Journal of Neurology, Neurosurgery, and Psychiatry 1988;51:509-515 Lacunar syndromes due to brainstem infarct and haemorrhage CY HUANG, E WOO, YL YU, FL CHAN* From the University Department of Medicine and the Department of Diagnostic Radiology,* Queen Mary Hospital, Hong Kong Nine patients with brainstem infarct and two with brainstem haemorrhage presented with pure motor stroke, pure supranuclear facial palsy, sensorimotor stroke or ataxic hemiparesis. Despite the clinical similarity with hemispheric lacunes, brainstem infarcts causing lacunar syndromes probably have a greater tendency to progress. Small brainstem haemorrhages should also be considered as a cause of lacunar syndromes and the difficulty in differentiating them from small infarcts without CT is emphasised. SUMMARY Lacunar syndromes have been described in vascular lesions of the brainstem and hemisphere. Most clinico-radiological studies using computed tomography (CT) have, however, concentrated on hemisphere lesions' 2 with only sporadic reports of brainstem lesions. We described here our experience in 11 cases presenting with lacunar syndromes due to infarct or haemorrhage in the brainstem. Patients and methods Eleven patients were seen with CT evidence of a brainstem vascular lesion and clinical features consistent with pure motor stroke,3 supranuclear facial palsy,4 sensorimotor stroke,5 or ataxic hemiparesis6 (table). Patient 11 with ataxic hemiparesis was reported previously and will not be described here.' Computed tomography (CT) of the brain was obtained using a GE 9800 scanner with contiguous 10mm slices. Four patients presented with pure motor stroke. Three were due to paramedian infarcts in the basis pontis (Patients 1 to 3, figs 1-3), and another had a small tegmental haemorrhage (Patient 4, fig 4). The infarct patients showed progressive deterioration after onset of the symptoms, whilst the haemorrhage patient actually noted improvement of symptoms by the time he arrived at the hospital. A case of pure supranuclear facial palsy due to a paramedian pontine infarct was also seen (Patient 5, fig 5). Four patients (Patients 6 to 9, fig 6 to 9), three having ischaemic and one haemorrhagic lesions, presented with a sensorimotor stroke. The ischaemic lesions were bigger than those of pure motor stroke, and in two cases, separate adjacent lesions were seen. Progression of deficit was noted in two of the ischaemic cases. Two patients had ataxic hemiparesis, with one as the dysarthria-clumsy hand variant (Patients 10 and 11, fig 10). The lacunes in these two patients were situated in the ventrolateral aspect of the brainstem. ILLUSTRATIVE CASES Pure motor stroke Case 4: TPC, a 52 year old Chinese male was admitted with a sudden onset of left hemiparesis associated with transient diplopia, vomiting but no headache. By the time of admission, he was better subjectively. There was a history of heavy Address for reprint requests: Dr C Y Huang, Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong. Received 15 September 1987. Accepted 1 October 1987 Fig I LMN, 67 year oldfemale with pure motor stroke. 509 Huang, Woo, Yu, Chan 510 Table Summary of clinicalfeatures Motor Progression of Patient Sex/Age (yr) Pathology Pure motor stroke 1 LMN F/67 F/61 2 CWK F/42 3 LKL M/52 4 TPC LL UL Sensory Facial Weakness power power Impairment Infarct Infarct + Infarct Haemorrhage - Ataxia Other Symptomsl Neurological deficits Signs 2 4 4 4 2 4 4 4 - - Vomiting, Diplopia + + - Risk factors Hypertension Hypertensior Hypertension Hypertension smoking + - Pure supranuclear facial palsy Infarct 5 Cs M/65 + 5 5 - - Dysarthria - Smoking Sensorimotor stroke 6 CL F/58 F/70 7 LY 8 NCS F/58 + 0 0 0 0 Proprioceptive Nociceptive Nociceptive Proprioceptive Nociceptive (UL only) - Dysarthria + Diabetes Vertigo Headache + Diabetes - Vertigo - Hypertensior - + (UL only) Dysarthria + - Hypertensior Diabetes, Hypertensior 9 LK M/57 Ataxic hemiparesis M/62 10 CYC F/52 11 HC Infarct Infarct Infarct 3 0 Haemorrhage - 3 2 Infarct Infarct 4 3 5 4 + - Motor power in limbs graded according to MRC scale: UL = upper