Postoperative Complication of Periocular Anesthesia

7/29/2019 Postoperative Complication of Periocular Anesthesia

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-Postoperative Complications

of Periocular Anesthesia

Ignatius C. Cyriac, M.D.

Roberto Pineda, II, M.D.

Even as current trends move away from retrobulbar blocks and topical

anesthesia gains greater widespread acceptance, ocular anesthesia still is most

commonly administered with a needle. Although rare, numerous complications

associated with the administration of periocular anesthesia have been described,

ranging from the innocuous hemorrhage to life threatening systemic situations.Early recognition is paramount, and judi cious management of these

complications can result in more favorable visual outcomes and significantly less

morbidity.

The local anesthetic ocular complications that are reviewed include

retrobulbar hemorrhage, globe perforation, optic nerve trauma, and mus cl

injury. As systemic complications can be associated with direct central nervous

system (eNS) spread of anesthetic, signs and symptoms of this situation also are

addressed.

Techniques

The aim of retrobulbar anesthesia administration is to direct the tip of theretrobulbar needle toward the orbital apex within the muscle cone to allow

diffusion of anesthetic within this space. When the ocular motor nerves (III and

VI) and sensory nerves (V) are blocked, akinesia and anesthesia is achieved.

Ophthalmic surgery has been performed with local anesthesia for more than

100 years. Herman Knapp was the first to describe retrobulbar anesthesia with

cocaine in 1848. However this method fell into disrepute because of serious and

fatal complications. The modern technique of retrobulbar anesthesia using

lidocaine was described by Atkinson in 1948. This technique of retrobulbar

anesthesia as described by Atkinson has undergone various modifications in

general use but essentially is un-

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86 Cyriac Q,~ Pineda

changed from his original method. Atkinson originally recommended the

technique of positioning the globe in an up and inward gaze using a blunted

needle of no longer than 35 mm. Because of the blind approach of this

technique, Unsold and associates' performed studies that involved scanning

orbits of cadavers after introducing a retrobulbar needle. They demonstrated

the optic nerve, ophthalmic artery, superior orbital vein, and posterior pole of

the globe to be in close proximity to the needle. The authors recommended

placing the globe in primary position or in a down and outward gaze,

suggesting that the optic nerve, vessels, and inferior oblique are placed outside

the path of the anesthetic needle.

Peribulbar anesthesia administration seeks to avoid the optic nerve,

ophthalmic artery and vein, and posterior globe by placing the anesthesia

outside the retrobulbar space just posterior to the equator. Akinesia and

anesthesia is achieved through diffusion of anesthesia in this area. The actual

technique is more varied in its use than is the retrobulbar method of

administration. The technique described by Davis and Mandel/ serves as

representative example of this block. With the eye in primary position, a 12-

mm 27-gauge needle injects a diluted 1 % lidocaine solution into the anteriororbit inferotemporally. In this same area, an 18 to 24-mm 23 to 26-gauge

needle is used to inject a solution of lidocaine, marcaine, and wydase.

Supplemental blocks of this same preparation are administered into the

superonasal or inferonasal orbit as needed.

Peribulbar anesthesia has been believed to be less painful and to result infewer postoperative complications than is retrobulbar anesthesia. Fewer cases

of retrobulbar hemorrhage, globe perforation, and brainstem anesthesia have

been reported.f

Anatomical Considerations

To understand the mechanisms of complications from periocular nerve

blocks first requires knowledge of orbital anatomy. Motor nerves (cranial

nerves III, IV, and VI) insert into rectus muscles between the pos terior and

middle thirds of the muscle belly. Thus, the muscular branches of the third

nerve may be blocked within the muscle cone in the posterior orbit, notably in

the area of the optic nerve and ophthalmic vein, whereas the inferior oblique'snervous and vascular branches insert more anteri orly on the muscle and,

therefore, are more susceptible to damage by blocks provided along the orbital

floor. The origin of the superior oblique in the posterior-superotemporal orbit

and its relative immobility render superotemporal blocks perilous.

