Eye Problem Following Foot Surgery – Abducens Palsy as a Complication of Spinal Anesthesia

Abstract and Introduction

Abstract

Background

Paralysis of abducens nerve is a very rare complication of lumbar puncture, which is a common procedure most often used for diagnostic and anesthetic purposes.

Case Report

A 38-year-old man underwent surgery for a left hallux valgus while he was under spinal anesthesia. On the first postoperative day, the patient experienced a severe headache that did not respond to standard nonsteroidal anti-inflammatory medication and hydration. During the second postoperative day, nausea and vomiting occurred. On the fourth postoperative day, nausea ceased completely but the patient complained of diplopia. Examination revealed bilateral strabismus with bilateral abducens nerve palsy. His diplopia resolved completely after 9 weeks and strabismus after 6 months.

Conclusion

Abducens palsy following spinal anesthesia is a rare and reversible complication. Spinal anesthesia is still a feasible procedure for both the orthopaedic surgeon and the patient. Other types of anesthesia or performing spinal anesthesia with smaller diameter or atraumatic spinal needles may help decrease the incidence of abducens palsy. Informing the patient about the reversibility of the complication is essential during the follow-up because the palsy may last for as long as 6 months. Special attention must be paid to patient positioning following the operation. Recumbency and lying flat should be accomplished as soon as possible to prevent cerebrospinal fluid leakage and resultant intracranial hypotension. This becomes much more important if the patient has postdural puncture headache.

Introduction

Lumbar puncture (LP) is a common procedure most often used for diagnostic and anesthetic purposes. The most common side effect of lumbar puncture is post-lumbar puncture headache (PLPH), which is due to cerebrospinal fluid (CSF) hypotension resulting from persistent spinal fluid leakage from the puncture site.[1–3] Frequency of PLPH is less than 1% to 2% in skilled hands.[4]

Injuries of the fourth and sixth cranial nerves have been reported after LP usually combined with PLPH.[1,4–7] There is no uniform definition of severe PLPH. But a widely accepted definition is: a constant headache appearing or worsening significantly upon assuming the upright position and resolving or improving significantly upon lying down.[8]

The importance of this pattern of headache is that it usually develops before the onset of paralysis of the abducens nerve,[1,4–7] which is the most commonly affected nerve.[1,6] Besides the diagnostic LP, epidural and spinal anesthesia, myelography, and ventricular shunting for hydrocephalus may also lead to abducens nerve palsies.[1,4–7,9]

Risk of abducens palsy after LP is not definite. A study by Thomke and colleagues report it to be 1 in 5800,[3] and Follens and colleagues[6] report that the incidence is 1 in 400. The incidence of abducens palsy after myelography is 1 in 500 cases.[4] Abducens palsy after LP can be unilateral or bilateral.[1,6] It usually occurs 4-14 days after LP and resolves completely after 4 weeks to 4 months.[1,3–7,9] We report a case of abducens nerve palsy following spinal anesthesia.

Case Report

A 38-year-old man presented to our clinic with a 4-year history of pain and deformity of the first metatarsophalangeal joint of his left foot. His examination revealed a left hallux valgus with ulceration of the skin overlying the bunion deformity. His hallux valgus angle was 34 degrees and the intermetatarsal angle was 8 on the AP x-ray. The joint was congruent and there was no evidence of arthrosis. Correction via modified Chevron procedure with a capsuloperiosteal flap was planned and performed with the patient under spinal anesthesia. The patient's medical history was insignificant regarding systemic illnesses and was accepted as ASA1 class before to the application of anesthesia.

Spinal anesthesia was administered in one attempt through the L2-L3 intervertebral space while the patient was in a lateral recumbent position with a 22-gauge Quincke-type spinal needle with no complications. The CSF was clear without visible blood. The analgesia lasted for 2 hours postoperatively and after that period analgesic medication was continued with nonsteroidal anti-inflammatory drug injections and oral paracetamol tablets every 6 hours. The patient's general condition (neurologic status, vital signs, hemodynamics) was stable during the preoperative and postoperative periods. He was given 1500 cc isotonic NaCl IV solution during the operation. His urine output was not monitored.

