Q4 LONG ANSWER 10M ★ High-yield

Describe Complications of Neuraxial Anaesthesia in detail.

General Surgery · Final Professional

Overview

Complications of neuraxial (spinal/epidural) anaesthesia range from common and self-limiting to rare and catastrophic. They are grouped into physiological effects, technique-related problems, and neurological complications.

Cardiovascular & Respiratory

Hypotension (from sympathetic blockade and vasodilatation) is the commonest effect, with bradycardia if the block is high (blocking the cardiac sympathetic fibres, T1–T4) — treated with fluids, vasopressors (ephedrine/phenylephrine) and, for bradycardia, atropine. A block ascending too high causes respiratory difficulty and, at the extreme, a total spinal (apnoea, profound hypotension, unconsciousness).

Post-dural Puncture Headache & Others

Post-dural puncture headache (PDPH) follows CSF leak through the dural hole — a characteristic postural headache (worse upright). Urinary retention, backache, shivering, nausea (from hypotension), and high/total spinal also occur. With epidurals, accidental dural puncture or intravascular injection may occur.

Neurological Complications

Rare but serious: epidural haematoma (especially with anticoagulation — causing cord compression) and epidural abscess (infection) — both present with progressive weakness, sensory loss and bladder/bowel dysfunction and are surgical emergencies needing urgent imaging and decompression. Direct nerve or cord injury and, very rarely, meningitis or arachnoiditis can occur.

DANGER / REMEMBER

Progressive weakness, back pain and bladder dysfunction after a neuraxial block suggest an epidural haematoma or abscess compressing the cord — a surgical emergency. Urgent MRI and decompression are needed to avoid permanent paralysis; delay costs recovery.

CLINICAL PEARL

Separate the common from the catastrophic: hypotension, PDPH, retention and backache are common/manageable; total spinal, epidural haematoma and abscess are the emergencies. New or worsening neurology after a block demands urgent MRI.

Detecting & Preventing Complications

Because several neuraxial complications are both serious and time-critical, their early detection is built into routine care: blood pressure and heart rate are monitored closely for the expected hypotension and bradycardia, the block height is checked to catch an ascending or total spinal, and the patient’s lower-limb power and bladder function are followed after the block wears off so that a developing haematoma or abscess is not missed. Prevention rests on aseptic technique, correct patient selection with attention to coagulation, careful dosing and, for epidurals, a test dose and incremental injection; and any unexpected, prolonged or progressive neurological deficit is investigated urgently rather than attributed to a slowly-resolving block.

Backache, Retention & Minor Effects

Alongside the dramatic complications, a set of minor and common effects deserve mention because they affect many patients:

backache at the injection site is frequent and usually self-limiting
urinary retention is common because the sacral nerves controlling bladder function are blocked, and may require temporary catheterisation
shivering and nausea (often secondary to hypotension) are frequent
postoperative failure or patchiness of the block may need supplementation. These are rarely serious but are important for consent and for patient comfort, and their recognition prevents them from being mistaken for something more sinister.

CLINICAL PEARL

Sort the complications into common-and-manageable (hypotension, PDPH, retention, backache, shivering) and rare-but-catastrophic (total spinal, epidural haematoma, abscess) — and treat any progressive post-block neurology as cord compression needing urgent MRI.

DANGER / REMEMBER

The unforgivable error is to attribute a prolonged or worsening motor and sensory deficit, back pain or bladder dysfunction to a slowly-resolving block: after the expected recovery time these signal a haematoma or abscess compressing the cord, and only urgent MRI and decompression preserve the chance of recovery.

Hypotension from sympathetic block is the commonest.

Timing	Complication
Immediate	Hypotension, bradycardia, total spinal, LA toxicity
Early	Post-dural puncture headache, urinary retention, backache
Late / serious	Vertebral canal haematoma, epidural abscess, meningitis, nerve injury

KEY POINT

Key points TO remember

Hypotension (sympathetic block) commonest; bradycardia if high (T1–T4) → fluids, vasopressors, atropine.
PDPH (postural headache from CSF leak); retention, backache, shivering, nausea; high/total spinal.
Total spinal: apnoea, profound hypotension, unconsciousness — support airway/circulation.
Epidural haematoma (anticoagulation) & abscess → cord compression: weakness, sensory loss, bladder — urgent MRI/decompression.
New/progressive neurology after a block = emergency until proven otherwise.

EXAM TIP

Sources: Morgan & Mikhail’s Clinical Anesthesiology; Miller’s Anesthesia; Ajay Yadav’s Short Textbook of Anaesthesia.

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