Needle length with relation to anatomical dimensions also can increase the

risk of complications for a particular block. It has been shown that the average

length from the lateral one-third of the inferior orbital rim to the orbital apex is

48 mm or less. 4 Also, the intracanalicular portion


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Complications of Periocular , nosia - 87

of the optic nerve is relatively immobile and extends anteriorly from here. Risk

from using long needles then becomes apparent. Using blunt needles was

thought to resolve this risk, but complications have been reported with blunt

needles as well. 5

Local Complications

Hemorrhage

The most common complication of periocular anesthetic administra tion i

retrobulbar and periocular hemorrhage. Incidence of hemor rhages with

retrobulbar blocks is between 1 and 3% and, when combined with peribulbar

blocks, incidences of 1 : 1,000 to 1 : 60 have been re ported." However, most of

these cases are mild in nature. Acquired vascu lar disease is thought to be a risk

factor for this occurrence.

The vast majority of orbital and periocular hemorrhages are venous in

origin. Usually, they are not vision-threatening and more often require

postponement of surgery than any intervention. Alternatively, arterial he

morrhages can produce proptosis, ecchymosis, and chemosis. In the pres ence o

rapid orbital swelling causing a tight orbit, marked proptosis, oph thalmoplegia,

and blood-staining of periorbital tissues, a retrobulbar hemorrhage of arterial

origin should be suspected. Vision loss occurs as a result of the tamponade

effect of the periorbital swelling wherein the in traorbital pressure rises higher

than does the intraarterial pressure. Also, occlusion of the microvasculature of

the optic nerve can occur, causing a late optic atrophy.

If the diagnosis of retrobulbar hemorrhage is suspected, pressure

measurement and ophthalmoscopy are indicated. Treatment is immedi ate latera

canthotomy-cantholysis and close follow-up of intraocular pres sure (lOP) and

vision. Emergent orbital decompression surgery may be considered if the optic

nerve is compromised.

Permanent impairment of vision in such patients has not been shown to

occur. Direct arterial trauma is the suspected cause, and no modifica tion in

technique has demonstrated avoidance of this complication.

Globe Perforation

Globe perforation is one of the most dreaded complications of local

anesthesia. Several retrospective studies reported isolated cases of globe

perforation. Incidence of globe perforation ranges from 1: 1000 to 1 : 4200 in

reported cases and, in patients with axial lengths greater than 26 mm, the

incidence increases to 1 : 140. 7 In addition, axial myopes also have thinner

sclera, placing them at further risk. Other risk factors for globe perforation

include enophthalmos or nanophthalmos, multiple injections or injection sites,

and a history of a scleral buckling procedure.


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Whether advantages accrue to sharp rather than blunt needles is un known. Use

of blunt needles has been thought to avoid this risk, but cases of blunt-needle

perforation have occurred. Also, performing strictly peribulbar blocks does not

obviate the risk of perforation, although the incidence is lower with the

peribulbar technique.f Because techniques and needle types vary, determining

the relative risk of globe perforation is difficult. The risk of perforation has not

been proven in any controlled study.

Symptoms of ocular penetration include severe pain and sudden loss of

vision, and signs include hypotony, sudden increase in lOP, and sub -conjunctival hemorrhage. When suspected, indirect ophthalmoscopy should be

performed to confirm the diagnosis, but scleral exploration is not necessary, as

the perforation sites often are small and self-sealing. If the media are not clear

enough to allow visualization of the retina, the sur geon may proceed with

cataract surgery. Otherwise, treatment entails immediate cryopexy or episcleral

implant for anterior perforations or laser photocoagulation to posterior

perforations. Systemic antibiotics should be administered to reduce the risk of

endophthalmitis.

Complications of perforation include subretinal, retinal, and vitreous

hemorrhage; retinal holes; or detachment. The degree of postoperative visual

recovery depends on the location of the perforation (although the majority are

below the fovea), presence of a retinal detachment, and development of

proliferative vitreoretinopathy.

Muscle Injury

Although exceedingly rare, another complication oflocal ocular anes thesia

is direct muscle trauma with subsequent diplopia. The cases reported most

commonly are of inferior rectus palsies or contracture after blocks .m d of

superior rectus overaction. Increased use of peribulbar blocks has been

implicated as a cause, given the multiple injections or injection sites used with

this method; however that the use of hyalu ronidase is thought to improve the

efficacy of this technique, thereby re quiring less injection of anesthetic.

