Neurological Complications of Regional Anesthesia in Obstetrics

8/11/2019 Neurological Complications of Regional Anesthesia in Obstetrics

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D R . A B D U L S AT TA R S H A M S U D D I ND E PA RT M E N T O F A N E S T H E S I A

S F H

Neurological complications ofregional anesthesia in obstetrics


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Introduction2


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Introduction

Over 100 years ago August Bier performed the firstrecorded spinal anesthesia and also being the first todescribe the PDPH.Now incidence of PDPH is

decreased due to use of pencil point spinal needlesfrom 25-27 gauge.

Over the last 30 years the Confidential Enquiry into

Maternal Deaths has been responsible for theincreased use of R.A for the C/Section due to itsincreased safety.

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Introduction

For both parturients and anesthesiologists the mostfeared complication of regional anesthesia is aneurological deficit.

Fortunately, neurological deficits are very rare inobstetric patients.

Most neurological injuries are due to obstetrical, notanesthetic causes.

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Introduction

But unfortunatelysurgeons, obstetricians,and even neurologiststended to assume that all

nerve damage afterregional blocks areanesthesia related.

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1. Case Report

The anesthesiologist administered a labor epidural toa 31-year-old female. The baby was delivered vaginally without difficulty, but at postpartum thepatient complained of paresthesia of both lowerextremities.

A neurologist diagnosed bilateral femoral nerveinjury, likely secondary to the positioning of thepatients legs during delivery. . Three weeks afterdelivery, the patient was still under the neurologistscare, but had greatly improved.

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2. Case Report

The anesthesiologist administered a labor epidural toa 30-year-old female.Patient went into prolonglabor, after 10 hours C-section was done,epiduralremoved in OR.

Patient complained numbness in right foot on 1 st post op day.On neurologists advice MRI of back isdone ,result was normal.Patient discharged on day 5 with minimal resedual numbness.Possible causemight be neuropathy due to positioning in prolonglabor.

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Obstetric related neurological deficits 10


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Obstetric related neurological deficits

Parturient who do not receive regional or generalanesthesia may experience compression nerve injury, orrarely, an ischemic spinal cord injury. The incidence of permanent neurological deficits is ashigh as (1.6-4.8/10,000). 2,6,7

Prolong labor and use of forceps contribute tolumbosacral plexus injury.

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The fetal head may also compress and injure thelumbosacral plexus as it crosses the ala of the sacrum orthe posterior brim of the pelvis.

This injury is more common in nulliparous women withplatypelloid pelvises, large babies, cephalopelvicdisproportion, vertex presentation and forcepsdelivery. 2,3 Compressive nerve injuries of this type may involvemultiple root levels and appear as injuries to manynerves.

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Nerve injuries, including numbness and palsies, wereseen in several obstetric cases.

Ultimately, some cases were found to beinconsistent with nerve root damage from epiduralplacement.

Examples included saphenous or peroneal nervecompression from lithotomy stirrups.

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The common peroneal nerve is prone to compressionat the fibular head during positioning in stirrups.

Symptoms include lateral calf paresthesia,dorsalsensory loss between the 1 st and 2 nd toes,along withfoot drop and inversion.


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Femoral nerve injury decreases sensation over theanterior thigh and medial calf and impairsquadriceps strength, hip flexion and patellar reflex.

Proximal lesions at the level of the lumbosacralplexus also may decrease hip flexion due to iliopsoas weakness.

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The obturator nerve can be compressed against thelateral pelvic wall or during its course in theobturator canal. This results in decreased sensationover the medial thigh, weakness of the hip adductorsand decreased ability to internally rotate.

Lateral cutaneous nerve of thigh can be injured by

compression during second stage of labor anddamage is characterized by numbness on theanterolateral aspect of thigh.


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Ischemic injury may also produce neurologicdeficits. The spinal cord may becomeischemic during periods of hypotension or by compression of its blood supply. The anterior part of the lower spinal cord issupplied by either the artery of Adamkiewicz(85%) or a branch of the iliac artery (15%). 8

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The feeder vessels from the iliac artery may becompressed as they cross the lumbosacral trunk.

The artery of Adamkiewicz injury results in theloss of motor function (anterior horn), as well aspain and temperature (spinothalamic tract).

This is known as anterior spinal artery syndrome.


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The dorsal column, which carries vibration and jointsensation, is supplied by the vertebral arteries andare therefore spared.

Arteriovenous malformation within the spinal cordmay also rarely cause paraplegia. The mechanism ofinjury is increased spinal venous pressure, which

predisposes to arterial stasis during periods ofmoderate hypotension or compression.

