Paravertebral Block

Chapter 12 Paravertebral Block



Sang-Sik Choi, MD, Mi-Guem Lee, MD, Mi-Kyung Lee, MD, PhD


The paravertebral space does not naturally exist. It is a potential space that can be created by fluid distention. If fluid (e.g., local anesthetics) is injected, it will distend and open a wedge-shaped space [1]. The boundaries of the paravertebral space are described in Table 12.1. Lumbar paravertebral block (PVB) is also known as lumbar plexus block and psoas compartment block.


Table 12.1 Boundaries of the Paravertebral Space





















Posterior
Superior costotransverse ligament

Laterally to the posterior intercostal membrane
Anterior Parietal pleura
Medial Posterolateral aspect of the vertebra, intervertebral disc, intervertebral foramen
Superior Occiput
Inferior Alar of the sacrum
Lateral No limit; contiguous with the intercostal space

From Richardson J. Paravertebral anesthesia and analgesia. Can J Anaesth 2004;51:R1-R6.


Local anesthetics injected in this area will bathe the following neurologic structures: the anterior and posterior rami of the spinal nerve, and the white and gray rami communicantes. In the thoracic region, the sympathetic chain is exposed to injectate because it is located laterally to the vertebral body, not anterolaterally as in the lumbar region. In the lumbar region, the sympathetic chain may not be involved because it is separated from more posterior structures arising from the intervertebral foramen by the iliopsoas muscle, which originates from the lateral vertebral bodies (Table 12.2; Figs. 10-10 and 10-11)[1–4]. The sacral spine cannot be subjected to PVB owing to the fusion of the transverse processes to form the lateral mass.


Table 12.2 Potential Tracking of Injectate from Deposition within the Paravertebral Space















Superior and inferior
Within the paravertebral gutter

In the thorax across the heads and necks of the ribs
Medial Through the intervertebral foramen (epidural anesthesia)
Lateral Contribution to cervical, stellate ganglion, brachial plexus, intercostal and lumbar plexus blockade
Anterior Not possible unless pleura is breached

From Richardson J. Paravertebral anesthesia and analgesia. Can J Anaesth 2004;51:R1-R6.


In a study of patients with chronic pain undergoing PVB with 15 mL of 0.5% bupivacaine, a mean somatic block of five dermatomes was accompanied by a mean sympathetic block of eight dermatomes, as evidenced by thermographic detection of ipsilateral skin warming[5]. Combinations of local anesthetics with adjuncts such as opiates and clonidine may also be very helpful in improving the quality and duration of the nerve block.


The dose of local anesthetics required involves a consideration of the number of dermatomes to block. Continuous infusion provides better analgesia than intermittent bolus doses[1,6].



Lumbar paravertebral block


Lumbar PVB is a favorable choice for selective anesthesia or analgesia of one leg. Lumbar PVB anesthetizes the plexus at its origin, achieving blockade of all branches of the lumbar plexus (femoral, lateral femoral cutaneous, obturator, and genitofemoral). Lumbar PVB allows early ambulation, enabling effective physiotherapy and early discharge. In addition, lumbar PVB is not associated with hemodynamic changes or urinary retention, which would require labor-intensive postoperative care.


Many different methods have been developed for performing posterior lumbar PVB. A loss-of-resistance (LOR) technique using air or saline or an approach using a peripheral nerve stimulator is usually employed to confirm correct placement of the needle within the paravertebral space or psoas compartment. However, these blind blocks are time-consuming and inconvenient to both the patient and the physician. In addition, lumbar PVB cannot be reliably confirmed through the use of only the LOR technique with air or saline; this deficiency can be overcome, however, with the use of C-arm (fluoroscopy) guidance during lumbar PVB in addition to LOR with air or saline.



Thoracic paravertebral block


Thoracic PVB is the technique of injecting local anesthetic adjacent to the thoracic vertebra close to where the spinal nerves emerge from the intervertebral foramina. This maneuver results in ipsilateral somatic and sympathetic nerve blockade in multiple contiguous thoracic dermatomes above and below the site of injection. It is effective in treating acute and chronic pain of unilateral origin from the chest and abdomen. Bilateral use of thoracic PVB has also been described.



