Complications Associated with Head and Neck Blocks, Upper Extremity Blocks, Lower Extremity Blocks, and Differential Diagnostic Blocks

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Chapter 12 Complications Associated with Head and Neck Blocks, Upper Extremity Blocks, Lower Extremity Blocks, and Differential Diagnostic Blocks

Collin F.M. Clarke, Pari Azari, Chang Po Kuo, Billy K. Huh

Chapter Overview

Chapter Synopsis: A diverse group of interventional techniques for chronic pain includes head and neck blocks, upper and lower extremity blocks, and differential diagnostic blocks. Although these minimally invasive procedures carry a very low risk, there are rarely catastrophic complications. The consequences vary considerably depending on the site of injection. Sites such as the trigeminal ganglion, buried inside the brain and surrounded by vasculature, pose particular anatomic challenges. Other procedures focus on sites in close anatomic proximity to structures, including nerves, brain, blood vessels, and lungs, and carry risks of particular complications depending on the affected structure.

Important Points:

Appropriate patient selection with definitive endpoints of treatment is paramount.

Procedures should only be performed by or under the direct supervision of those who have subspecialty training in interventional pain management.

Development of standardized procedural approaches, including preprocedure timeouts and sterile techniques, may decrease the likelihood of adverse events.

Thorough understanding of relevant anatomy and the ability to use imaging, whether fluoroscopy or ultrasonography, are vital to procedural success.

Although uncommon, catastrophic complications have been reported.

Complications related to the spine, major vessels, and airway may require emergent surgical intervention. Early recognition is imperative.

Introduction

As with any medical procedure, the physician performing the procedure should weigh the benefits versus the risks. Interventional procedures have significant potential benefit for those suffering from chronic pain. Although uncommon, complications may result in catastrophic outcomes. This chapter reviews the complications associated with a diverse group of procedures, including head and neck blocks, upper extremity blocks, lower extremity blocks, and differential diagnostic blocks. The complications associated with these can generally be divided into vascular, infectious, neural, pharmacologic, and anatomically related to the specific sight of injection (Table 12-1).

Table 12-1 Overview of Complications Associated with Head and Neck Block, Upper Extremity Block, Lower Extremity Block, and Differential Diagnostic Block Procedures

Vascular¹^–⁶

• Hematoma

• Airway compression

• Neural compression

• Microvascular compression

• Vascular insufficiency secondary to vasospasm

Infectious

Pharmacologic

• Cardiovascular toxicity

• High or total spinal

• Steroid

• Pituitary adrenal axis suppression

• Particulate steroid-induced vascular occlusion

Neural^2,¹⁴^–¹⁶

• Direct needle trauma

• Barotrauma from high-pressure injection

• Compression from hematoma

• Local anesthetic neural toxicity

CNS, central nervous system.

Vascular

Many neural structures are intimately connected with vasculature. Overall, the likelihood of a vascular complication is rare but potentially devastating. Reported vascular complications include airway, neural, and microvascular compression related to hematoma formation.¹^–³ Additionally, arterial dissection, pseudoaneurysm, and vascular insufficiency secondary to vasospasm have all been cited in the literature.⁴^–⁶

Infection

The likelihood of infection from any single injection is extremely rare. Infection requiring intervention after an indwelling catheter has been reported as high as 0.8%.⁷ With interventional procedures involving the neuraxis, terrible sequelae, including epidural abscess or meningitis, may occur. Evidence demonstrates that catheter insertion (particularly >48 hours), intensive care unit admission, male sex, lack of prophylactic antibiotics, and lack of provider experience increase the likelihood of infection.⁸

Local Anesthetic Toxicity

The proximity of many neural structures to major vessels predisposes itself to the potential for local anesthetic toxicity. Inadvertent vascular puncture is the most likely cause of toxicity, but it has been suggested that with no identifiable puncture, clinical doses may cause toxicity.⁹ It appears that clinically significant local anesthetic toxicity occurs between 7.5 and 20 times per 10000 regional anesthetics.¹⁰ Local anesthetic toxicity can be categorized by symptoms involving the central nervous system (CNS) and those related to cardiovascular toxicity (Table 12-2).

