Trigger point injections are generally considered to be fairly straightforward; however, some catastrophic complications have been described in cases without fluoroscopy. In a closed claims study, the second most common cause of pneumothorax behind intercostal nerve block was trigger point injection, being responsible for 21 % of cases [5].

Other documented complications include local infection, cellulitis, hematoma, epidural abscess, pneumothorax, spinal anesthesia, spinal cord injury, anaphylaxis, and death.

Use of fluoroscopy for trigger point injections in the cervical or thoracic area will help reduce needle misplacement, either into the epidural, subdural, subarachnoid space, or into the spinal cord, which has occurred with trigger point injections of paraspinal muscles. The use of lateral fluoroscopic guidance for trigger point injections of any posterior thoracic wall musculature will document needle depth and prevent pneumothorax by remaining superficial to the ribs [50–52].

In general, lumbar zygapophysial (facet) joint injection is a safe procedure, although complications similar to epidural steroid injections have been described. These include infection with resulting cellulitis or epidural abscess, epidural hematoma, intravascular injection, dural puncture, spinal anesthesia, spinal cord trauma, neural trauma, chemical meningitis, and pneumothorax. Vertebral artery damage or injection is a potential risk with cervical facet joint injections [53–59]. With the use of fluoroscopy and contrast injection in experienced hands, serious complications should not occur. In the cervical spine, a posterior parasagittal approach to the medial branch nerves or posterior approach to the interarticular z-joint injection is safer than a lateral approach (Fig. 50.5). A lateral approach brings the contents of the spinal canal potentially into the path of the needle, especially if the clinician is unable to eliminate parallax and get a true lateral fluoroscopic image. Potential for going through and through a facet joint is real if needle depth is not checked frequently as the needle is advanced. Ideally, under tunnel vision, the periosteum of the adjacent articular process should be intentionally contacted prior to entering the joint to confirm depth and then the needle rotated into the joint. This will help prevent the needle going through the joint to the adjacent tissue [60].

Many techniques have been described for stellate ganglion block, some of which are without fluoroscopic guidance [61–63]. Multiple complications have been described, most of which have occurred from nonfluoroscopically guided injections that have resulted in inadvertent needle placement into the vertebral artery, adjacent disc, neurotissue, esophagus, intrathecal space, or pleura. These complications have included seizures from intravascular injection, spinal anesthesia, cervical epidural abscess, brachial plexus block, intercostal neuralgia, locked-in syndrome, pneumochylothorax, pneumothorax, reversible blindness, hoarseness, dysphagia, and death [64–74]. These complications can be reduced or hopefully eliminated with a technique described by Abdi et al. [75].

Under ipsilateral oblique fluoroscopic guidance, the respective endplates are squared off, and the C-arm is obliqued until a crisp C7 uncinate process is visualized. Then a 25-gauge spinal needle is advanced down, under tunnel vision, to the base of the uncinate process at the junction of the vertebral body. Under live fluoroscopic guidance with extension tubing, injection of contrast is performed to confirm appropriate nonvascular contrast flow. The needle will lie anterior to the vertebral artery, posterior to the common carotid artery, and lateral to the esophagus. A total of 5 cc should be adequate to obtain stellate ganglion blockade.

In experienced hands, discography is safe, whether that be in the cervical, lumbar, or thoracic spine. Understanding indications and contraindications to discography is important. Coagulopathy and active infection are general contraindications, but central spinal stenosis, myelopathy, and large disc protrusion are contraindications to cervical or thoracic discography [76].

Potential and described complications pertinent to all three areas include superficial infection, epidural abscess, discitis, or nerve root injury. In the cervical or thoracic spine, the potential for spinal cord injury exists. Quadriplegia has been described following epidural hematoma, epidural abscess, and from subdural empyema [77–84]. It has also occurred secondary to cervical disc herniation from disc pressurization at discography. Keeping the contrast volume in cervical or thoracic discography to a minimum is also important, with less than 0.5 cc/disc usually sufficient for cervical discography.

While infection is a real concern, the administration of preoperative intravenous antibiotics, intradiscal antibiotics, and/or a coaxial needle technique has been described in the literature to be able to reduce the incidence of infection (Fig. 50.6).

A coaxial needle technique has been shown to reduce the chance of discitis from 2.7 to 0.7 % in 220 patients [85]. Preoperative intravenous cefazolin has been shown to reduce the chance of disc infection from 1 to 4 % down to 0 %. Utilizing cefazolin in a concentration of 1 mg/cc intradiscally resulted in no intradiscal infections of 127 patients [86, 87].

The prophylactic antibiotics commonly utilized do not prevent anaerobic discitis, which may occur with the anterior approach to cervical discography, where esophageal penetration is possible. Utilizing a right anterolateral (oblique) approach reduces the chance for esophageal perforation and consequent potential anaerobic discitis. Auscultation of the carotid artery should be performed and ultrasound ordered if carotid bruits are heard prior to discography if an oblique approach is utilized, because of the potential of the needle traversing the carotid and dislodging an unstable plaque.

Patients with discitis usually present with pain and fever, 3 days to 2 weeks post-discography. Erythrocyte sedimentation rate, white cell count, and C-reactive protein are usually positive within the first week. It may take anywhere from 2 to 5 weeks for a bone scan to become positive. MRI with or without gadolinium is now considered the gold standard imaging study. If discitis is suspected, infectious disease consultation, disc biopsy, and culture should be taken. IV antibiotics should be started, and consideration should be given for surgical exploration and/or bracing.

