Stage-assessment of the progress of continuous vertigo of peripheral origin by means of spontaneous and head-shaking nystagmus findings.

The stages of continuous vertigo of peripheral origin were classified into nine categories according to the findings of spontaneous nystagmus (SPN) and head-shaking nystagmus (HSN). The patients analysed were 18 with vestibular neuronitis, 6 with sudden deafness and 6 with unilateral inner ear disorders. 1) Irritative SPN (Stage I) was rarely encountered. 2) SPN of the paralytic type (Stage II) was usually observed in the period less than one month after the onset of diseases. 3) HSN directed toward the intact side with or without a reversal phase (Stages III-2 and III-1, respectively) were the common types of central compensation. 4) The progress of recovery to complete cure (Stage V) was usually rapid once it had actually begun. 5) During the process of recovery, HSN could disappear transitorily (Stage III-3), or be directed toward the affected side without a reversal phase (Stage III-5). Spontaneous recovery nystagmus (Stage IV) could also occur. 6) About 40% of patients recovered to Stage V within about 4 months after the onset of vertigo, but about 30% of patients remained in Stage III-1 or III-2 even after 4 months.