Case report: Unilateral mydriasis after anesthesia

César Lora*

* Médico anestesiólogo, Universidad Nacional de Colombia; coordinador de Anestesiología, Clínica Hermanos Hospitalarios San Juan de Dios, La Ceja, Antioquia, Colombia

Recibido: octubre 4 de 2009. Enviado para modificaciones: noviembre 10 de 2009. Aceptado: febrero 16 de 2010.

A five year old male boy weighing 13 kg who had dental cavities was scheduled for a complete dental treatment. When the protective tape of the eyes was removed, a fixed right Mydriasis without any light response was observed, without any other changes in the physical examination. On the fourth day, he was assessed by neurology presenting an improvement and the pupillary size. On the fifth day the pupil returned to normal size without any sequela according to family information. A pediatric anesthesia case with unilateral Mydriasis lasting one week after surgery is presented. The differential diagnostic processes are discussed.

Key words: mydriasis, pupil, iris, neurology, ophthalmology, complication (Source: MeSH, NLM)

CASE REPORT

A five year old male boy weighing 13 kg who had dental cavities was scheduled for a complete dental treatment. In the preanesthetic assessment, a history of asthma with a recent crisis three months earlier, that the required no treatment was recorded. He was premedicated per os with three milligrams of midazolam (Figure 1).

As per request of the dentist, a nasotracheal intubation was planned. He had standard monitoring; and an inhaled induction with sevoflurane and 100 % oxygen was used. On the right nostril, 3 to 4 drops of 0,025 % oxymetazoline were applied; then he was anesthetized and a peripheral intravenous line was inserted, through which 15 milligrams of ketamine were administered. A 4,5 tube was easily placed nasotracheally, and afterwards, multiple dental extractions and oral hygiene was performed. He was 300 mg of intravenous dipyrone administered and after an anesthetic duration of 75 minutes, without any record of hypercapnia or oxygenation abnormalities, the tube was removed with the patient awake with prior administration of four puffs of the bronchodilator, ipratropium bromide.

When the protective tape of the eyes was removed, a fixed right mydriasis without any light response was observed, without any other changes in the physical examination. Once fully awake, the neurological evaluation was repeated with persisting right mydriasis with normal and symmetrical globe pressure, and normal fundoscopy.

Two hours later, a CT scan was performed which revealed no abnormality. He was kept in observation for 6 hours and since no ophthalmologist was available on a Saturday afternoon, it was decided to request an ambulatory ophthalmologic consultation 24 hours after the event.

When examined by the ophthalmologist, the mydriasis persisted but it was now reactive to light and had no fundoscopic or ocular pressure changes. The patient was managed ambulatory with medical recommendations by the ophthalmologist. On the fourth day, he was assessed by neurology presenting an improvement and the pupillary size. On the fifth day the pupil returned to normal size without any sequela according to family information.

DEFINITION

Different physiopathologic abnormalities can lead to anisocoria, understanding that the pupillary size depends of the effects on the pupillary autonomic nervous system and the iris muscle (15) (Figure 1).

Areflexic unilateral mydriasis in a patient without any neurological deficit or systemic disease represents an interesting and serious diagnostic problem; the first diagnosis that should be ruled out is the exposition to toxic substances or medications (1). mydriasis secondary to medication is areflexic to light and accommodation and does not respond to instilled 1 % pilocarpine (6, 16).

Thereafter, an iatrogenic cause should be ruled out to avoid unnecessary testing (2,3). In practice, the exposition to mydriatic substances is a common cause of mydriasis. Another less frequent diagnostic possibility is the benign unilateral episodic mydriasis which in its physiopathology encompasses both a parasympathetic deficit as well as a sympathetic hyperactivity on the affected iris (4,9,14).

The finding of a unilateral mydriasis under general anaesthesia is stressful and the neurological evaluation is limited. The possible causes include, exposition to anesthetic medications, stellate cervical ganglia blockade, abnormal head and neck venous return, acute symptoms of intracranial masses or hemorrhage, direct ocular trauma, preexisting surgical or medical conditions, or inadvertent instillation of alpha or anticholinergic agents on the eye (5,10,12). In nasal endoscopic surgery, the nasal mucosa is commonly prepared with decongestants to minimize blood loss and to ease surgical exposition. These commercial preparations commonly contain 5% lidocaine and 0,5 % phenylephrine, and its use can lead to mydriasis (3).

Oxymetazoline is sympathomimetic and is commonly used as a nasal decongestant and it is usually recommended at a dose of 2 to 3 nasal drops every 12 hours, in children between two and five years old. It is considered that its local vasoconstrictor effect can inhibit absorption which minimizes any systemic effect (12).

On the other hand, ipratropium bromide, a common bronchodilator can rarely produce mydriasis in susceptible patients (2,11). Ipratropium bromide is a quaternary anticholinergic agent that produces bronchodilation in asthmatic patients slower than beta 2 inhaled agents, but its effect on these patients is variable, which has been related to the differences in bronchial parasympathetic tone in certain individuals (13).

The use of misnamed "recreational" drugs as ecstasy (3, 4 methylenedioxymethamphetamine), can produce the release of monoamine neurotransmitters (serotonin, dopamine) and enhance the inhibition of the uptake of serotonin which can produce mydriasis and an increase in intraocular pressure in susceptible individuals (7).

DIAGNOSIS

When the patient has an acute variation of his pupillary diameter, an exhaustive and detailed assessment should be performed, as well as an identification of the abnormal pupil, and a differential diagnosis should quickly be made to exclude possible causes (1, 2, 8). With the physical examination findings like the size of the pupil and its reaction to light and darkness can help identify the problem (15).

The size of the abnormal pupil should be measured, under exposition to light and darkness. If anisocoria is greater with light, the problem is in the difficulty for pupillary contraction and is called mydriasis. Among its causes are: compression of the third cranial nerve leading to secondary palsy, Adie´s tonic pupil, pharmacological mydriasis or local iris factors like trauma or acute glaucoma. If anisocoria is greater in darkness and the problem is dilation, the problem is miosis. If there is no variation of the pupillary to light or darkness the anisocoria is considered essential or primary (6, 8).

Diplopia and palpebral ptosis can suggest third cranial nerve palsy. Pain could be related to rupture of an intracranial aneurysm that compresses the third cranial nerve or to carotid dissection. On the other hand, transient intermittent anisocoria is commonly related to benign causes like migraine (14, 15).

The anxiety of the described finding should be controlled and if a traumatic or pharmacological factor is excluded then neurological imaging should be ordered as well as complementary ophthalmological and neurological assessments (1,2,6,8).

DISCUSSION

This case is that of a pediatric patient without any anesthetic history who was asthmatic which could suggest susceptibility and in whom nasal oxymetazoline was used to reduce the risk of bleeding during nasal intubation. He also received ipratropium bromide puffs through the tube and after a 1 hour period of inhaled anesthesia, developed right unilateral areflexic mydriasis without any visual acuity or accomodation abnormality, nor any other physical finding.

Consultation to ophthalmology and neurology was requested because of the unusual presentation and the persistence of the findings for more than 24 hours. These consultants considered drug exposition as the cause of this finding.

On the other hand, the slow recovery of the pupillary response was noteworthy as it took one week and no sequela occurred. The case was presented because of its infrequent occurrence and for the interesting clinical analysis it represents, as this finding could herald a serious condition in an otherwise healthy patient.

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