Eight-and-a-half syndrome: a rare presentation

Abstract

Eight-and-a-half syndrome is a rare entity characterised by conjugate horizontal gaze palsy, ipsilateral internuclear ophthalmoplegia and ipsilateral lower motor neuron type facial palsy. It is due to a lesion affecting median longitudinal fasciculus, paramedian pontine reticular formation and facial nerve fascicle on the same side at the level of pons. The diagnosis is easily missed as it needs detailed ocular movement examination. It is mainly caused due to infarction or demyelinating conditions. We are reporting an interesting case of a 54-year-old man with right-side eight-and-a-half syndrome due to acute ischaemic stroke and ST-elevation myocardial infarction of the inferior wall.

Background

Brainstem strokes are difficult to localise but extremely fascinating. Eight-and-a-half syndrome is a rare neurological condition characterised by loss of ipsilateral horizontal conjugate eye movement, internuclear ophthalmoplegia and lower motor neuron type facial palsy.¹ It is due to a lesion affecting median longitudinal fasciculus (MLF), paramedian pontine reticular formation (PPRF) and facial nerve fascicle on the same side at the level of pons.² The PPRF is located at the level of pons. It is the centre for horizontal conjugate gaze. At the same time, MLF facilitates the yoked eye movement. Eight-and-a-half syndrome is difficult to diagnose if not suspected. Detailed ocular movement examination is of paramount importance. The common causes include stroke and demyelinating conditions but can also be seen in cases of space occupying lesions of brain.¹

The co-occurrence of acute myocardial infarction (AMI) and acute ischaemic stroke (AIS) is a serious condition.³ It has been seen that many patients with AIS have AMI.³ A study has shown that among patients admitted with AIS, 12.7% developed AMI within 72 hours of admission.⁴ However, the co-occurrence of myocardial infarction and cerebrovascular accident is a rare situation. This has been termed as cardiocerebral infarction and was introduced by Omar et al.⁵ Its prevalence is not known as it is a rare situation. The presence of both these life-threatening conditions together makes it difficult in terms of management. We are reporting a case of a 54-year-old man with AMI with AIS of right cerebellum and dorsal aspect of the right half of pons leading to eight-and-a-half syndrome.

Case presentation

A 54-year-old man without any prior comorbidity presented with the sudden-onset retrosternal chest pain, squeezing type, radiating to the neck and not relieving on rest for 2 days. He also started having sudden-onset double vision at the same time. Both the complaints began simultaneously. He had visited a hospital on the day of development of symptoms where thrombolysis with streptokinase was done, and he had improvement in chest pain. He was referred to our hospital for double vision. On examination, he had a pulse rate of 88/min regular in rhythm, normal volume and character, with all peripheral pulses being palpable equally. His blood pressure was 98/66 mm Hg in the right-hand supine position. He was afebrile and had a respiratory rate of 18/min. On CNS examination, he was conscious and oriented. His eye movements were restricted. In the primary position, there was slight esotropia of right eye. The vertical movements of right eye were intact, but horizontal movements were absent. In the left eye, vertical movements, as well as abduction, was intact. Abduction of the left eye was associated with nystagmus with a fast component to the right. Adduction was absent in the left eye (video 1). Pupillary reflex to light was present in both eyes. Convergence was spared and oculovestibular reflexes were absent. This was suggestive of one-and-a-half syndrome of the right side. A possibility of right abducens nucleus involvement was suspected, which was not certain clinically due to entire right sided horizontal gaze palsy. He had a right-sided loss of nasolabial fold, and forehead furrows were lost along with the inability to close the right eye. He also had a deviation of angle of mouth to the left (figure 1). These features were suggestive of right-sided LMN type facial nerve palsy. Other cranial nerves examinations were within normal limits. The Plantar reflex was extensor on the left side and flexor on the right side. He had an abnormal broad-based gait. There were no other cerebellar signs, and sensory examination was within the normal limit. A diagnosis of AMI of the inferior wall with right-side eight-and-a-half syndrome was made.

Video 1.

bcr-2021-244338supp001.mp4 ^{(668.9KB, mp4)}

DOI: 10.1136/bcr-2021-244338.video01

Figure 1.

Eight-and-a-half syndrome. (A) Right horizontal gaze palsy. (B) Absent right eye adduction on left gaze. (C) Right-sided loss of forehead furrows (D) inability to close right eye (E) deviation of angle of mouth to left.

Investigations

His first ECG was suggestive of ST elevation in the lead II, III and aVF. After thrombolysis, there was settlement of ST elevations and the thrombolysis was successful. His renal function tests, liver function tests were normal. He had a normal coagulation profile as well. His HDL was 27 mg/dL and rest all parameters in lipid profile were within normal limits. A two-dimensional echocardiography was suggestive hypokinetic basal inferior and posterior wall with left ventricular ejection fraction 45%–50%. An MRI of the brain and MR angiography was performed, suggesting a subacute infarct in the posterior aspect of the right cerebellar hemisphere and the posterior aspect of the right half of pons. V4 part of the right vertebral artery showed features suggestive of thrombosis (figure 2).