limb, LL = lower limb, + = present, cigarette smoking and of irregularly-treated hypertension for 2 years. On examination he was found to have a mild left hemiparesis of MRC grade 4 in both upper and lower limbs and normal facial symmetry. Tendon reflexes and plantar responses were normal bilaterally, as were the sensorium and the rest of the neurological examination. Blood pressure was 150/90 mmHg. CT showed a small right lateral tegmental pontine haemorrhage (fig 4). There was no progression of signs and he made a complete recovery in 2 months. Pure supranuclear facial palsy Case 5: CS, a 65 year old Chinese male was admitted with an acute onset of slurred speech and drooling of saliva for 3 days. There was no history of vertigo, diplopia, ataxia, nausea, vomiting, limb weakness or sensory impairment. Past health was unremarkable. He smoked 40 cigarettes a day. On examination there was a mild weakness involving the lower half of the right face only. Frontalis and orbicularis oculi activity as well as taste were intact. There was a mild dysarthria present but no uvula or tongue abnor- 1 Fig 2 CWK, 61 year oldfemale with pure motor stroke. absent. 3K, 6 w .:I %-I Fig 3 LKL, 42 year oldfemale with pure motor stroke. Lacunar syndromes due to brainstem infarct and haemorrhage Fig 4 TPC, 52 Year old male with pure motor stroke. t..... :: _ 21'."1. w I_ fM :..~~~~~~~~~somm .. _~~~~~~U" _~~~~~~l _ Af W Fig 5 CS, 65 Year old male with pure supranuclear facial pals!y. 511 512 Huang, Woo, Yu, Chan over 20 years. He had an episode of spontaneous vertigo an hour and not by other symptoms 2 lasting accompanied years previously. He neither smoked cigarettes nor drank alcohol. He developed a sudden left sided weakness in the daytime and on admission was found to be dysarthric, with mild weakness of the right side of the face, and MRC grade 4 power in the right arm which also showed dysdiadochokinesia and ataxia. Tendon reflexes were unremarkable and there was no sensory deficit. Blood pressure was 160/90mmHg on admission and the rest of cardiovascular examination was normal. A hypodense lesion was visualised in the ventrolateral region of the brainstem on the CT scan performed 17 days later (fig 10). He made a good recovery over the next 3 months. Discussion Fig 6 CL,..8 year old femak with sensorimotor str.... Fig 6 CL, 58 year oldfemale with sensorimotor stroke. mality and the gag reflex was normal. The rest of the nervous system was also normal. Blood pressure was 130/80 mmHg, no bruits were heard and the heart was normal. CT performed 10 days after onset showed a small hypodense area just lateral to the middle of the pons on the left (fig 5). The facial weakness resolved completely over the next few weeks. In their original description of pure motor stroke, Fisher and Curry described pontine infarction as the underlying pathology in three cases.3 Subsequently Fisher and Caplan8 added another case. In more recent years, pontine infarction has been visualised on CT in four other cases of pure motor stroke.9 10 In addition pure motor stroke has been seen with infarcts in the cerebral peduncle" and medullary pyramid.'2 -15 As in the previous cases, our three cases of pure motor stroke were found to have an ischaemic lesion in the paramedian aspect of the pons (fig 1 to 3). In addition to the motor weakness, Fisher and Curry's original three cases of pathologically proven brainstem infarct causing pure motor stroke3 Sensorimotor stroke Case 8: NCS, a 58 year old Chinese woman found that she had a mild left hemiparesis upon waking up in the morning. She had a mild headache the night before, but there were no vertigo, diplopia, or other symptoms. She had been told some years ago that she had mild diabetes which did not require drug treatment. On admission there was a MRC grade 3 left hemiparesis, with mild left supranuclear facial weakness and dysarthria, accompanied by decreased touch, pin prick, temperature and position sense on the left. Vibration sense was absent below the knees and distal to the elbows bilaterally. Cardiovascular examination was