The mechanism of muscle injury is speculative. One theory contends that

direct injection of anesthetic into the recti and subsequent myotoxic ity cause

postoperative strabismus. Studies by Rainin and Carlson" sug gested that

surrounding an isolated rectus muscle with high concentra tions and volume of

anesthetic can cause muscle fiber destruction. Trauma to nerves and needle

damage of the rectus muscles also are spec ulated to be causes of postoperative

strabismus.

Another accepted theory is that muscle injury occurs in one of two ways:

Laceration of anterior ciliary vessels causes a hematoma ora large volume of

anesthetic is injected into this same intramuscular or perimus cular space." The

compressive effect of blood or anesthetic is thought to


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Complications of Periocular, sthesla- 89

result in vascular compromise and subsequent muscle fibrosis and con tracture.Overall, muscle paresis after cataract surgery is noted to be temporary,

but cases of permanent muscle injury have been described. These cases of

permanent strabismus are thought to be the result of a myotoxic effect of the local

anesthetic, but the lack of pathological studies in these cases cannot confirm the

etiology.'?

Optic Nerve Injury

Injury to the optic nerve with the anesthetic needle is a great concern in

administering periocular anesthesia. Severe visual deficit on the first

postoperative day may be the clinical presentation.

Direct needle trauma to the optic nerve is not thought to be the mech anism

optic neuropathy after surgery. In fact, optic nerve injury and dysfunction

occurring after local ocular anesthesia is related inherently to retrobulbar

hemorrhage and to central artery occlusion.

Retrobulbar hemorrhage can cause a marked rise in lOP or intraor bi

pressure, thereby causing a central retinal artery occlusion. Intravas cular injectio

of anesthetic also can cause a central vein or artery occlu sion via vasospasm. A

third mechanism for vasoocclusion is the injection of anesthetic into the nerve

sheath, causing a compressive effect first on the venous circulation and later

compromising arterial inflow. Direct needle trauma to the retinal artery in the

posterior orbit, prior to its pen etration of the optic nerve, also is thought to occur.

All these mechanisms cause optic atrophy as a result of vascular compromise.

Needle penetration of the optic nerve rarely causes vision loss but, if

associated with a central retinal artery occlusion, visual dysfunction can be

profound and permanent.

CNS Complications

CNS complications oflocal anesthetic injection can have lethal effects.

In extremely rare instances, after receiving periocular anesthesia, a pa tient m

experience cardiovascular and pulmonary problems, such as hy potension a

respiratory arrest. Drug toxicity can be a cause and may manifest initially as

tremors, agitation, slurred speech, and (eventually) seizure activity. Moreover,

overall nervous system collapse causing respira tory depression an

cardiovascular collapse can occur.

The fisk of nerve trauma or subsequent intrathecal administration of

anesthesia (or both) are thought to be linked. A study of CNS complica tions a

retrobulbar block demonstrated an incidence of 1: 375. Reported rates of CNS

complications range from 0.09% to 1.50%. A life threatening complication ca

occur in 0.13%.11 Effects included apnea


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90 Cyriac and Pineda

and respiratory depression, convulsions, and cardiopulmonary arrest. In -

terestingly, no reported cases occurred in studies wherein a needle length shorter

than 1.5 inch was used. In peribulbar anesthesia, many suggest using needles no

longer than 25 mm.

The clinical picture of CNS anesthesia can be varied. Affected patients may

experience confusion and agitation (which may be normal consider ing

administration of intravenous sedation), dizziness, tremors (ranging from

shivering to marked convulsions), ophthalmoplegia or amaurosis of the fellow

eye, tinnitus or deafness, and problems with speech or breath ing. The onset ofsymptoms usually occurs within a few minutes, peaking at approximately 15

minutes after anesthesia administration. For this rea son, we recommend that the

patient be observed, without drapes, for 15 minutes after administering

anesthesia. The average duration of these symptoms is 2 to 3 hours.

Signs of CNS anesthesia include loss of consciousness, apnea, and limb

paralysis. CNS blockade can manifest as arterial hypertension and tachycardia or

hypotension and bradycardia with cardiac arrest and pul monary edema. These

signs and symptoms can occur in any combination, whereas the earliest findings

are contralateral eye signs and loss of con sciousness. With proper diagnosis and

prompt treatment, full recovery is normal. Treatment is specifically directed

toward seizure control, hemo dynamic support and, in some cases, administration

of cardiopulmonary resuscitation. The nature of this complication of ocular

anesthesia emphasizes the need for careful monitoring of the patient by aqualified anesthesia staff.

