Ocular manifestations of hindbrain-related syringomyelia and outcome following craniovertebral decompression

Purpose To analyse and evaluate associated ocular symptoms and signs in hin dbrain-related syringomyelia and their response to treatment. Methods From a database of 275 patients treated in a single institution for hindbrain hernia and syringomyelia, 39 patients (14%) had ocular symptoms and signs. Only 31 patients were included in this study; the remainder were excluded due to inadequate follow-up information. All patients had confirm ed evidence of hindbrain-related syringomyelia with MRI scan or CT myelogra m. Treatment included craniovertebral decompression or ventriculoperitoneal shunting. The mean follow-up was 23 months. Results In addition to the well-recognised sign of downbeat nystagmus, clas sically associated with foramen magnum abnormalities, a number of other oph thalmic features were identified. Symptoms included diplopia, oscillopsia, tunnel vision and difficulty in lateral gaze. Signs included nystagmus (dow nbeat, horizontal, rotatory, and combinations), strabismus, disc pallor, an isocoria, ptosis and field defect. Patients were categorised into two group s depending on whether the ocular features were manifest at first presentat ion (group 1, n = 14) or developed later in the course of the disease (grou p 2, n = 17). The delay in diagnosis from first presentation was 5 and 6 ye ars respectively. All patients underwent surgery. Craniovertebral decompression was performed in 13 patients in group 1 and i n 15 patients in group 2. Ventriculo-peritoneal shunt was inserted in 1 pat ient in group 1 and in 3 patients in group 2, for the associated hydrocepha lus. Following surgery, 100% of patients in group 1 and 82% of patients in group 2 had complete or partial resolution of their ocular symptoms and sig ns. Conclusions The presence of unexplained ophthalmic features such as nystagm us or oscillopsia should alert one to the potential diagnosis of hindbrain- related syringomyelia. Delay in diagnosis is often associated with poorer o utcome. Surgical treatment can offer excellent results for these patients.