J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.41.12.1084 on 1 December 1978. Downloaded from Journal ofNeurology, Neurosurgery, and Psychiatry, 1978, 41, 1084-1091 Reflex vertical gaze and the medial longitudinal fasciculus L. R. JENKYN, G. MARGOLIS, AND A. G. REEVES From the David Prosser Neurology Research Laboratory, Division of Neurology, Department of Medicine, Dartmouth-Hitchcock Medical Center, and the Department of Pathology, Dartmouth Medical School, Hanover, New Hampshire, USA S U M MARRY Extraocular movements were investigated in a patient with bilateral vascular lesions of the medial longitudinal fasciculus. The patient showed voluntary and reflex horizontal gaze consistent with his lesion, but had absent reflex vertical gaze. Voluntary vertical gaze was present. Necropsy was performed, and the findings suggest that the medial longitudinal fasciculi in the pons convey impulses for reflex vertical gaze, but are not required for voluntary vertical gaze. by guest. Protected copyright. Lesions of the medial longitudinal fasciculus Keane, 1975). A mechanism for the eye move- (MLF) produce characteristic neuro-ophthalmo- ments seen in internuclear ophthalmoplegia has logical findings. Bilateral lesions are most common been postulated by Pola and Robinson (1976), and in demyelinating processes but are also observed recently confirmed by electro-oculographic analysis with occlusive vascular disease and neoplasm of 25 patients (Kirkham and Katsarkas, 1977). (Smith and Cogan, 1959; Christoff et al., 1960; Unilateral hot or cold caloric stimulation of the Cogan, 1970; Gonyea, 1974). With complete semicircular canals results in reflex conjugate bilateral involvement, there is paralysis of adduc- horizontal gaze (Bender, 1959; Shanzer and tion of both eyes with nystagmus in the abducting Bender, 1959). The reflex response, also known as eye. Vertical nystagmus is usually present on the slow component of nystagmus, is thought to upgaze, and convergence may or may not be pre- originate in the hair cells of the horizontal semi- served. Skew deviation is rarely observed (Smith circular canals and to follow a path to the contra- and Cogan, 1959). In less complete lesions, there lateral paramedian pontine reticular formation via may be only paresis of adduction with nystagmus the vestibular nuclei of the side stimulated. This of both eyes in the direction of gaze (Christoff area of the reticular formation is thought to be et al., 1960). Unilateral lesions are caused more the source of integration of both voluntary and commonly by occlusive vascular disease than by reflex conjugate horizontal eye movements demyelinating processes (Cogan et al., 1950; Fine (Bender and Shanzer, 1964; Cohen, 1971; Sharpe and MacGlashan, 1956; Harrington et al., 1966; et al., 1974). With the subject in the supine posi- DeMyer, 1966). tion, unilateral cold stimulation results in reflex Kupfer and Cogan, 1966; Ross and http://jnnp.bmj.com/ The paresis or paralysis of adduction is seen gaze toward the side irrigated, while warm stimula- ipsilateral to the side of the lesion. Abduction tion directs gaze to the opposite side. The cerebral nystagmus is usually present contralateral to the hemispheres are thought to generate a checking or and vertical nystagmus occurs frequently. Con- fast component in the direction opposite to the vergence is preserved. Skew deviation is common slow component that determines the direction of with the elevated eye usually on the side of the the specified nystagmus-that is, nystagmus to the lesion (Smith and Cogan, 1959; Cogan, 1970; left means fast component to the left (Bender, of the lesion. Vertical gaze is usually intact, 1955; Pasik et al., 1960). While some authors cite side on September 24, 2021 the usefulness of double simultaneous caloric This study was supported in part by the Hitchcock Foundation. irrigation in eliciting reflex vertical gaze, we have Address for reprint requests: Dr Lawrence R. Jenkyn, David Prosser found few reports investigating the neural connec- Neurology Research Laboratory, Division of Neurology, Department tions of this mechanism in man (Bender, 1959, of Medicine, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire 03755, USA. 1960; Shanzer and Bender, 1959; Shanzer, 1964; Accepted 27 June 1978 Shanzer et al., 1964). 