unremarkable: pulse was 80/min regular, blood pressure was 150/80 mmHg and there was no bruit heard in the heart or neck. After admission, the weakness progressed steadily till she became hemiplegic by the next day. CT performed on day 2 revealed a large right pontine infarct (fig 8). Investigation revealed a blood glucose of 12-9 mmol and diabetes mellitus was confirmed by persistent glycosuria and hyperglycaemia. The sensory deficits gradually abated and at 3 months she was able to walk with a quadripod despite a foot drop. She remained however devoid of left hand function or movements. Ataxic hemiparesis Case 10: CYC, a 62 year old Chinese male was known to be hypertensive and receiving anti-hypertensive treatment for Fig 7 L Y, 70 year old female with sensorimotor stroke. 513 Lacunar syndromes due to brainstem infarct and haemorrhage signs to differentiate whether the lesion is situated in the cerebral peduncle, pons, or medulla. Of the cases studied pathologically, the responsible lesions included lacunes confined to the medullary pyramid and extending rostrocaudally for only 3 mm in one case and being 2 x 1 x 4mm3 in another,"4 and two lesions of 8 mm diameter in the basis pontis and extending for 7mm and 14mm respectively. Fisher and Caplan8 reported another case, with a pontine infarct of 10 x 10 x 6 mm. Two other reports did not specify the actual lesion size. " 12 Apart from technical difficulties, the small size of the lesions may explain why brainstem infarcts are much less often visualised in CT. Huang and Broe4 described cases of pure supranuclear facial palsy associated with lacunes in the internal capsule and corona radiata, while Puvanendran et al'6 had earlier postulated that brainstem corticobulbar tract involvement could probably give rise to the same syndrome, and drew attention to with stroke. sensorimotor Fig 8 NCS, 58 year oldfemale Dejerine's original description of pontomedullary fibre bundles which leave the pyramidal tracts to showed additional difficulty in gaze associated with supply the facial nucleus. Kuypers"7 described the horizontal nystagmus on looking away from the corticobulbar tracts in humans and also pointed out hemiplegic side in one and dysphagia in two. Stiller et that the supranuclear fibres to the facial nucleus al'0 reported a patient who experienced episodes of depart from the pyramidal tract only close to the transient diplopia and non-specific dizziness during nucleus in the caudal part of the pons and approach the week before admission. A sensation of dizziness the nucleus medially. In case 5 of the present series, without vestibular signs was noted in two other CT revealed a small lacune almost in the middle of the patients.9 In the present series transient diplopia was lower pons, a site consistent with the previous anatnoted in the case with pontine haemorrhage (Patient omical studies (fig 5). Until recently there has been uncertainty as to 4). Thus, gaze paresis away from the hemiplegia, dysphagia, and a history of diplopia would indicate a whether sensorimotor stroke could be considered a brainstem localisation for the pure motor stroke. lacunar syndrome. We have shown that sensorimotor However, there appear to be no consistent clinical stroke due to a hemisphere lacune is best diagnosed ;: :-: k: e: ... -:.e-: --: ::-n- :-s -- - .o. . enoi-:otor 57 y w..it a oldmale Fig -' :LK:: Fig 9 LK, 57 year old male with sensorimotor stroke. 514 Fig 10 CYC, 52 year old male with dysarthria-clumsy hand syndrome. only in those patients with incomplete motor or impairment.' Using this more stringent definition, capsular lacunes can be differentiated from brainstem and large hemispheric lesions presenting as sensorimotor stroke. It is interesting to note that whilst all the cases of pontine infarction causing pure motor stroke on CT had been due to a single lesion, two of the sensorimotor stroke cases showed instead two separate hypodense areas (figs 6, 7). This may suggest that the paramedian artery territory includes mainly the corticospinal tract while the medial lemniscus fibres receive good