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Anesthesia related neurological deficits 21


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Anesthesia related neurological deficits

Serious neurological complications related toregional anesthesia are fortunately very rare.

Neurological complications may be due to directnerve trauma, severe hypotension,bradycardia,cardiac arrest, equipment problems, adverse drugeffect, administration of the wrong drug and wrong

site of administration.

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Auroy et al. prospectively monitored neurologiccomplications in more than 103,000 regional anesthetics. 9 All deficits were present within 48 hours after anesthesia.Most (29/34) were transient, with recovery occurring

between 2 days and 3 months.

Spinal anesthesia was significantly more likely to result in both neurologic injury (5.9 vs. 2/10,000) and radiculopathy

(4.7 vs. 1.7/10,000), compared to epidural anesthesia.

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Anesthesia related neurological deficits 25

All radiculopathies resolved except one (spinal). Of the patients who developed deficits withoutparesthesia, 12/13 occurred following spinal

anesthesia. In this series only one patient (who was elderly andexperienced prolonged hypotension) becameparaplegic. 9


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Scott et al monitored 505,000 epidural blocks inparturient, finding only 38 single root neuropathies(0.75/10,000). All deficits resolved by 3 monthsexcept for one. 11

In a similar study involving 123,000 regionalanesthetics in parturient, 46 cases of single nerveroot neuropathy were reported (3.7/10,000), with

complete recovery in all patients by 3 months.12

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Cardiac arrest occurred significantly more commonlyfollowing spinal anesthesia compared to epidural(6.4 vs. 1/10,000).

In obstetric patients, there were 3 cardiac arrests in505,000 epidurals (0.06/10,000). Two patientsrecovered without sequelae and one had braindamage after severe hypotension following a `top-

up'.12

Bupivacaine binds avidly to the sodium channel ,thus cardiac resuscitation is extremely difficult.

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Epidural catheters may rarely break or shear. Cathetersare never to be withdrawn through the needle. If part of acatheter is left in a patient, the patient should beinformed. However, no surgery or attempts to retrieve the catheterare warranted unless there are neurologic symptoms.

Meningitis and Arachnoiditis has also been reportedfollowing neuraxial anesthesia. It may be associated withthe bacteraemia .

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Epidural hematoma is another feared, but rarely seencomplication of regional anesthesia (1/150,000-250,000) in healthy patients. 13

Most epidural hematomas following regional anesthesiaoccurred in patients with hemostatic abnormalities,particularly those on anticoagulants.

Low molecular weight heparins have been responsiblefor over 35 epidural hematomas following regionalanesthesia.

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The symptoms of epidural hematoma are bilateral leg weakness, urinary incontinence and loss of rectalsphincter tone.

These severe neurologic deficits may be preceded bysharp pain in the back or legs with progression over a fewhours. Prolonged motor paralysis without regression of block should raise suspicion.

Stat CT or MRI is indicated. Symptomatic epiduralhematoma must be decompressed surgically within 6hours for the best chance of full recovery

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Epidural abscess is usually due to infection in the bodyseeding the epidural space. In one review, epiduralanesthesia was associated with only in 1 in 39 epiduralabscesses. 14 While epidural anesthesia was unrelated to 35 abscessesin another review. Symptoms of epidural abscess usuallydevelop a few days to a few weeks after delivery.

In a series of over 500,000 epidurals, only one patient(diabetic) developed an abscess, albeit 11 months afterdelivery. 11

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Epidural abscess symptoms include fever, malaise, andheadache and back pain at the level of the infection. Pain will be found on deep palpation over the site.

White blood cell count will be elevated. Progression ofsymptoms to nerve root pain usually takes 1-3 days.

Neurologic deficits will progress as the spinal cord is

compressed including: lower extremity pain, weakness, bowel and bladder dysfunction and paraplegia. Surgicaltreatment is necessary

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Spinal needles may touch nerve roots, or directlyinjure the spinal cord and may cause cauda equenasyndrome.

If the patient reports localized pain with insertion ofan epidural or spinal needle or catheter, stopimmediately!

Anatomic variation may alter landmarks and placenervous tissue at risk for injury.

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Neurological complications of regional anesthesiain obstetrics

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For obstetric and anesthesia related causes ofneurological deficits, a focused history,physicalexamination and laboratory tests are needed toensure proper diagnosis and treatment.


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History

A proper history should focus on the exact onset,location, and radiation of symptoms. Was there pain during needle insertion or injection oflocal anesthetic?

Was there a period of full recovery or was the anesthetic block prolonged? Do the symptoms follow a dermatomal or peripheralnerve pattern?

