Does hearing loss after spinal anesthesia differ between young and elderly patients?

Abstract

Fifty male patients scheduled for inguinal hernia repair with spinal anesthesia were included in this study. The patients were divided into two groups: 25 patients aged 30 yr or younger (Group Y) and 25 patients aged 60 yr or older (Group E). We performed subarachnoidal injection at the L3-4 interspace by using a 25-gauge Quincke needle with the patient in the sitting position, and 3 mL of 0.5% isobaric bupivacaine was administered. Patients were evaluated by pure tone audiometry (LdB [low frequencies], 125-500 Hz; SdB [speech frequencies], 500-2000 Hz; HdB [high frequencies], 2000-6000 Hz) on the day before and 2 days after spinal anesthesia. Low-frequency hearing loss observed in Group Y was significantly more common than in Group E (P < 0.01). There was no difference between the groups in speech and high frequencies. Mild hearing loss, defined as a hearing loss of 10-20 dB at two or more frequencies, was observed three times more frequently in Group Y than Group E (52% vs 16%; P = 0.014). We conclude that transient hearing loss was more common in young patients after spinal anesthesia, perhaps because the cerebrospinal fluid leakage after dural puncture is less in the elderly than in the young, a finding also associated with the infrequent incidence of postdural puncture headache in the elderly. Spinal anesthesia is one of the most frequently used regional anesthesia techniques in surgical interventions; however, rarely it may cause some transient or permanent neurological problems. One of these problems is headache, which is more frequent and severe in the young, and hearing loss, especially at low frequencies. Both the pain and the hearing loss are caused by leak of cerebrospinal fluid caused by the puncture in the membrane of the spinal cord during the procedure. We hypothesized that hearing loss might also be more frequent and severe in the young, and to test this hypothesis, we compared the hearing loss developing after spinal anesthesia between the young and the elderly. The implications of this study are as follows: First, spinal anesthesia must be performed carefully, especially in the young. Second, measures must be taken to avoid the leak of cerebrospinal fluid. This study reveals possible problems caused by spinal anesthesia in the young which can be easily overlooked.