Br J Ophthalmol: first published as 10.1136/bjo.72.7.515 on 1 July 1988. Downloaded from British Journal of Ophthalmology, 1988, 72, 515-517

The one-and-a-half syndrome. Clinical correlation with a pontine lesion demonstrated by nuclear magnetic resonance imaging in a case of

C N MARTYN AND D KEAN From the University Departments of Medicine and Radiology, Royal Infirmary, Edinburgh

SUMMARY Nuclear magnetic resonance (NMR) imaging has been used to visualise a localised area of demyelination in the dorsal of a patient who presented with an unusual disorder of eye movements, namely, the one-and-a-half syndrome. Judged clinically the patient made a nearly complete recovery, but little change was apparent in the NMR image six months later.

The unusual and remarkable disorder of eye move- eye movements in response to head turning. A ment consisting of a lateral gaze palsy in one direction contralateral internuclear ophthalmoplegia was and an internuclear ophthalmoplegia in the other was present: the left eye failed to adduct past the midline, probably first described by Freeman et al. and later and horizontal jerking was apparent in the dubbed the one-and-a-half syndrome by Fisher.2 In abducting right eye. Up-gaze was incomplete with the fully developed syndrome one eye is in the gaze-evoked upbeat nystagmus, and convergence midline and completely fails to move horizontally was impaired. Figs. 1-3 illustrate the horizontal gaze while the other can only abduct. Fisher attributed the palsies. There was an incomplete left-sided facial syndrome to a single unilateral lesion affecting the palsy of lower motor neurone type, and taste http://bjo.bmj.com/ centre for conjugate lateral gaze in the paramedian sensation was lost on the left side of the tongue. pontine reticular formation and the adjacent ipsi- Abdominal reflexes were absent, and both plantar lateral medial longitudinal bundle. This anatomical responses were equivocally extensor. localisation has been confirmed at necropsy in several Eight years earlier she had been investigated cases. Recorded causes of the syndrome include extensively but inconclusively for an episode of tumour, trauma, infarction, haemorrhage, and bilateral foot drop associated with paraesthesiae

demyelination.34 We report a further case, occurring on September 25, 2021 by guest. Protected copyright. in a patient with multiple sclerosis, in which the lesion was successfully visualized during life by magnetic resonance imaging. Case report A 30-year-old woman presented with a two-week history of , unsteadiness of gait, and altered taste sensation. She had noticed, too, that her face had become asymmetrical. Examination revealed a complete horizontal gaze palsy to the left for volun- tary and tracking eye movements and also for reflex

Correspondence to Dr C N Martyn, MRC Environmental Epidemiology Unit, University of Southampton, Southampton Fig. 1 Patient is attempting to look straight ahead. No General Hospital, Southampton S09 4XY. abnormality ofconjugate gaze is apparent. 515 Br J Ophthalmol: first published as 10.1136/bjo.72.7.515 on 1 July 1988. Downloaded from

516 C N Martyn and D Kean

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Fig. 2 Patient attempts to look right. The right eye abducts, Fig. 3 Patient attempts to look left. There is no movement of but the left remains fixed at the midline. either eye. affecting both lower limbs. Myelography had been positive at 1:1000, VDRL and TPHA tests for normal and no abnormalities in the cerebrospinal syphilis negative on both blood and CSF, serum B12 fluid (CSF) had been detected. She had recovered and folate normal. CSF protein was 282 mg/l and fully within three months. Four years later she had oligoclonal bands were not detected. The CSF cell experienced paraesthesiae and weakness affecting count was 1/mm3. The CT scan was normal, and the whole of her left arm in association with difficulty there were no abnormalities on chest x-ray. Visually in manipulating small objects with her left hand. No evoked responses to a reversing checker board investigations had been undertaken, but she again stimulus demonstrated a delay of the P100 wave in made a full recovery within a few months. While this the right eye of 18 ms relative to the left. report was being prepared she sustained a typical Nuclear magnetic resonance imaging was per- attack of left-sided retrobulbar neuritis. formed on a low field (0-08T) resistive MR system56 Investigations during her most recent illness were with a TR (repetition rate) of 1 second and a TI (time as-follows: erythrocyte sedimentation rate 11 mm/h, from inversion) of 200 ms. Lesions such as those antinuclear factor test negative, DNA binding <5 found in demyelinating conditions produce an eleva- units/ml (normal less than 25 units/ml), Mantoux test tion in magnetic relaxation times and were clearly

shown by NMR.5 Figs. 4 and 5 are T, weighted images http://bjo.bmj.com/ which show a left-sided abnormality in the lower on September 25, 2021 by guest. Protected copyright.

