure 117-2).

This procedure requires strict aseptic technique. Clean the skin of any dirt and debris. Swab the area with alcohol pads. Shave the area so that the mastoid tip is contained within the sterile field. The Emergency Physician should don full sterile and personal protective equipment at this point. This should include sterile gloves, a sterile gown, a face mask with an eye shield or goggles, and a cap. Apply povidone iodine or chlorhexidine solution to the skin and allow it to dry. Apply sterile towels and drapes to delineate a sterile field. Inject local anesthetic solution subcutaneously at the above identified landmark. Consider the administration of intravenous diazepam or midazolam, if not contraindicated, to relax the patient. Some patients may require the administration of procedural sedation. The aid of an assistant to hold the patient's head straight and upright is recommended.

Maintain the patient in the supine position with absolutely no head movement. An assistant should stabilize the patient's head. Introduce a 21 or 22 gauge spinal needle perfectly horizontal, parallel to the plane of the bed, and perpendicular to the neck (Figure 117-3). The needle will cross a number of tissue planes including the skin, subcutaneous tissue, trapezius muscle, suboccipital muscles, and the meninges. Advance the needle slowly and in 2 to 3 mm increments. Remove the stylette frequently to check for CSF. The subarachnoid space is approximately 6 cm from the skin surface in most adults. Puncture of the dura is often felt as a “pop” or loss of resistance. Frequent checks for CSF prevent excessive penetration of the needle through subarachnoid space, overshooting the spinal canal, or inadvertent puncture of the spinal cord or vertebral artery. Immediately remove the spinal needle if the patient develops any neurological symptoms.

CSF flow through the needle signifies that the tip is within the subarachnoid space. If CSF is not draining after puncture of the dura and removal of the stylet, rotate the needle 30°. The use of a portable fluoroscopic unit can confirm the needle's trajectory and exact position. Carefully apply the three-way stopcock and manometer to the spinal needle to measure the pressure of the CSF. Carefully remove the stopcock and the manometer from the spinal needle. Do not allow the spinal needle to move while applying and removing the stopcock and manometer. Keep in mind that the needle is not very well supported by the soft tissue as in the lumbar puncture. Hence, the needle must be supported more carefully. Collect 1 to 2 mL of CSF in each specimen tube. Insert the stylet into the spinal needle. Remove the spinal needle and stylet as a unit. Apply a bandage to the skin puncture site.

Encountering arterial blood from the spinal needle usually indicates that it was pointing too far anteriorly and that the vertebral artery was penetrated. The venous plexus surrounding the vertebral artery may also be penetrated. Remove the spinal needle and apply manual pressure if the vertebral artery is inadvertently entered. Reattempt the procedure with the tip of the spinal needle directed slightly more posteriorly. Directing the spinal needle too far posteriorly causes it to enter the spinal musculature and miss the spinal canal. In the event that bone is encountered, meaning that either the lateral arch of C1 or C2 is encountered, redirect the spinal needle slightly rostrally or caudally and advance it into the subarachnoid space.

Maintain the patient in a supine position after the procedure. A small bandage is usually sufficient to control any soft tissue bleeding or continued CSF leakage. Postdural puncture headaches can be minimized by utilizing a small-gauged spinal needle inserted with the bevel parallel to the fibers of the dura. Resting in the supine position for 24 hours also reduces the incidence of postdural puncture headaches. Monitor the patient's neurological status. Any change in patient's baseline neurological examination requires a CT scan of the brain, posterior fossa, and occipital-cervical junction in order to rule out a herniation, epidural hematoma, or intradural hemorrhage.

Send the aspirated fluid for the appropriate laboratory analysis if an etiology other than an acute traumatic hemorrhage is suspected.3 This can include a biochemistry analysis (glucose and protein level), cell count and differential, culture (bacterial, fungal, viral, etc.), cytology, and gram stain.

The complications associated with lumbar puncture are also possible during the lateral cervical puncture. Specific complications from lateral cervical puncture include penetration of the vertebral artery with subsequent hematoma formation and puncture of the spinal cord with resultant neurological deficits.3–8 Minimize complications by utilizing a small gauge spinal needle. These complications should result in no serious consequences if unilateral and recognized.3 Approximately 0.4% of the population has an anomalously positioned vertebral artery. There has been a single case report of a death from a subdural hematoma due to puncture of this vessel.4 A nerve root may be irritated with passage of the needle resulting in local pain or possibly a headache. Other complications include infection, herniation syndromes, neck pain, and headache. The incidence of postdural puncture headache is less with the lateral cervical puncture than with a lumbar puncture. Refer to Chapter 115 for the complete details regarding the complications associated with a lumbar puncture.

A lumbar puncture is still the preferred technique to obtain cerebrospinal fluid for analysis as well as for injection of contrast material. The lateral cervical puncture is a safe alternative method. One can avoid the complications of puncturing the vertebral artery or the spinal cord by observing maximum attention to detail. The lateral cervical puncture can be performed at the bedside. However, the availability of a portable fluoroscopy unit can facilitate the procedure.