1084 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.41.12.1084 on 1 December 1978. Downloaded from Reflex vertical gaze and the medial longitudinal fasciculus 1085 In primates, including man, voluntary vertical tion in the carotid arteries. Cerebrospinal fluid gaze is thought to be mediated in the pretectal study revealed protein of 1.12 g/l and glucose of region of the midbrain (Bender and Shanzer, 1960; 8.2 mmol/l with all other parameters within Christoff et al., 1962; Shanzer et al., 1964). Volun- normal limits. EEG and brain scan were normal. tary upgaze is thought to require an intact pre- tectum and posterior commissure (Bender, 1959; NEURO-OPHTHALMOLOGICAL FINDINGS (Fig. 1) Christoff et al., 1962; Pasik et al., 1969a, b), while At rest a skew deviation was present with the left intact structures dorsomedial to the red nuclei are eye 3 mm above the right. Attempts to converge considered necessary for voluntary downgaze after instruction without fixating on a visual target (Bender, 1959; Christoff et al., 1962; Jacobs et al., yielded no eye movements. With tracking of a 1973; Cogan, 1974; Halmagyi et al., 1978). Recent visual target, 2 mm of adduction of the right eye studies in monkeys have confirmed that bilateral and 1 mm of adduction of the left eye were seen. lesions of the MLF eliminate reflex vertical eye An incomplete bilateral MLF syndrome was movements and impair fixation in extremes of present. On voluntary gaze to the right, the right vertical gaze while not affecting voluntary vertical eye abducted 7 mm with nystagmus to the right, saccades (King et al., 1976; Evinger et al., 1977). while the left eye came to the midline without We report a case of bilateral MLF involvement nystagmus. On left lateral gaze, the left eye and impaired reflex vertical gaze with preserved abducted 7 mm with nystagmus to the left, while voluntary vertical gaze which suggest that the the right eye adducted 2 mm past the midline pathway mediating reflex vertical gaze in man includes the medial longitudinal fasciculi. by guest. Protected copyright. 3rr- 2rnm mm Case report (~ <g> < <D \bluntary non-target Tracking A 63 year old white man was transferred on 30 AT REST CONVERGENCE October 1974 to the White River Junction 7mm 62rn4t2mm Veterans Administration Hospital with the chief complaint of increasing lethargy and confusion To right Up over four days. He had a longstanding history of 2mm m diabetes mellitus and severe peripheral vascular To left 7mm Down 5mm disease. Abnormal general findings included a VOLUNTARY GAZE soft mid-systolic murmur and a fourth heart sound. The left leg had no pulses, and the right 7mm '*2mm 7mm leg had been amputated above the knee for ,> <W)' C4f 4m9 : occlusive vascular disease. On neurological ex- Presented left to right Presented upwards Presented right to left amination the patient was arousable and oriented. OPTOKINETIC STIMULATION He had a Cheyne-Stokes pattern of respiration while sleeping. He had no visual field defect, equal 7mm pupils with normal direct and consensual light Head rotated right to left Head extended reflexes bilaterally, normal direct and consensual 7mm 2mm 2mm corneal reflexes bilaterally, decreased gag reflexes Head rotated left to right Head flexed bilaterally, and dysarthria with slight deviation of http://jnnp.bmj.com/ the tongue to the left. Eye movement abnormalities OCULOCEPHALIC STIMULATION are described below. He was able to move all '2D~ extremities to command. Paratonia (resistance to 7mm 4mm movements in all directions) was present diffusely, Right: ice water irrigation Bilaterol ice water irrigation and there was a slight drift with pronation of his ~2mm 7mm right upper extremity. Biceps and triceps reflexes <:ED <D~ do were normal bilaterally. Knee and ankle jerks Left: ice water irrigation Biloteral worm water irrigation were absent in the left leg, and the left plantar CALORIC STIMULATION on September 24, 2021 response was flexor. Sucking, forced biting, and Fig. 1 Schematic presentation of neuro- rooting reflexes were present. Abnormal laboratory ophthalmological findings. A large arrow indicates the values were blood glucose of 19.4 mmol/l and direction of active checking. A small arrow indicates blood urea nitrogen of 10 mmol/l. An old septal the direction of minimal intermittent checking. myocardial infarct was detected on electro- Absence of arrow indicates no checking. No cardiography. Skull radiography showed calcifica- measurement indicates no change from midposition. J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.41.12.1084 on 1 December 1978. Downloaded from 1086 L. R. Jenkyn, G. Margolis, and A. G. Reeves without nystagmus. Vertical tracking of an object dilatation. There was pulmonary congestion and resulted in 2 mm upgaze bilaterally with discon- oedema. Atherosclerosis was severe in the aorta jugate nystagmus upwards, and in 7 mm downgaze and moderate in the coronary arteries. The in the right eye and 5 mm downgaze in the left cerebral circulation exhibited mild atherosclerosis eye without nystagmus. without significant narrowing. Optokinetic responses were elicited by use of an The brain showed a 2 mm cystic infarct in the optokinetic drum while the patient was alert. right cerebral peduncle at the junction of the Optokinetic nystagmus was seen in the right eye, medial and lateral portions. The peduncle medial greater on movement of the stimulus from left to to this zone was palpably softened. In the rostral right than on right to left. In the left eye, there pons, a vertically oriented zone of softening in- was full abduction with the stimulus moving to volved the tegmentum on the left side from the ven- the patient's left and absent adduction with it tricular surface to the pars basalis.