Treatment objectives


The treatment objectives of paravertebral blocks are to relieve pain and to improve quality of life. The goals are to provide an early return to physical functioning and work, to restore the ability to perform daily activities, and to allow for recreation.



Indications


The indications for paravertebral block vary with the location of the block [1–3,6–16].



Lumbar Paravertebral Block


Indications for lumbar PVB are as follows:


image Anesthesia and the management of pain associated with unilateral lower limb surgery

image Peripheral vascular disease, such as atherosclerosis obliterans or thromboangiitis obliterans

image Postherpetic neuralgia

It may also be used in patients undergoing anticoagulation therapy in whom neuraxial block is contraindicated.



Thoracic Paravertebral Block


Thoracic PVB is performed for the following indications (Box 12.1):


image Unilateral surgical procedures, such as thoracotomy, breast surgery, cholecystectomy, cardiac surgery, and renal or ureteric surgery

image Analgesia for rib trauma and herniorrhaphy

image Bilaterally in thoracic surgery and major abdominal vascular surgery

image For management of herpes zoster pain, post-mastectomy pain, post-thoracotomy pain, chronic abdominal pain, chronic inguinal pain, benign or malignant neuralgia, complex regional pain syndromes with a sympathetic component, vascular insufficiency, and differential nerve blockade

image Hyperhidrosis

image As an adjunct to interscalene block for major shoulder procedures

image For bone harvesting from the iliac crest

image Obstetric analgesia


BOX 12.1 Reported Indications for Thoracic Paravertebral Block


Adapted from Karmakar MK. Thoracic paravertebral block. Anesthesiology 2001;95:771-780.


As postoperative analgesia for:


Thoracic surgery

Breast surgery

Cholecystectomy

Renal and ureteric surgery

Herniorrhaphy

Video-assisted thoracoscopic surgery

Minimally invasive cardiac surgery

As surgical anesthesia during:


Breast surgery

Herniorrhaphy

Chest wound exploration in a patient receiving a single lung transplant

For acute postherpetic neuralgia


As chronic pain management in benign and malignant neuralgia


For fractured ribs


In therapeutic control of hyperhidrosis


For liver capsule pain after blunt abdominal trauma



Contraindications


Contraindications to lumbar or thoracic PVB may be classified as absolute and relative [1–3,12].


Absolute contraindications are as follows:


image Patient refusal

image Skin infection at the injection site

image Allergy to local anesthetics and contrast agents

image Occupation of the paravertebral space by tumor

Relative contraindications to PVB are as follows:


image A coagulation disorder or the use of anticoagulants; however, the neurologic consequences of a paravertebral hematoma are negligible

image Empyema between the pleurae; the accompanying acidosis and hyperemia may cause systemic local anesthetics toxicity

image Sepsis

image Severe chest deformity or scoliosis, due to the possibility of injection into the meninges or pleura

A planned pleurectomy is not a contraindication to thoracic PVB.



Complications


The overall incidence of side effects or complications of thoracic or lumbar PVB is less than 5%; complications are as follows [1–3,17]:


image Hypotension, which is unusual and has multifactorial causes; it usually involves the unmasking of relative hypovolemia by unilateral vasodilatation

image Acute cardiac or neurologic toxicity caused by accidental intravascular injection

image Pleural puncture

image Pneumothorax

image Neurologic or hemodynamic events due to accidental epidural or intrathecal injection (Figs. 12-1 and 12-2)

image Infection (epidural abscess, meningitis, etc.)

image Renal subcapsular hematoma

image Vasovagal response

image Horner’s syndrome

image Dyspnea

image Superficial skin infection

image Posterior neck pain

image Subclavian artery puncture

image Epidural spread of anesthetic

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Aug 5, 2016 | Posted by in NEUROSURGERY | Comments Off on Paravertebral Block

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