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Prolonged block

A woman underwent elective caesarean section under spinal anaesthesia. The spinal had been inserted easily on the first pass and 2.6 mL 0.5% heavy bupivacaine with 300 mcg prefilled diamorphine administered.

The patient was reviewed by a consultant anaesthetist postoperatively because of prolonged motor block, and an MRI of the lumbar spine was arranged to rule out cord compression. Further imaging over the weekend included CT head and MRI head, both reported as normal. A neurology review was requested but did not occur until the following day.

Over the weekend, lower limb movement remained restricted and there was decreased sensation in L4, L5, and S1 dermatomes. Plans were made for trial without catheter and attempts to mobilise.

Commentary

Regression of neuraxial block can be extremely variable.1 However, an early sign of a space occupying lesion in the neuraxis is prolonged or increasing motor block and there is only limited time before neurological deficit becomes permanent. Association of Anaesthetist guidelines suggest that inability to straight leg raise that persists beyond 4 hours should trigger review.2 Rapid 24/7 access to MRI scanning should be available in all units where neuraxial blocks are undertaken.3,4 SALG endorses the use of a local anaesthetic alert  wrist band documenting a time by which the patient should be able to lift their legs and asking the patient to alert staff if they are unable to do so.

References

  1. Roderick E, Hoyle J, Yentis SM. A national survey of neurological monitoring practice after obstetric regional anaesthesia in the UK. Anaes. 2017; 72(6): 755-759 doi:10.1111/anae.13800
  2. Yentis SM, Lucas DN, Brigante L, Collis, R et al. Safety guideline: neurological monitoring associated with obstetric neuraxial block. Anaes. 2020; 75(7): 913-19 doi:10.1111/anae.14993
  3. Royal College of Anaesthetists. Guidelines for the Provision of Anaesthetic Services in the non-theatre environment. 2025 [Available: https://www.rcoa.ac.uk/chapter-7]
  4. Royal College of Anaesthetists. Anaesthesia Clinical Services Accreditation (ACSA) Standard 1.1.1.7 [Available: https://www.rcoa.ac.uk/media/48806]
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