| Abstract #892, Date 2/18/99, Session Z, Podium , 9:00a |
| Oscillopsia secondary to gentamicin induced vestibulotoxicity and concurrent head tremor in kidney transplant recipients |
| *M.T. Yen, S.J. Herdman, R.J. Tusa (Bascom Palmer Eye Insitute, Miami, FL) |
Renal failure patients are very susceptible to gentamicin induced vestibulotoxicity. These patients often complain of head-induced oscillopsia whereas patients with nystagmus from central disorders experience constant oscillopsia. Kidney transplantation is becoming a more frequently used treatment for patients with renal failure. Modern immunosuppressants have dramatically improved organ transplant survival; however, these medications may also induce neurotoxic effects including head tremor. Two commonly used immunosuppressants are cyclosporine and tacrolimus. We describe two cases of pseudonystagmus and constant oscillopsia in kidney transplant patients with gentamicin induced vestibulotoxicity and concurrent head tremor from tacrolimus. Methods: Static and dynamic visual acuity with and without head fixation was measured. Vestibular function was evaluated with head-thrust test and ice water calorics. Head tremor was recorded in head-straight and head-turn positioning. Results: Both patients had a noticeable head tremor and pseudonystagmus. In one patient, the head tremor was recorded at 4 Hz, and worsened to 7 Hz with head turn. By reducing their head tremor with head stabilization, both patients showed a one-line improvement in their static visual acuity. When the head was oscillated at 2 Hz (dynamic visual acuity), a 4-line loss of visual acuity in one patient and a 10-line loss in the second patient occurred. One patient underwent vestibular rehabilitation and had improvement of his symptoms. Conclusions: This is the first description of pseudonystagmus and oscillopsia at rest in patients with gentamicin induced vestibular hypofunction and immunosuppressive medication-induced head tremor. Unlike other patients with aminoglycoside induced vestibulotoxicity, these patients experience constant blurred vision and oscillopsia. Cyclosporine and tacrolimus are two commonly used immunosuppressants that are well known to induce head tremor. Patients may improve with reduction of immunosuppressant dosage, other medications to reduce head tremor, or with vestibular rehabilitation. |