Table 12-2 Signs and Symptoms Associated with Local Anesthetic Toxicity

Central nervous system¹¹

• Tonic-clonic seizure

Cardiovascular¹²

• Initially hypertension and tachycardia caused by CNS excitation

• Myocardial depression

• Ventricular arrhythmias

• Conduction delays

• Profound contractile dysfunction

• Eventual cardiovascular collapse

CNS, central nervous system.

Neurologic

The likelihood of long-term neurologic injury is low, reported below 0.02%.¹³ When these injuries do occur, the outcome is often devastating to the clinician and patient alike. Nerve injury may present in a spectrum from paresthesias to paralysis, with neuropathic pain being a dreaded outcome.

Etiologies attributed to nerve injury include direct needle trauma, barotrauma from high-pressure injection, compression from hematoma, and local anesthetic neural toxicity.^2,¹⁴^–¹⁶

Complications of Head and Neck Blocks

Head and neck blocks are indispensable in management of various orofacial pain and headache syndromes. However, because of the limited space and close proximity to important structures such as arteries, nerves, brain, and lungs, there is potential for significant complications. The most common complications of head and neck procedures are related to injury to blood vessels leading to bleeding and systemic toxicity from vascular or subdural injection of local anesthetics, which can cause seizure, hemodynamic instability, or even cardiac arrest. Therefore, image-guided (fluoroscopy or ultrasonography) needle placement is highly recommended when performing procedures in the head and neck area. The collateral damage to surrounding structures from needle, radiofrequency ablation (RFA), chemical ablation, or balloon compression can vary depending on the specific anatomic location of the targets.

A variety of percutaneous techniques are available for targets at head and neck, including sphenopalatine ganglion (SPG), Gasserian ganglion, atlantoaxial joint (AAJ) and atlantooccipital joint (AOJ), stellate ganglion, and C2 dorsal root ganglion. See Table 12-3 for a description of complications associated with head and neck injections.

Table 12-3 Common Head and Neck Blocks with Associated Complications

Gasserian ganglion block and neurolysis^17,³²

• Brainstem anesthesia

• Significant bleed

• CSF leak

• Permanent trigeminal sensory loss

SPG block²⁰^–²⁴

• Cheek hematoma (most common complication)

• Epistaxis (more frequent with intranasal approach)

• Intravascular injection

• Hematoma formation within the PPF

• Reflex bradycardia is likely with RFA because of the rich parasympathetic connections to the SPG

• Permanent or temporary hyperesthesia or dysesthesia in the palate, maxilla, or posterior pharynx

• Temporary diplopia

AAJ and AOJ injections¹⁹

• Seizure secondary to vertebral artery injection

Stellate ganglion block^1,^33,³⁴

• Horner syndrome

• Recurrent laryngeal nerve block

• Vagus nerve block

• Phrenic nerve block

• Hematoma

• Airway compromise

• Disc perforation

• Esophageal perforation

• High spinal block

C2 dorsal root ganglion injection

• Total spinal block leading to a rapid decrease in blood pressure and difficulty breathing

• Nerve damage, paralysis, stroke, and even death

AAJ, atlantoaxial joint; AOJ, atlantooccipital joint; CSF, cerebrospinal fluid; PPF, pterygopalatine fossa; RFA, radiofrequency ablation; SPG, sphenopalatine ganglion.

Gasserian Ganglion Block and Neurolysis

The Gasserian (trigeminal) ganglion lies within the Meckel cave, which contains cerebrospinal fluid (CSF), and local anesthetic deposited in this area may spread to other cranial nerves and can potentially cause brainstem anesthesia.¹⁷ Infection, CSF leak, bleeding, and nerve damage are also likely with Gasserian ganglion block or ablation because it is located in the middle of the brain surrounded by blood vessels. Literature studies show that RFA of the Gasserian ganglion is associated with the highest incidence of complications, with nearly one-third of patients developing some form of complications.¹⁸ Postoperative trigeminal sensory loss affects virtually all patients treated with RFA, and it is considered a side effect rather than a complication.