Items to inquire about specifically related to OB include:leg position (especially during second stage of labor),duration and degree of hyperflexion of the hips, length ofsecond stage and the use of forceps.

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Laboratory tests

The preliminary differential diagnosis will suggest whichtests are needed. If fever accompanies back pain or headache, a white blood cell count and CSF evaluation (septic meningitis)

are needed. If symptoms are isolated to a single nerve root, CT orMRI will be helpful. An occult herniated disc may become symptomatic afterpositioning and pushing during delivery. Any bilateral symptoms or deficits warrant a CT or MRIscan to determine compression by an intraspinal mass(e.g. blood or abscess).

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Laboratory tests

Electrophysiologic testing may also be helpful EMG can help document the time and location of injury. Afterdenervation, muscle fibers begin to discharge spontaneously, butchanges are not seen until 2-3 weeks after injury.

Thus, an abnormal EMG obtained within the first week following aregional anesthetic is useful for determining preexisting disease. If an interval change occurs 4-6 weeks later, then the injuryoccurred around the time of delivery.

Injury at the level of the nerve root should affect both the anteriorand the posterior rami. If the paraspinous area (supplied by theposterior ramus) is not affected, then the level of nerve injury isdistal to the nerve root and not caused by central neuraxialanesthesia.

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Laboratory tests

Nerve conduction-velocity studies can provide immediateinformation about both motor and sensory nerves. Lesions proximal to the dorsal root ganglia do not affect thesensory potential and thus help to distinguish radicular fromperipheral nerve disease.Somatosensory evoked potentials (SSEPs) monitor the dorsalcolumn of the spinal cord and are a key, objective test of sensoryfunction. SSEPs are sensitive to spinal cord damage produced bycompression, mechanical distraction and ischemia. Motor evoked potentials (MEPs) measure the descending motor

pathways in the anterior spinal cord. A magnetic field is used tostimulate the motor cortex with responses measured in theperipheral muscles. Although not widely available, MEPs are asuperb, objective test to assess motor pathways. 5

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Conclusion

In summary, neurologic complications due toregional anesthesia are very rare in obstetricpatients. Although it is more likely that neurologic complaintsare due to factors associated with labor and delivery(1.6-4.8/10000) , it is imperative to explore thepossible deficits related to regional anesthetictechniques (0-1.2/10000).

A careful history, physical exam, laboratory testingand use of imaging techniques will help to ensure anaccurate diagnosis and good outcome.

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References

1.Zakowski MI. Postoperative complications associated with regional anesthesia in the parturient. In Obstetric Anesthesia, 2nd ed. Ed Norris M, Lippincott Williams & Wilkins, Philadelphia, 1999.2.Cole JT. Maternal obstetric paralysis. Am J Obstet Gynecol 1946:52:372-86.3.Graham JG. Neurological complications of pregnancy and anaesthesia. Clin Obstet Gynecol 1982:9:333-504.Chan S et al. CT and MRI. In Rowland LP ed, Merritt's textbook of neurology , Baltimore, Williams &

Witkins, 1995:59-66.5.Lange DJ Trojaborg W. Electromyography and nerve conduction studies in neuromuscular disease. InRowland LP, Ed. Merritt's textbook of neurology , Baltimore, Williams & Witkins, 1995:77.6.Tilleman AJB. Traumatic neuritis in the puerperium. Am J Obstet Gynecol 1935:29:660-67.Holdcroft A et al. Neurological complications associated with pregnancy. Br J Anaesth 1995:75:5228.Lazorthes G et al. La vascularization de la moelle epiniere (etude anatomique et physiologique) Rev Neurol1962:106:535-579.Auroy Y Narchi P, Messiah A, et al Serious complications related to regional anesthesia: results of aprospective survey in France. Anesthesthesiology 1997:87:479-8610.Render CA. The reproducibility of the iliac crest as marker of lumbar spine level. Anaesthesia 1996:51:107011.Scott DB Hibbard BM. Serious non-fatal complications associated with extradural block in obstetricpractice. Br J Anaesth 1990:64:537-41.12.Scott DB Tunstall ME Serious complications associated with epidural/spinal blockade in obsterics: a two-

year prospective study. Int J Obstet Aanesth 1995:4:133-9.13.Horlocker TT Regional anesthesia and analgesia in the patient receiving thromboprophylaxis. [editorial]Reg Anesth 1996:21:503-7.14.Baker AS et al. Spinal epidural abscess. N Engl J Med 1975:293:463

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Neurological Complications of Regional Anesthesia in Obstetrics

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