Neurologic complications - whom to blame ?

Benno Rehberg Médecin adjoint agrégé

Unité d’anesthésiologie gynéco-obstétricale, HUG

SAOA spring meeting 2015

The simple surgical answer:

outline • Epidemiology

• Mechanisms

• Prognosis

• Work-up

Not included: - Local anesthetic toxicity - Transient neurologic symptoms due to hyperbaric solutions

EPIDEMIOLOGY – LET THE NUMBERS SPEAK

Rising liability claims of neurologic injury in obstetric anesthesia

Paraplegia: 4 epidural hematoma 4 epidural abscess 2 direct spinal cord injections 1 anterior spinal artery syndrome

Davies, J. M et al: Liability associated with obstetric anesthesia: a closed claims analysis. Anesthesiology 110, 131–139 (2009).

What is the real risk?

1 / 100

1 / 10.000

1 / 1.000

1 / 100.000

Incidence of postpartum neuropathy 1/100

Wong, C. A. Obstet Gynecol 101, 279–288 (2003).

Incidence of permanent harm after neuraxial block in obstetrics: 1.2/100.000

Cook T et al: Br J Anaesth 102, 179–190 (2009)

Incidence of radiculopathy after spinal or epidural anesthesia: 2-4/10.000

Brull, R., et al: Anesth. Analg. 104, 965–974 (2007).

Incidence of postpartum lumbosacral spine and lower extremity nerve injuries

• Prospective study spanning 1 year (1997-98): 6057 patients

• Question at day 1 after delivery: «Do you have any leg numbness or weakness?»

• n= 6048

• If positive answer, neurological examination by a physiatrist

Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279–288 (2003).

Incidence of postpartum lumbosacral spine and lower extremity nerve injuries

Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279–288 (2003).

Elective C-section

Risk factors for postpartum neurological injury

• Nulliparity

• Prolonged second stage of labor

Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279–288 (2003).

= odds ratio

suspected = clinical examination or other studies not available

Which type of injury is common?

Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279–288 (2003).

n = 6048

MECHANISMS OF OBSTRETIC NERVE INJURY - WHAT HAPPENS IN 95% OF CASES

Mechanism of lesion: Lateral femoral cutaneous nerve

• Compression against the inguinal ligament

– During pregnancy (after 30 weeks)

– Prolonged hip flexion

– Due to retraction during c-section

• Diabetes is a risk factor (for all nerve compression injuries)

Lateral femoral cutaneous nerve

«meralgia paresthetica»: - numbness - paresthesia

Innervation sensory motor

-----

Mechanism of lesion: Femoral nerve

• Compression against the inguinal ligament – During thigh flexion,

external rotation and abduction (position for pushing)

• Nerve entrapment in the psoas muscle

• Compression of the saphenous nerve at the knee

L2, L3, L4

Femoral nerve Innervation

sensory motor

- M. iliopsoas - M. quadriceps

L2, L3, L4

Extension: Saphenous nerve

Diminished patellar reflex, difficulties hip flexion

25% bilateral!

Mechanism of lesion: obturator nerve

• Compression between pelvis and fœtal head

– Lithotomy position

– Forceps

L2, L3, L4

Obturator nerve Innervation

sensory motor

- M. adductor

L2, L3, L4

Weakness of tigh adduction, abnormal gait

Mechanism of lesion: Lumbosacral plexus

L5-S4

• Compression between pelvis and fœtal head

– Macrosomia

– Forceps /vacuum

• Sciatic nerve: rare

• Peroneal nerve:

– External compression at the knee

Lumbosacral plexus Innervation

sensory motor

- M. quadriceps - M. adducteur L5-S4

Foot drop, difficulties of hip flexion and hip adduction

Saphenous n. Sural n.

Deficit highly variable!

Potentially also anal sphincter dysfunction

And what about radiculopathy?

Brull, R., McCartney, C. J. L., Chan, V. W. S. & El-Beheiry, H. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth. Analg. 104, 965–974 (2007).

And what about radiculopathy?

Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279–288 (2003).

N = 6048

And what about radiculopathy?

• Associated with anesthesia in retrospective studies:

– In 17 of 24 cases of radiculopathy, there was paresthesia during puncture of pain during injection (Auroy 1997)

– All radicular deficits recovered except for one deficit which ocurred after spinal anesthesia without any paresthesia or pain

Auroy, Y. et al. Serious complications related to regional anesthesia: results of a prospective survey in France. Anesthesiology 87, 479–486 (1997).

OUTCOME / PROGNOSIS

Recovery depends on severity of nerve injury

Severity of injury Predicted recovery

• Remyelination: 2-12 weeks

• Collateral sprouting and axonal regeneration: 2-6 months

• No recovery or partial axonal regeneration: 2-18 months

Neurapraxia

Axonotmesis

Neurotmesis

Duration of postpartum neurological symptoms

Wong, C. A. et al. Obstet Gynecol 101, 279–288 (2003).

WORK-UP: HOW TO FIND OUT WHO IS TO BLAME

Step 1: rule out serious problems

• Progression of symptoms?

• Fever?

• Back pain?

• Cauda/conus symptoms?

• Neck stiffness? Kernig sign? (pain on knee

extension with flexed hip)

• Laboratory signs of infection?

• Epidural hematoma

• Epidural abscess

• Meningitis

Step 2: history & physical exam

• Mode of delivery?

• Duration of second stage of labour?

• Positioning during pushing

• Preexisting neurological problems?

• Intact sensation on the lower back (innervated by posterior rami) rules against central lesion

• Central lesions are more often accompanied by back pain

Step 3: central vs peripheral lesion

Central lesion Peripheral nerve lesion

• Sensory (and motor deficit) corresponds to peripheral nerve

• Tinel’s sign positive (pain or paresthesia when tapping on the injured part of the nerve) in peripheral lesion

• Affection of multiple nerve roots without back pain or other signs of serious problems is almost never a central problem

Step 3: central vs peripheral lesion

Wong, C. A. Nerve injuries after neuraxial anaesthesia and their medicolegal implications. Best Pract Res Clin Obstet Gynaecol 24, 367–381 (2010).

Central lesion Peripheral nerve lesion

Step 4: further studies

A) imaging: MRI

– Indicated if epidural hematoma/abscess is suspected

– May be indicated if signs of central lesion are present, such as Lhermitte’s sign (neck flexion causing

shooting pain in the back, sign of irritation of the posterior column of the spinal cord)

Step 4: further studies

B) Electrodiagnostic studies: to determine prognosis of a peripheral nerve injury, they should be performed with a delay of 10-21 days (earlier only to rule out preexisting deficits)

Wallerian degeneration takes 1-2 weeks to develop, then it shows typical signs of denervation in the ENMG

Step 4: further studies

B) Electrodiagnostic studies:

- indicated to determine prognosis related to axonal loss (=extent of denervation signs)

- cannot differentiate between radiculopathy and plexopathy (L2, L3 and L4 roots have extensive myotomal overlap, paraspinal muscles can be normal in radiculopathy and abnormal in plexopathy)

Conclusion

• In most cases, history &physical examination are clearly indicative of a peripheral nerve lesion

• In some cases, electrodiagnostic studies and MRI help to identify the peripheral lesion

• In rare cases, the differentiation of plexopathy vs radiculopathy is not possible

Thank you for your attention!

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