Abstract

Aphonia induced by conversion disorder during surgery is a rare event. We report a woman 28 years of age who was undergoing a Cesarean section under epidural anesthesia. The patient sustained aphonia without detected neurologic deficits. Emergency consultations of a psychiatrist and neurologist were carried out in the operating room postoperatively. After a thorough medical and neurologic work-up, the consultative psychiatrist and the neurologist unanimously made the diagnosis of conversion disorder. Thirty-six hours after the operation, the patient's voice started to return. We venture on sharing the findings of this case with our fellow anesthesiologists in order to highlight discussion and illuminate the differential diagnosis. We have reviewed the literature and excluded an organic lesion as the culprit of the event.

Keywords

anesthesia, epidural; aphonia; conversion disorder;

1. Introduction

The annually reported incidence of conversion disorder ranges from 11 per 100,000 to 300 per 100,000 in the general population.¹ The term “conversion” was first introduced by Sigmund Freud, who conceptualized that the abnormal functioning deportment rose from defense mechanism by which unconscious conflicts which manifest as deficit or repressed thought was expressed symbolically or somatically. It was previously known as hysteria, hysterical neurosis, conversion hysteria, or conversion reaction. The diagnosis should be made only after appropriate investigations that exclude neurologic conditions, medical conditions, and other psychological disorders. Patients of conversion disorder are usually studied in a psychiatric setting. Here we report a young, physically healthy woman who experienced conversion disorder that manifested aphonia during a Cesarean section under epidural anesthesia.

2. Case report

A woman 28 years of age (gravida 2, para 1) was scheduled to undergo Cesarean section for the delivery of her second baby. She weighed 60 kg and stood 166 cm. Her previous Cesarean section with epidural anesthesia proceeded uneventfully. She had no history of psychiatric illness, special medical disease, or drug abuse. Her vital signs were normal and the physical examination did not reveal any significant findings. The preoperative electrocardiography and laboratory data, which included complete blood count (hemoglobin, hematocrit, white blood cell count, platelet count), liver function (glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, bilirubin), kidney function (blood urine nitrogen, creatinine), and coagulation profile (prothrombin time, partial thromboplastin time), were unremarkable. As it is the common practice in our hospital, epidural anesthesia is mostly used for this operation. Premedication was omitted.