Fig. 4 A sagittal T1 weighted image showing highsignal Fig. 5 A transverse T1 weighted imageshowingthatthe from the area ofpontine demyelination. lesion is confined to the leftside ofthe dorsalpons. Br J Ophthalmol: first published as 10.1136/bjo.72.7.515 on 1 July 1988. Downloaded from

The one-and-a-halfsyndrome in a case ofmultiple sclerosis 517 pontine tegmentum. This area of prolonged T. is ing. This case shows the value of magnetic resonance typical of an area of demyelination. imaging techniques in the investigation of brain stem The patient was treated with dexamethasone 8 lesions. Not only has it been possible to localise the mg/day for five days. Her facial palsy, loss of taste, lesion producing this unusual combination of dis- and internuclear ophthalmoplegia recovered gradu- orders of eye movements within the pons but infor- ally over the next month. After six months her only mation about the pathology of the lesion has been remaining abnormality was vertical nystagmus on up- provided. NMR allowed a definite diagnosis to be gaze. She was re-examined by NMR, which, despite reached during the acute phase of the illness without the clinical improvement, showed little change. recourse to invasive investigations. Discussion We are grateful to Dr M A Smith, Miss R A B Douglas, and Mrs A Blane, of the NMR Imaging Unit, Royal Infirmary, Edinburgh, for This woman has sustained four episodes of neuro- their help with this case. logical disturbance in the past nine years, recovering completely or nearly completely from each. There References has never been any clinical or laboratory evidence of an arteritic condition or of sarcoidosis. Although 1 Freeman W, Ammerman HH, Stanley H. Syndrome of the there are no typical abnormalities in the CSF, the pontile tegmentum: Foville's syndrome: report of three cases. Arch Neurol Psychiatry 1943; 50: 462-71. diagnosis is almost certainly multiple sclerosis. 2 Fisher CM. Some neuro-ophthalmological observations. J Neurol The one-and-a-half syndrome is thought to be Neurosurg Psychiatry 1967; 30: 383-92. caused by a lesion in the lower pontine tegmentum 3 Pierrot-Deseilligny C, Chain F, Serdaru M, Gray F, Lhermitte F. affecting the sixth nerve nucleus and the lateral gaze The one-and-a-half syndrome. Electro-oculographic analysis of five cases with deductions about the physiological mechanisms of centre in the adjacent paramedian reticular forma- lateral gaze. Brain 1981; 104: 665-99. tion as well as the ipsilateral median longitudinal 4 Wall M, Wray SH. The one-and-a-half syndrome-a unilateral fasciculus. In this case the facial weakness and disorder of the pontine tegmentum: a study of 20 cases and review disturbance of taste indicate that the seventh nerve of the literature. Neurology 1983; 33: 971-80. 5 Smith MA, Best JJK, Douglas RHB, Kean DM. The installation nucleus and the rostral part of the nucleus of the of a commercial resistive NMR imager. Br J Radiol 1984; 57: tractus solitarius, or alternatively the infranuclear 1145-58. fibres of the facial nerve and nervus intermedius as 6 Kean DM, Smith MA, Douglas RHB, Best JJK. Description of a they pass through the pons, were also affected. A low field resistive MRI system and its application in imaging small lesion affecting exactly this area is clearly midline central nervous system pathology. Clin Radiol in press. demonstrated by nuclear magnetic resonance imag- Acceptedforpublication 18 May 1987. http://bjo.bmj.com/ on September 25, 2021 by guest. Protected copyright.