On the first postoperative day, the patient experienced a severe headache that did not respond to the standard nonsteroidal analgesic medication and hydration. His daily oral fluid intake was approximately 2000 mL. Despite his headache, he was not told to lie down or keep a recumbent position until the end of the second postoperative day. During the second postoperative day, he experienced nausea and vomited 3 times. The nausea and vomiting did not respond to antiemetic medication, but responded well when the patient was placed on his back on the third postoperative day.

On the fourth postoperative day, the patient's nausea ceased completely, but he complained of diplopia (double vision), and his examination revealed bilateral strabismus. When he was told to make a lateral gaze after covering one of his eyes; he was unable to do this procedure with both of his eyes. His overall condition, vital signs, and neurologic status were normal. An ophthalmology consult was obtained. Bilateral abducens nerve palsy was diagnosed, which was clinically evident but the optic disc and field of vision were normal. He was given intermittent eye closure and lateral gaze exercises. Cranial magnetic resonance imaging (MRI), which was obtained to exclude an intracranial pathology, was normal.

The patient was given nonsteroidal anti-inflammatory medication and steroids to decrease neural edema (prednisolone 16-mg tablet decreased to half by 2-day intervals and stopped on the eighth day). The disorder did not respond to this treatment.

The patient returned to work after 9 weeks. His diplopia was minimized at the end of sixth week but did not resolve completely until the end of the ninth week. At that time, he still had mild strabismus. His strabismus had decreased to a minimal level at the end of 16th week and completely resolved at the end of 6 months.

Discussion

Post-LP complaints may also be called the syndrome of intracranial hypotension, which encompasses a triad of headache, ear problems, and ocular symptoms.[6]

Differential diagnosis of sixth nerve palsy includes neoplasms, infiltrative and inflammatory lesions, infection, and vascular lesions.[6] Late onset of the palsy associated with nausea and headache suggests overdrainage of the CSF with consequent traction on the nerve.[9]

Large series indicate that the incidence of PLPH and other central nervous system-related side effects of LP depend on age, sex, and the diameter and shape of needle. Smaller needles produce PLPH less often than larger needles of the same shape.[1,3,8] In our patient we had to use a Quincke type spinal needle because relatively atraumatic Sprott or Whitacre needles or smaller Quincke needles (like 25G) were not available in our institution.

Multiple insertions of the needle into the subarachnoid space may also be a possible cause of PLPH and abducens palsy.[7] Younger age and female gender are definite risk factors.[8]

Risk of abducens palsy after LP is not definite. A study of Thomke and colleagues report the risk to be 1 in 5800,[3] and Follens and colleagues report an incidence of 1 in 400.[6] The incidence of abducens palsy after myelography is 1 in 500 cases.[4] Abducens palsy after LP can be unilateral or bilateral.[1,6] It usually occurs 4-14 days after LP and resolves completely after 4 weeks to 4 months.[1,3–7,9] Our case was the first, among 12.785 spinal anesthesias performed in the past 6 years (.0078%). It is also unique in its duration, which was about 6 months. To our knowledge, this is the longest duration in the English literature.

Treatments for PLPH once it has occurred include oral or IV caffeine, epidural saline, and epidural blood patches.[2,8] An epidural blood patch, although effective in treating PLPH, is ineffective in preventing the occurrence of abducens nerve palsy when performed at the onset of double vision.[4,10] MRI can be used both to determine the site of CSF leakage and for accurate placement of the blood patch.[2]

Conclusion

Abducens palsy following spinal anesthesia is a rare and reversible complication. Spinal anesthesia is still a feasible choice for both the orthopaedic surgeon and the patient. But to decrease the incidence of this complication, other types of anesthesia may also be used (such as general with laryngeal mask, peripheral nerve block with sedation, etc). If this complication occurs, patience and informing the patient about reversibility are essential during the follow-up, because the palsy may last as long as 6 months.

Atraumatic needles with side holes such as Sprott or Whitacre needles or smaller dimension Quincke type needles may be used during spinal anesthesia to decrease the incidence of PLPH.

Special attention must be paid to patient positioning following the operation. Recumbency and lying flat should be accomplished as soon as possible to prevent CSF leakage and resultant intracranial hypotension. This becomes much more important if the patient has postdural puncture headache.

Epidural blood patching can be routinely applied if large needles are used, and if multiple needle insertions are made to the subarachnoid region, because these may increase the incidence of both PLPH and abducens palsy.

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