Upon arrival in the operating room, an electrocardiograph (ECG) monitor was applied. Oxygen (4 L/minute) was administered by facemask. Baseline blood pressure (109/74 mmHg), pulse rate (73 beats/minute), and pulse oximetry (99%) were measured and recorded. Noninvasive blood pressure was automatically measured and recorded every 3 minutes. Lactated Ringer's solution (500 mL) was infused intravenously rapidly during induction of anesthesia. An epidural catheter (19 gauge) was introduced into the epidural space through an 18-gauge Tuohy needle at the L3-4 interspace in the left lateral decubitus position. The epidural space was identified by loss of resistance to air injection, into which 5 cm of catheter was inserted. After a negative aspiration, a testing dose of 3 mL of 2% lidocaine viscous was injected through the catheter anchored in the epidural space. After no paralysis of lower extremities and no cardiovascular alteration were induced in 10 minutes, a 20 mL bolus of 2% lidocaine viscous with epinephrine 1:200,000 was injected accordingly. Boluses of 5 and 15 mg ephedrine were given intravenously to treat hypotension (systolic blood pressure <80 mmHg) respectively at 5 and 10 minutes after the anesthetic injection. Blood pressure returned to the pre-anesthetic level within 2–3 minutes in each episode. The analgesia was delimited at T6 level to pinprick stimulation. The patient did not complain of breathlessness and no signs of respiratory distress were visible. The baby was delivered 30 minutes after commencement of anesthesia with normal appearance and acceptable Apgar score. During the operation, the patient seemed to be fully anxious. She attentively listened to what the obstetrician spoke. After the baby being subjected to childbirth care (1 hour of anesthetic injection), the patient heard that her baby should be transferred to the newborn center for further observation (a routine settlement for the newborn in our hospital). It was likely that the patient misinterpreted the wording, representing something wrong with her baby. She became extremely anxious and irritable. We pacified her by reassuring remarks that it was a routine practice for newborns to be observed and watched for a period in the newborn center and it did not indicate the need of urgent medical management. She seemed to show resolution of the anxiety and breathed freely. However, we began to notice that she had difficulty in speaking. She remained conscious and displayed a remarkable calmness. She seemed to understand what we were saying to her. She tried to answer but could not utter a word. She could move her mouth, lips, tongue, head, and upper extremities upon command. Her lower extremities were paralytic due to the unfading regional anesthesia. Her lungs were clear and her heart sounds remained normal on auscultation. Her pulse oximetry read 99% of oxygen saturation. Arterial blood gas analysis showed PaO₂ of 150 mmHg, PaCO₂ of 37 mmHg, pH of 7.38, and blood sugar of 73 mg/dL. Complete blood count, electrolyte levels, and the thyroid function were normal. Blood pressure and heart rate were stable (105∼120/60∼70 mmHg and 80∼95 beats/minute) throughout the incidence. We were able to communicate with the patient by her nods in response to our questions. She responded to a painful pinprick stimulation elicited above the level of T8. Our first concern about the incident was a possible cardiovascular attack. Emergency consultations with the hospital psychiatrist and neurologist were carried out in the operation room. On physical examination, gagging reflex was elicited by touching the posterior wall of the pharynx with a wooden tongue depressor. She could not utter a cry of “ah” in response to the oral manipulation but had no difficulty in swallowing saliva. She displayed no weakness in turning the head rightward and leftward against resistance. No lateral deviation and weakness in protruding of the tongue were visible. Her pupils were equal in size and reactive to light. Although increasing muscle tone of her upper extremities was found, the pattern of which was not consistent with that of a neuropathic lesion. Both our psychiatrist and neurologist suggested that the patient should go through more extensive studies before any definite diagnosis could be made. Therefore, electroencephalography (EEG) and magnetic resonance imaging (MRI) were arranged immediately at the conclusion of surgery. However, EEG showed no epileptiform activities. No definite organic lesion was found in the MRI of brain and spine. The consulting psychiatrist and neurologist ultimately made the diagnosis of conversion disorder. The patient was administered 10 mg of diazepam intravenously and transferred to the intensive care unity for further observation. Ninety minutes after the operation, the patient was able to bend her knee and flex her thigh after the fade of the regional anesthesia. Thirty-six hours later, the patient was able to talk again. Her baseline physical status was restored completely. She was discharged without sequelae on postpartum Day 6.

3. Discussion

Aphonia during epidural anesthesia is probably caused by direct neural blockade to generalized toxicity of the central nervous system.2, 3 Our patient was tenacious of her vitality with unmolested spontaneous breathing, intact movement of both arms, and unchanged facial expressions. She did not develop tonic-clonic movements or an altered state of consciousness. The incidence of aphonia could not be explained by the outcome of accidental total spinal blockade or inadvertent intravenous injection of local anesthetics. An amniotic fluid emboli and transient hypotension from regional blockade could likely compromise cerebral or vertebrobasilar circulation.⁴ The patient could control her facial movements, move her lips, tongue, and eyes with intact visual field. She did not manifest quadriplegia and hemiplegia. Therefore, cerebral or brainstem ischemia was excluded.

Most reports of conversion disorder were often associated with general anesthesia.5, 6, 7, 8, 9, 10, 11 Paralysis and failure to restore consciousness are the common presentations of the victims. Cases of aphonia or conversion disorder developing in regional anesthesia are illustrated in Table 1. Some of these patients suffering from aphonia were due to high spinal block.12, 13 Conversion disorder related to epidural anesthesia as culprit was rarely reported. Drexler et al.¹⁴ reported a case of transient aphonia and quadriplegia during epidural anesthesia. This patient recovered within 25 minutes after the injection of 10 mL of 0.5% bupivacaine. It was concluded that this was a transient ischemic attack caused by hypotension during the anesthetic procedure. Parker et al.¹⁵ disagreed with this statement based on neural anatomy, and believed that the incident was due to hysterical conversion. Chhibber et al.¹⁶ reported a case in which motor loss and hyperesthesia to touch, vibration, pressure, and temperature of the left leg occurred some 11 hours after the recovery from the spinal block. MRI of the spine revealed no abnormality. Even though the patient had no psychological or psychiatric disorder diagnosed previously, the psychiatric consultant finally made the diagnosis of conversion reaction. Laraki et al.¹⁷ reported a case of hysterical paraplegia and aphonia after epidural anesthesia. Mack et al.¹⁸ disagreed with the determination since it was considered only after other possible diagnoses were dismissed and the sensory level was not right-and-left, which was not consistent with a psychological etiology. However, the sensory loss in both legs of the patient was patchy and without a clear upper level. Anal tone was normal and reflexes in the affected limbs were preserved. All the evaluations including a computed tomography scan and MRI were reported to be normal. Full recovery of sensation and strength took place on postoperative Day 6. The diagnosis was likely to be conversion disorder. Kumar et al.¹⁹ reported a woman 30 years of age who developed aphonia after having undergone the ultrasound-guide supraclavicular brachial plexus blockade (20 mL of 0.375% bupivacaine with 1:200,000 epinephrine) for excision of a swelling in the right forearm. Haile et al.²⁰ reported a woman 58 years of age who underwent left shoulder arthroscopy under general anesthesia. The surgeon implanted a catheter into the shoulder joint for postoperative rehabilitation. She also developed aphonia after administration of the local anesthetic (20 mL of 0.5% bupivacaine with 1:200,000 epinephrine). In these two patients, acute aphonia presented as an isolated sign. Since the resolution of aphonia occurred within the expected duration (6 and 7 hours, respectively) of the bupivacaine block, diffusion of the local anesthetic to the laryngeal nerve was their conviction of the underlying mechanism that caused laryngeal nerve paralysis. We are dumfounded by their statement because patients with laryngeal nerve paralysis should present hoarseness, dyspnea, stridor, and swallowing disability, instead of aphonia.