Many of the complications reported with lumbar discography were reported prior to 1970, with many of them in the 1950s. Today with preoperative intravenous antibiotics, intradiscal antibiotics, and a coaxial needle technique, with extrapedicular, extradural fluoroscopically guided approach, these complications should be minimal [88, 89].

If a posterior transdural approach to a disc is planned, then it is important not to utilize intradiscal cefazolin because of the potential for intractable seizures with inadvertent intrathecal cefazolin injection. Therefore, in a patient with previous posterolateral intratransverse bony fusion mass, when posterior transdural approach is considered, or if inadvertent dural puncture occurs with extrapedicular, extradural approach to the disc, then contrast should be mixed with another antibiotic besides cefazolin, such as ceftriaxone, gentamicin, or clindamycin [90].

Pneumothorax has been described as a complication of thoracic discography but could also occur with cervical discography at the C7/T1 level.

In general, cervical or thoracic discography, because of the more challenging technical aspects, and potential for more catastrophic complications, should only be performed by highly skilled and experienced interventionalists.

It is important to know the literature on current technical standards, modify practice accordingly, and understand that many complications are never published. History and physical examination should be performed on all patients prior to spinal injections. Physicians should review pertinent imaging studies, understand indications and contraindications of procedures, and obtain informed consent. Knowledge of regional and fluoroscopic anatomy is important before attaining technical expertise in a supervised training environment. Familiarization with all contrast flow patterns under live fluoroscopy is imperative. Above all, understand that complications are inevitable, and it is imperative to identify and treat these problems promptly to minimize their impact when they occur and communicate these issues with the patient.

This should include any bleeding diathesis, any immune suppressive disorder, history of allergy, anaphylaxis or asthma, and whether they have valvular heart disease.

It is important to note whether the patient is taking any oral steroid, antibiotics, anticoagulants, or Glucophage, as these will impact patient outcome. Glucophage is generally considered safe in patients with normal renal function when a small amount of nonionic contrast is utilized. It should be temporarily discontinued in patients with impaired renal function undergoing procedures requiring larger amounts of contrast, as it may result in the patient developing lactic acidosis.

Patients taking oral steroids will not only be immunosuppressed but also at increased risk of potential side effects from steroids [91].

Anticoagulants will clearly put patients at risk for hemorrhagic complications. Knowledge of prescription and over-the-counter medications and herbal remedies is important in risk-stratifying patients.

Neuraxial blocks on patients with an active infection requiring antibiotics should be postponed because of the potential for bacteremia and introduction of bacteria to the epidural space.

Knowledge of patient allergic to medications that may be utilized in a procedure such as steroid, local anesthetic, or antibiotics is important in reducing the chance of anaphylactic reaction. It is also important to document any known allergy to shellfish or iodine if contrast is to be utilized and any latex allergy, as these procedures need to be done, first case of the day, in a latex-free environment. (Gadolinium may be used in iodine-allergic patients, although there is a documented cross allergy to gadolinium.)

Thorough review of systems should help rule out any occult coagulopathy, infection, cord compression, malignancy, or pregnant state.

This should include any prior litigation as even more thorough documentation and informed consent may be required.

A general but also procedure-specific physical examination should be performed. Attention should be paid to whether the patient is hemodynamically unstable or febrile, as elective procedures should be rescheduled in that event.

A thorough neurological examination is important to establish as a baseline, especially in the event of an adverse neurological outcome. Knowledge of a carotid bruit and subsequent Doppler study result is vital in patients undergoing procedures, in which the carotid artery may be penetrated, such as cervical discography, as the potential for dislodging a mobile thrombus is real. A thorough cardiopulmonary assessment is important in patients undergoing conscious sedation.

Interventional pain physicians should be to the spine, what the cardiologist is to the heart. They should be comfortable with not only the medical and interventional management of these patients but as good, if not better, than the radiologist in interpreting pertinent spinal imaging studies. Reviewing the imaging prior to procedure in all patients is important [30, 76].

If the physician is not drawing up the medications for injection, then appropriate education and training of the surgical staff is vital in reducing medication errors. Medication should be drawn up by a surgical technician with nursing supervision. All syringes should be labeled, and clearly, sterile precautions must be followed.

If you practice in a setting that is used by different specialists, such as a radiology suite at a hospital, it is important that the physician reviews all the medications prior to each procedure, to ensure no medication error. Specifically, that preservative-free local anesthetics are utilized (for epidural injections), and nonionic contrast that is safe for intrathecal use, such as Omnipaque or Isovue, and not an ionic contrast medium that may be used for urologic or gastrointestinal imaging.

Appropriate sterile preparation is mandatory and should include povidone-iodine preparation, allowing it to dry. In patients with iodine allergy, chlorhexidine gluconate and/or isopropyl alcohol may be used. For more invasive procedures such as implant or discography, some practices utilize a triple scrub, including isopropyl alcohol, chlorhexidine gluconate, and povidone-iodine. While sterile towels are adequate for draping an area for most procedures, in the case of more invasive spinal procedures, full-body draping with iodine-impregnated fenestrated adhesive biodrapes, sterile towels, and half sheets should be used [92, 93].