New concepts of cerebellar control of eye movements

Investigating the causes of vertigo in breast cancer survivors

The vertigo symptom in breast cancer survivors has rarely been mentioned. The aim of this study was to investigate the causes of vertigo in breast cancer survivors with vertigo. From May 1997 to April 2003, 36 consecutive female breast cancer survivors with vertigo underwent a battery of tests including physical examination, neurological examination, serum lipid profile, plain chest radiograph, whole body bone scan, liver sonography, audiometry, electronystagmography (ENG) and MRI scan. Based on these tests, the causes of vertigo were attributed to peripheral labyrinthine origin in 14 patients (39%) and central origin in 22 patients (61%) consisting of 11 cases of vascular insufficiency, eight of hyperlipidemia and three of posterior fossa metastases (8%). The latter included one case of cerebellopontine angle and two of cerebellum, accompanied by extracranial systemic metastases, e.g., of the lung, bone or liver. In conclusion, vertigo in breast cancer survivors warrants concern, especially in those with extra-cranial systemic metastasis accompanied by headache. In addition to 8% occurrence of posterior fossa metastasis, other possible causes for vertigo in breast cancer survivors consist of vascular insufficiency, hyperlipidemia and labyrinthine lesion.

The Chiari I malformation and the neurotologist

OBJECTIVE

The first objective of this paper is to report the clinical symptoms of 77 patients and the results of their neurologic, vestibular, and audiological evaluations done with magnetic resonance imaging, which confirmed Chiari I malformations. The second objective is to report how the results of a vestibular evaluation can help neurosurgeons decide on the need for surgical treatment.

STUDY DESIGN

Retrospective chart review of 77 patients seen between 1988 and 2000.

SETTING

Tertiary care center.

PATIENTS

The clinical data of patients under diagnoses of Chiari I malformation, which was filed in the vestibular laboratory computer, was analyzed.

INTERVENTION

The cases included in this study were derived from a population of patients who were evaluated for dizziness, hearing loss, and tinnitus in the Torok Vestibular Laboratory.

MAIN OUTCOME MEASURE

Occurrence of central vestibular findings in the patients with Chiari I malformation.

RESULTS

In this group of 77 patients, 10 had bilateral sensorineural hearing loss and 22 had unilateral sensorineural hearing loss of varying severities. Horizontal spontaneous nystagmus was noted in 27 patients, vertical upbeat nystagmus in 3, and downbeat nystagmus in 4 others. Saccadic dysmetria was noted in 4 patients, optokinetic nystagmus was impaired in 3, and smooth-pursuit impairment was noted in 12 of the group. Positional nystagmus was noted in 9 patients. The Torok monothermal caloric test showed normal responses in 19 patients, hyperactive responses in 43, decruitment in 45, and rebound caloric nystagmus in 20. Surgical decompression of the Chiari I malformation was completed in 33 patients.

CONCLUSION

From this study it is clear that the results of the basic vestibular function-test battery reflect the functional deficit in the vestibulocerebellum that is presumed by its ectopic position. These tests results have given our neurosurgeons a stronger foundation on which to base surgical decisions for this disease.

Smooth pursuit eye movements in schizophrenics--what constitutes quantitative assessment?

Although a voluminous literature exists on the eye movements of schizophrenic and affective disorder patients, many of the assessments made of smooth pursuit have been qualitative in nature. Most of them have not differentiated between abnormal functioning of the smooth pursuit system and intrusion of inappropriate saccades during a smooth tracking task. Specific identification of the pursuit or saccadic defect is necessary if the origins of the abnormalities are to be understood and related to psychopathology. Analytical techniques, such as the ln(S/N) ratio, although numerical in nature, are still unable to discriminate among pursuit and saccadic defects, as shown by our analysis of simulated tracking. Thus, to understand the effects of psychiatric disorders on the ocular motor system, specific defects must be identified and quantified.

ENG-MRI correlates in cerebellar oculomotor dysfunction

This study correlates ENG and MRI findings in six patients with cerebellar eye movements. For each subject, both tests independently support the presence of a cerebellar tract abnormality. In two patients, MRI studies confirmed the site of cerebellar dysfunction previously demonstrated by ENG. Although the number of patients is small, the strong correlation (100%) indicates that ENG remains a sensitive method for detection and localization of the origin of cerebellar eye movements. The physiologic information provided by ENG is supported anatomically by MRI. The cerebellar eye movement abnormalities are briefly reviewed.