Table 1. Cases of aphonia or conversion disorder developing in regional anesthesia.

Download full-size image

Differential diagnoses for psychogenic aphonia include somatization disorder, hypochondriasis, conversion disorder, malingering, and factitious disorder. Both somatization disorder and hypochondriasis are chronic illnesses and have numerous medically unexplained physical symptoms.²¹ This was inconsistent with our patient's sudden onset of aphonia. In malingering and factitious disorder, the symptoms are under conscious and voluntary control. By contrast, there was no evidence that our patient intentionally pretended to make the symptom (e.g., acquiring opiate injection, insurance indemnification) under unmolested consciousness.

The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, defines conversion disorder as a symptom or deficit of voluntary motor or sensory function that cannot be explained by a known neurologic or medical disorder.²¹ Psychological factors are required to initiate and exacerbate the neurologic symptoms. Typically, the symptom is of sudden onset. Unlike somatization disorder, patients with conversion disorder focus upon one symptom. Conversion disorder risk factors often include being female, with little education, and of low socioeconomic status.⁷ Patients of conversion disorder are usually young, between 10 and 35 years of age, with characteristics of immaturity, dependency, histrionic behavior, sexualization of relationships, and have low frustration tolerance.7, 11 Depression, anxiety, and interpersonal conflicts may accompany or exacerbate the symptoms of conversion disorder.22, 23, 24, 25 Our 28-year-old patient was a housewife with a high school education. During her visit to our psychiatrist, she mentioned that she was having financial difficulties and experiencing family conflict. Therefore, it was quite possible that she developed aphonia secondary to her anxiety over financial difficulties and her baby's health. She apparently showed a lack of concern (La belle indifference) regarding the loss of her voicing function (aphonia) since such a physical symptom was so effective in relieving her mental anguish.

Conversion symptoms are generally of short duration (about 2 weeks at most) and recur in about 20%–25% of patients within 1 year. If the symptoms are temporary, and could be resolved by suggestion, hypnosis, parenteral amobarbital, or lorazepam, then they are probably suggestive of conversion disorder. Although conversion symptoms will remit on their own in some cases, psychological management techniques are needed to bring about a resolution of symptoms in many patients.¹ Some patients will be refractory to psychological therapy; others will develop a recurrent pattern of conversion symptoms in response to stress, injury, or illness.²⁶

This was an uncommon case of conversion disorder with sudden onset during a Cesarean section with epidural anesthesia. An extensive work-up and consultation of specialists were indispensable to confirm the diagnosis. Conversion disorder is always suspected when the symptoms are not anatomically or physiologically consistent with the patterns of organic diseases. Treatment and management of conversion disorder during the perioperative period with regional anesthesia should center on immediately removing the underlying stress from patient, reassurance of absence of life-threatening illness or anesthetic complications, careful statement of the diagnosis, and referral to a specialist at the conclusion of surgery. However, a psychiatric disorder may be accompanied by medical conditions. Obtaining a thorough medical history and performing a thorough physical examination are essential in all cases.