Sphenopalatine Ganglion Block

Epistaxis is more frequent with an intranasal approach to SPG block; intravascular injection or hematoma formation can occur after maxillary artery injury, which lies within the pterygopalatine fossa (PPF). Cheek hematoma is the most common complication. Infection is always possible especially with inadvertent needle entry into the nasal or oral cavity.¹⁹ Reflex bradycardia is likely with RFA because of the rich parasympathetic connections to the SPG.²⁰ RFA of the SPG can result in permanent or temporary hyperesthesia or dysesthesia in the palate, maxilla, or posterior pharynx.²¹^–²³ Temporary diplopia, which is more common after local anesthetic injections rather than RFA, is caused by the spread of the injectate from the PPF to the inferior orbital fissure containing the abducent nerve.²⁴ Temporary diplopia is likely if the needle tip is deep inside the PPF and the volume of injectate is greater than 1 to 2 mL.

Atlantoaxial Joint and Atlantooccipital Joint Injections

The AAJ and AOJ are in very close proximity to the vertebral artery (Fig. 12-1). Consequently, particular attention should be paid to avoid intravascular injection because vertebral artery anatomy can be unpredictable. Intraarterial injection may cause seizure or posterior circulation stroke.²⁵ Inadvertent puncture of the C2 dural sleeve with CSF leak or high spinal spread of the local anesthetic may occur with AAJ injection if the needle is directed too medially. This can result in a rapid and profound decrease in blood pressure followed by apnea and death. Therefore, intravenous access should be established before the procedure. Spinal cord injury and syringomyelia are potential serious complications if the needle is directed even further medially.¹⁹

Fig. 12-1 The close proximity of the vertebral artery to the atlantooccipital joint (AOJ) and atlantoaxial joint (AAJ) to the vertebral artery results in a significant risk of intraarterial injection.

(Modified from Edlow BL, Wainger BJ, Frosch MP, et al: Posterior circulation stroke after C1-C2 intraarticular facet steroid injection: evidence for diffuse microvascular injury, Anesthesiology 112:1532-1535, 2010.)

Stellate Ganglion Block

Many important structures lie close to the stellate ganglion. Hence, technical complications from injury to the nerves and viscera are possible during insertion of the needle.^17,^26,²⁷ This includes injury to the brachial plexus; trauma to the trachea and esophagus; injury to the pleura and lung (pneumothorax, hemothorax, which may require chest tube insertion); and bleeding and local hematoma, especially if the patient was taking anticoagulants. This can lead to airway compression (Fig. 12-2).^28,²⁹ Vasovagal attacks can also occur, especially with inadvertent manipulation of carotid sinus during the block. Infectious complications are possible if there was a breach in the aseptic barrier. These can include local abscess, cellulitis, and osteitis of the vertebral body and transverse process.³⁰

Fig. 12-2 Large retropharyngeal hematoma resulting in airway obstruction extending into the mediastinum after stellate ganglion block. Demonstrated on T2-weighted magnetic resonance image.

(From Mishio M, Matsumoto T, Okuda Y, Kitajima T: Delayed severe airway obstruction due to hematoma following stellate ganglion block, Reg Anesth Pain Med 23:516-519, 1998.)

Complications related to the injectates include dose, volume, type of local anesthetic and site of deposition of the solution. Accidental block of the recurrent laryngeal nerve can cause hoarseness of voice while phrenic nerve paralysis can lead to respiratory depression especially if there is contralateral dysfunction of the phrenic nerve, or in patients with a preexisting respiratory problem. Therefore, bilateral stellate ganglia block is generally not recommended.^17,²⁶ Intraarterial injection into the vertebral artery or the carotid artery can produce a high concentration of local anesthetic agent in the CNS, leading to seizures. Intravenous injection can also lead to seizure, if a high volume of local anesthetic is used.¹⁷ Medial epidural spread and intrathecal injection of local anesthetic, producing high spinal blockade, has also been documented. Horner syndrome is often the final consequence of sympathetic blockade; although not a complication, it can be unpleasant. Air embolism has also been reported. Loss of cardioaccelerator activity may lead to various bradyarrhythmias and hypotension.¹⁷

Complications from RFA are similar to the complications produced by local anesthetic sympathetic ganglia block, with the exception of a longer lasting block and potential neuritis. Because of an increased chance of injury to the surrounding structures, phenol or alcohol neurolysis is not recommended.³¹

C2 Dorsal Root Ganglion Injection

The C2 dorsal root ganglion block is an injection performed on the cervical spine to relieve headaches that originate from the C2 level. A needle is placed near the second cervical vertebral foramen at the location of the exiting C2 nerve root where the ganglion exists. Correct location of the needle tip should be always confirmed with the assistance of fluoroscopy before local anesthetic is injected or the ablation procedure is performed.