The mechanism of this complication is debated. Intravenous or in traarterial

administration has been postulated, but blood levels in patients were not in the

toxic range. Also, doubt has been cast on the intraarterial theory, because no

reports have cited blood in syringes or retrobulbar hemorrhages. Intravascular

injection should produce immediate seizure activity. Grand mal seizure activity

usually is the predominant sign but is not necessarily always present. Respiratory

depression and cardiovascular collapse also should occur injust a few seconds.

This clinical picture after periocular anesthesia has not been reported.

The most widely accepted explanation is direct injection into the nerve

sheath, and it has been shown through orbitography studies using radiocontrast

dye. 12 Anesthetics can gain access to the cranial nerve roots, pons, midbrain, and

spinal cord. Also, the cerebrospinal fluid analysis of patients who developed

respiratory arrest demonstrated lido caine and bupivicaine.P The neurologicalsigns or vision loss from this mechanism are thought to be short-lived, and no

permanent effects have been noted. Direct injection into the subarachnoid space

would cause respiratory arrest within a few minutes, and this is the common

clinical scenario.

Complications of Periocular Anesthesia - 91

Conclusion

No method or technique of local ocular anesthesia is free of compli cation.

We recommend that surgeons perform their preferred technique properly and with

the globe in primary position. The use of blunted, shorter needles 33 mm for

retrobulbar blocks and 20 mm for peribul bar blocks) also is recommended.

Furthermore, the peribulbar technique, although not proved, appears to have an

advantage over the retrobulbar technique in reducing the risk of complications.Many advances in technique have enabled surgeons to achieve excel lent

surgical anesthesia and akinesia. With careful monitoring by qualified individuals

with experience in local ocular anesthesia, the vast majority of cases result in no

serious complication. However, because the administra tion of anesthesia is

essentially a "blind" maneuver, risk of damage to vital neurovascular structures,

orbital tissues, and even to the globe itself is inherent. Therefore, occasional

complications should be expected.

References

12. Unsold R, Stanley .lA, Deg-root J . The CT-topography of retrobulbar anesthesia: anatomic-cinical correlation of complications and suggestion of a modified technique. Graefes Arch

Clin Exp Ophthalmol 1981 ;217:125-136

13. Davis DB, Mandel MR. Posterior peribulbar anesthesia: an alternative to retrobulbar

anesthesia.J Cataract Refract Surg 1986;12:182-184

14. Davis DB, Mandel MR. Efficacy and complication rate of 16,224 consecutive peri bulbar

blocks. J Cataract Refract Surg 1994;20:327-335

15. Katsev DA, Drews RC, Rose BT. An anatomic study of retrobulbar needle path length.

Ophthalmology 1989;96:1221-1224

16. Hay A, Flynn HW, Hoffman .II, Rivera AH. Needle penetration of the globe during

retrobulbar and peri bulbar injections. Ophthalmology 1991 ;98: 1017-1024

17. Edge KR, Martin .I, Nicoli V. Retrobulbar hemorrhage after 12,500 retrobulbar blocks.

Anesth Analg 1994;76:1019-1022

18. Duker JS, BelmontJB, Benson WE, et al. Inadvertent globe perforation during retrobulbar

and peribulbar anesthesia. Ophthalmology 1991;98:519-526

19. Rainin EA, Carlson BM. Postoperative diplopia and ptosis. Arch Ophthalmol 1985; 102:1337

20. Hamed LM. Strabismus presenting after cataract surgery. Ophthalmology 1991;98: 247-25221. Esswein MB, Von Noorclen CK. Paresis of a vertical rectus muscle after cataract extraction.

Am J Ophthalmol 1993; 116:424-430

22. McGoldrick KE. Anesthesia for ophthalmic and otolaryngologic surgery. Philadelphia:

Saunders, 1992

23. Drysdale DB. Experimental subdural retrobulbar injection of anesthetic. Ann Ophthal

1984;16:716-718

24. Kober, KA. Cerebrospinal fluid recovery of lidocaine and hupivicaine following respiratory

arrest subsequent to retrobulbar block. Ophthalmic Surg 19H7;lH:II-13

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Postoperative Complication of Periocular Anesthesia