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 Incidence of postpartum neuropathy 1/100 Wong, C. A. Obstet Gynecol 101, 279 288 (2003). 1 / 1.000 1 / 10.000 Incidence of radiculopathy after spinal or epidural anesthesia: 2-4/10.000 Brull, R., et al: Anesth. Analg. 104, 965 974 (2007). 1 / 100.000 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 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 Elective C-section Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279 288 (2003).
Risk factors for postpartum neurological injury Nulliparity Prolonged second stage of labor = odds ratio suspected = clinical examination or other studies not available Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279 288 (2003).
Which type of injury is common? n = 6048 Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279 288 (2003).
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 sensory Innervation «meralgia paresthetica»: - numbness - paresthesia motor -----
L2, L3, L4 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
Femoral nerve sensory Innervation motor L2, L3, L4 - M. iliopsoas - M. quadriceps Diminished patellar reflex, difficulties hip flexion Extension: Saphenous nerve 25% bilateral!
Mechanism of lesion: obturator nerve L2, L3, L4 Compression between pelvis and fœtal head Lithotomy position Forceps
Obturator nerve sensory Innervation 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 sensory Innervation motor L5-S4 - M. quadriceps - M. adducteur Deficit highly variable! Foot drop, difficulties of hip flexion and hip adduction Saphenous n. Sural n. 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? N = 6048 Wong, C. A. et al. Incidence of postpartum lumbosacral spine and lower extremity nerve injuries. Obstet Gynecol 101, 279 288 (2003).
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 Neurapraxia Remyelination: 2-12 weeks Axonotmesis Neurotmesis Collateral sprouting and axonal regeneration: 2-6 months No recovery or partial axonal regeneration: 2-18 months
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 Affection of multiple nerve roots without back pain or other signs of serious problems is almost never a central problem Tinel s sign positive (pain or paresthesia when tapping on the injured part of the nerve) in peripheral lesion
Step 3: central vs peripheral lesion Central lesion Peripheral nerve lesion Wong, C. A. Nerve injuries after neuraxial anaesthesia and their medicolegal implications. Best Pract Res Clin Obstet Gynaecol 24, 367 381 (2010).
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
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