Complications of Upper Extremity Blocks

Upper extremity blockade is most commonly performed in the perioperative environment for intraoperative and postoperative analgesia. Physicians performing these procedures should consider the use of ultrasound to minimize the risks associated with peripheral nerve blocks. The majority of literature regarding this blockade comes from practitioners of regional anesthesia. However, upper extremity blockade may be a useful tool to the pain clinician for treatment and diagnosis. In the case of upper extremity neural blockade, complications can generally be divided into vascular, infectious, neural, local anesthetic toxicity, and anatomically related to the specific site of injection (Table 12-4). A large French study has reported that the overall incidence of serious complication from peripheral nerve block is 0.04%.¹³

Table 12-4 Upper Extremity Blocks and Their Site-Specific Advantages and Complications

Interscalene block⁴⁴^–⁴⁹

• Pneumothoraces

• Prolonged phrenic nerve palsy

• Recurrent laryngeal nerve palsy

• Prolonged Horner syndrome

• Intrathecal block

• Epidural block

Supraclavicular block³⁷^–⁴⁰

• Transient phrenic nerve paresis (≈50% of patients)

• Transient Horner syndrome

• Recurrent laryngeal involvement

• Pneumothorax

Infraclavicular block^38,³⁹

• Distanced from central and neuraxial structures

• Pneumothoraces have been reported ^42,⁴³

Axillary block³⁷

• Distanced from the centroneuraxis structures

• Increased potential for vascular uptake secondary to technique for injection

The brachial plexus is intimately connected with a variety of vascular structures. Overall, the likelihood of a vascular complication is rare but potentially devastating. Reported vascular complications include hematoma, resulting in airway, neural, and microvascular compression.¹^–³ Arterial dissection, pseudoaneurysm, and vascular insufficiency secondary to vasospasm have also been reported.⁴^–⁶

The likelihood of long-term neural injury is low, reported below 0.02%.¹³ When these injuries do occur, the outcome is often devastating to the clinician and patient alike. Nerve injury may present in a spectrum of paresthesias, paralysis, and neuropathic pain.

The proximity of the brachial plexus to major vascular structures predisposes itself to the potential for local anesthetic toxicity. Inadvertent vascular puncture is the most likely cause of toxicity, but it has been suggested that even with no identifiable puncture clinical doses may cause toxicity.⁹ Clinically significant local anesthetic toxicity occurs between 7.5 and 20 times per 10,000 regional anesthetics.¹⁰

Interscalene Block

The approach at the interscalene level carries the greatest anatomic risk because it is adjacent to many central structures. Some reports state a complication rate as high as 1.1%³⁵ This approach yields an almost 100% incidence of unilateral phrenic nerve palsy (Fig. 12-3) and should be used with caution in those with respiratory insufficiency.³⁶

Fig. 12-3 Chest radiograph typical of a right phrenic nerve palsy after interscalene block.

(From Cangiani L, Rezende L, Neto A: Phrenic nerve block after interscalene brachial plexus block. Case report, Rev Bras Anestesiol 58:7, 2008.)

Supraclavicular Block

The supraclavicular nerve block has the advantage of being slightly farther away from the central and neuraxial structures but does consistently miss the long thoracic and dorsal scapular nerves and may miss the subclavius and suprascapular nerves, all of which may be important to complete shoulder blockade.³ It does, however, remain close enough that local anesthesia spread involves the phrenic nerve in about 50% of patients.³⁷ Additionally, reports have shown transient Horner syndrome and recurrent laryngeal involvement with this approach.^38,³⁹ It has been suggested that there is an increased likelihood of pneumothorax with this approach compared with the infraclavicular approach (Fig. 12-4).^40,⁴¹

Fig. 12-4 Right pneumothorax (arrows) after a right supraclavicular block.

(From Bhatia A, Lai J, Chan VW, Brull R: Case report: pneumothorax as a complication of the ultrasound-guided supraclavicular approach for brachial plexus block, Anesth Analg 111:817-819, 2010.)