Figure 2.

MRI brain showing subacute pontine and cerebellar infarction. (A) T1-weighted MRI showing subacute infarct in the posterior aspect of the right half of pons. (B) T1-weighted MRI showing subacute infarct in the posterior aspect of right cerebellar hemisphere. (C) T2-weighted MRI showing subacute infarct in the posterior aspect of the right half of pons. (D) Diffusion-weighted image showing subacute infarct in the posterior aspect of the right cerebellar hemisphere and the posterior aspect of the right half of pons.

Differential diagnosis

A diagnosis of ST elevation myocardial infarction with eight-and-a-half syndrome was made from the history and clinical examination. MRI of the brain with MR angiography was suggestive of subacute Infarction in the right cerebellum and posterior aspect of the right half of pons, along with thrombosis of the V4 part of the right vertebral artery. A final diagnosis of Acute ST-elevation myocardial infarction of the inferior wall with ASI of right cerebellum and dorsal aspect of the right half of pons leading to eight-and-a-half syndrome was made.

Treatment

The patient was started on dual antiplatelet therapy, antianginal medications and low-molecular-weight heparin. There was an improvement in the patient’s chest pain. He was started on physiotherapy for facial nerve palsy. Eye care was done with patches and lubricating eye-drops.

Outcome and follow-up

The patient was followed up after 2 months. His chest pain was controlled. He was continued on antiplatelets and antianginal medications and physiotherapy.

Discussion

The term ‘eight-and-a-half’ was coined by Eggenberger, paraphrasing the name given by Miller Fisher to ‘one-and-a-half’ syndrome.⁶ PPRF is the centre for ipsilateral conjugate horizontal gaze. The MLF crosses to the opposite side, and it facilitates yoked eye movement.⁷ A lesion affecting ipsilateral PPRF and the MLF results in ipsilateral horizontal gaze palsy, and internuclear ophthalmoplegia, known as one-and-a-half syndrome.¹

When there is a lesion of ipsilateral PPRF, MLF and facial nerve fascicles resulting in one-and-a-half syndrome with lower motor neuron type facial nerve palsy, this constellation of signs is termed eight-and-a-half syndrome.⁸ It can be easily missed if not suspected. The facial nerve arises from the dorsal surface of the nucleus and travel dorsomedially encircling the abducens nucleus. This leads to a close relationship between the intra pontine fascicles of facial nerve and abducens nucleus leading to risk of involvement of abducens nucleus as well in cases with facial nerve lesion.¹

The common causes of this syndrome are cerebrovascular accidents involving dorsal pons and demyelinating diseases like multiple sclerosis.² It can also be due to space occupying lesions of brain like tuberculomas, tumour, cavernoma and telangiectasias, which are potentially lethal and needs to be diagnosed early for appropriate treatment.^{9 10} In cases of demyelinating conditions, steroid therapy has shown promising effect in some patients.¹¹ For patients with cerebrovascular accident, the management is to be as per stroke guidelines which includes antiplatelets for ischaemic stroke, along with treatment of risk factors like diabetes, hypertension and dyslipidaemia. Eye care with lubricating eye-drops and patching to prevent corneal damage is advisable.^{12 13}

Concomitant AMI and AIS is again a rare and life-threatening condition. There is no appropriate management protocol for the cardiocerebral infarction.³ This is so because there is a difference in the guidelines for the management of ASI and AMI in terms of drugs and their doses. Our patient was thrombolysed with streptokinase for AMI at the first hospital he visited when he was in window period and it was successful. The guidelines by American Heart Association/American Stroke Association have recommended to start intravenous alteplase at a dose appropriate for cerebral ischaemia, followed by percutaneous coronary angioplasty with a level C evidence.¹⁴ The affordability of alteplase is an issue for many patients. Both AIS and AMI have high mortality risk and delay of treatment can be fatal. A more detailed study in this area is still awaited.

This case has been reported to bring into notice that brainstem cerebrovascular accidents are overly complicated but can be accurately localised if examined thoroughly. Also, explicit knowledge on ocular examination is vital in neurological examination and localisation of the lesion. Although most eight-and-a-half syndrome are due to cerebrovascular accident or demyelinating conditions, other lethal causes like tumour, cavernomas, tuberculomas and telangiectasias have also been reported which can be life-threatening if not managed early. The diagnosis of this kind of syndromes can be easily missed if the ocular examination is not done thoroughly. Second, co-occurrence of AIS and AMI is a rare but life-threatening condition that needs to be looked at in-depth to develop a proper management protocol.

Learning points.

• Eight-and-a-half syndrome is a rare condition seen in clinical practice.

• Ocular movement examination is crucial in neurological examination to localise the brain stem lesion accurately.

• Co-occurrence of acute myocardial infarction and acute ischaemic stroke is a life-threatening condition and requires careful and individualised treatment.

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