Infraclavicular Block

Axillary Block

The axillary injection site for brachial plexus blockade carries the least risk for structural injury and complication because of its distance from centroneuraxis structures. The one potential complication that some authors suggest is an increased potential for vascular uptake of the medication because of an increase in distance between intended neural structures, with most providers using a “fanlike” needle technique for injection.³⁷

Complications of Lower Extremity Blocks

The incidence of nerve injury after neural block is very low.⁵⁰ An observational study demonstrated a 1.7% incidence of post-operative neurologic dysfunction after 3996 nerve blocks performed with multiple injection techniques.⁵¹ Complications of lower extremity blocks share many characteristics that are similar from one to another (Table 12-5). The complications could be simply separated as local complications and systemic complications.

Table 12-5 Specific Complications Following Lower Limb Nerve Block

Psoas compartment block⁵⁷^–⁶⁰

• Intrathecal (total spinal anesthesia)

• Epidural spread

• Intravascular injection

• Peripheral nerve damage

• Sympathetic block

Lumbar sympathetic block⁶²^–⁶⁵

• Nerve damage

• Lumbar nerve root injury

• Genitofemoral neuralgia

• Puncture of major vessel

• Renal trauma

• Ureteral trauma

• Local anesthesia toxicity

Three-in-one (femoral) nerve block

• Intravascular injection

• Hematoma

• Nerve damage

Lateral femoral cutaneous nerve block

• Neuritis by needle trauma (unlikely)

• Drug toxicity (unlikely)

• Intravascular injection (rare)

Sciatic nerve block^51,⁶⁸

• Muscle trauma

• Vascular puncture

• Low risk of significant hypotension

• Neuropathy or nerve damage

Nerve blocks at the ankle

• Multiple injections result in discomfort for the patient

• Persisting paresthesias may occur but are usually self-limited

• Intravascular injection is possible but unlikely

• Low incidence of local anesthetic toxicity

Local complications include nerve damage and injury to surrounding anatomic structures. Nerve puncture by the block needle and intraneural injection of local anesthetic is a feared complication and is thought to be a major contributor to neurologic injury after peripheral nerve blocks.⁵² High injection pressure has also been postulated as a cause of neural injury.¹⁵ Fortunately, it has been shown that injection of local anesthetics beyond the epineurium does not result in nerve damage.^52,⁵³ Paresthesia or dysesthesia without motor deficit may be attributable to injury of the nervi nervorum, which innervate the epineurium and mesoneurium.⁵² Leakage around the puncture site, especially when a catheter has been introduced, may favor bacterial contamination. Furthermore, infection may be a result of inadequate sterilization and might result in sepsis or CNS infection. The local complications are avoidable with adequate imaging modalities and applying standard operating procedures. Leakage around the catheter can be reduced by tunneling the catheter and applying a slightly compressive dressing.

Systemic complications usually result from accidental intravascular injection of local anesthetics; less frequently, overzealous administration has been implicated.^54,⁵⁵ These complications can be life threatening, and both adults and children should be managed in the same way. The major difference between adults and children is that cardiovascular complications are often not preceded by neurologic signs but are concomitant with cerebral toxicity.⁵⁶ The incidence of systemic reactions to local anesthetics ranges between 3.9 and 11 in 10,000.⁵⁰

As with upper extremity blockade, the vast majority of adverse event literature is generated from regional anesthesia. Lower extremity blocks do play a significant role for pain practitioners in regards to diagnosis and treatment of chronic pain conditions.

Psoas Compartment Block (Posterior Approach to the Lumbar Plexus)

Because of the anatomic location, blind technique in this region carries the potential for intrathecal injection with resulting total spinal anesthesia, large-volume injections are commonly associated with epidural spread with volumes greater than 20 mL.⁵⁷^–⁶⁰ Peripheral nerve damage and sympathetic block from extravasation of local anesthetic are also reported with the paravertebral approach. Furthermore, case reports exist of retroperitoneal hematomas with associated lumbar plexopathies (Fig. 12-5).⁶¹

Fig. 12-5 A computed tomographic image demonstrating a large retroperitoneal hematoma (arrows) distorting the right psoas muscle.

Lumbar Sympathetic Block

The lumbar sympathetic block is used for a variety of lower extremity sympathetically mediated disorders. Similar to the stellate ganglion block, complications related to this procedure are best characterized as anatomic, drug-related, or infectious. Traversing the lumbar roots for this procedure increases the likelihood of lumbar root injury. Furthermore, the close proximity of the lumbar plexus to major vessels increases the likelihood of vascular puncture.⁶² Anatomic knowledge in combination with image guidance in this region is paramount because injury to vital structures, including renal and ureteral trauma, have been reported.^63,⁶⁴ Furthermore, local anesthetic toxicity and intrathecal blocks have been reported.⁶⁵

Perivascular Three-in-One (Femoral) Nerve Block

Femoral nerve block is frequently used in the perioperative period by regional anesthesiologists for analgesia with total knee replacements.⁶⁶ Complications related to this procedure include intravascular injection, hematoma, and nerve damage, all being reported infrequently.¹³

Lateral Femoral Cutaneous Nerve Block

Meralgia paresthetica is a neurologic disorder of the lateral femoral cutaneous nerve characterized by pain and paresthesia of the anterior lateral thigh. Blockade of the lateral femoral cutaneous nerve is often used more for diagnostic purposes rather than treatment. Complications of this block are rarely reported. It is recommended that ultrasonography be used for this procedure not only to minimize complication but also because of the high incidence of anatomic variation(≤25%).⁶⁷

Sciatic Nerve Block

Again, the sciatic nerve block is more commonly used by regional anesthesiologists than chronic pain practitioners. It is most commonly used for major foot and ankle surgery. It can also be helpful in diagnosis and treatment. Serious complications are rare but include muscle trauma and vascular puncture. Residual dysesthesias are frequently reported and usually last for 1 to 3 days with the remainder usually resolving within several months.^51,⁶⁸ Blockade of the sciatic nerve most commonly occurs in the subgluteal region (Labat approach) or within the popliteal fossa. It is advisable to use ultrasonography to decrease the chance of needle puncture of adjacent vital structures.

Nerve Blocks at the Ankle

Multiple injections may result in discomfort for the patient. Persisting paresthesias may occur but are usually self-limited. Intravascular injection is possible but unlikely if aspiration for blood is negative. There is a low incidence of local anesthetic toxicity with this technique. Because of the small caliber of nerves at this level, blind techniques are most commonly used.

Differential Diagnostic Blocks

Differential diagnostic blocks are used to identify patients’ varying pain complaints and to differentiate among placebo-responsive pain, sympathetic pain, somatic pain, and central pain. The two main approaches to doing a diagnostic differential nerve block are intrathecal and epidural. There are also two techniques, the anatomic approach and the pharmacologic approach. The anatomic approach uses the anatomic separation of somatic and sympathetic nervous system fibers, and the pharmacologic approach uses different concentrations of local anesthetic to affect different types of fibers.⁶⁴

Doing a differential diagnostic block through the epidural approach is generally more time consuming because it takes longer for the blocks to occur and may provide confounding results; however, risks are thought to be decreased with the epidural approach. The complications of performing epidural and spinal differential diagnostic blocks can be related (Box 12-1), the most dreaded being an epidural abscess (Fig. 12-6).^64,⁶⁵

Box 12-1

Data from Hodges SD, Castleberg RL, Miller T, et al: Cervical epidural steroid injection with intrinsic spinal cord damage. Two case reports. Spine (Phila Pa 1976) 23: 1998; Benzon HT: Diagnostic nerve blocks. In Benzon HT, editor: Essentials of pain medicine and regional anesthesia, ed 2, Philadelphia, 2005, Elsevier-Churchill Livingstone; Bromage PR, Benumof JL: Paraplegia following intracord injection during attempted epidural anesthesia under general anesthesia. Reg Anesth Pain Med 23: 1998.

Complications of Differential Diagnostic Block

Direct neural injury

Spinal cord puncture (reports only in sedated or anesthetic patients)

Dural puncture headache

Vasospastic or vasoocclusive (e.g., anterior spinal artery syndrome)

Epidural abscess

Meningitis

Discitis

Fig. 12-6 T1-weighted magnetic resonance image with gadolinium enhancement demonstrating a posterior spinal epidural abscess from C2 to T8 after thoracic epidural catheter insertion.

(From Payer M, Walser H: Evacuation of a 14-vertebral-level cervico-thoracic epidural abscess and review of surgical options for extensive spinal epidural abscesses, J Clin Neurosci 15:483-486, 2008.)