collateral supply from the circumferential branches so that sensory involvement is only present when more than one branch vessel is involved. If this is the case, brainstem sensorimotor stroke is more likely to be due to a nonlacunar infarction with more sinister basilar artery trunk involvement and the clinical course of such cases is more likely to be progressive. In this regard, it is worth noting that progression was noted in all three cases of pure motor stroke (cases 1 to 3) and in two cases of sensorimotor stroke (cases 6, 8). Progressive deterioration was also noted in six of the eight previously reported cases of brainstem ischaemia causing pure motor stroke.389 In comparison, Rascol et al reported progression in 15 of 28 of the cases of non-brainstem pure motor stroke. We have similarly noted deterioration in only seven of 42 cases of ischaemic pure motor stroke who did not have demonstrable brainstem lesion (unpublished data). It is possible therefore that brainstem pure motor stroke is also more prone to progressive deterioration, sensory Huang, Woo, Yu, Chan perhaps related to the pathology being situated in the basilar artery rather than in a smaller vessel. This may have implication as to more aggressive forms of therapy. The natural history of other brainstem lacunar syndromes awaits further documentation. Brainstem infarction7 18 19 and haemorrhage20 - 23 have also been seen as the underlying vascular lesion in ataxic hemiparesis and its variant, dysarthriaclumsy hand syndrome. Huang and Lui6 pointed out that a pontine location for ataxic hemiparesis could be suspected when there were accompanying nystagmus and cranial nerve involvement but no sensory impairment. Somatosensory evoked potential studies have been normal in two of the previous cases.7 19 On CT, the ischaemic lesions were all seen in the ventrolateral aspect of the pons. The lesions of each of these reported cases of pontine infarction have been limited in the rostrocaudal direction to less than 10mm. The consistent site of the lesions would support the concept that corticopontine and corticospinal projections are interrupted as a result of occlusion of a lateral penetrator branch arising from the short circumferential branches of the basilar artery. Brainstem pathology producing pure sensory stroke has only been reported in one case, a case of midbrain haemorrhage.24 The patient complained of numbness and tingling in the arm and leg but did not have any abnormality on sensory testing. The haemorrhage was seen in the dorsolateral midbrain at the site of the medial lemniscus and spinothalamic tract. The small size of any lesion causing pure sensory stroke is probably the reason why ischaemic lesions have not been visualised so far with CT in the brainstem. Hopefully magnetic resonance imaging will be able to detect such cases in future. Lipohyalinolysis is the major vascular pathology in capsular lacunes. Whether the same applies to brainstem lacunes as has been suggested25 is far from conclusive. In the few cases with pathological findings, lipohyalinolysis was not the prominent feature. Fisher and Curry3 described two cases of pure motor stroke and brainstem infarct associated with basilar artery atherosclerosis. Fisher and Caplan8 found occlusion by atheromatous plaque of a branch of the basilar artery in another case of pure motor stroke. In Ho's case,9 the basilar artery was patent but atherosclerotic. No vascular occlusion was found and the presence of hyalinised vessels close to the infarct suggested probable thrombosis of a small penetrating artery. Ropper's case of medullary lacune was associated with an obliterated penetrating artery and severe atherosclerotic disease of the vertebral and basilar artery. 4 The case of medullary pyramidal infarction described by Chokroverty et al had atheromatous plaques scattered throughout the major Lacunar syndromes due to brainstem infarct and haemorrhage cerebral arteries,"2 whilst the case studied by Ho and Meyer had patent vertebral arteries and basilar arteries with narrowing of the lumen by patchy areas of calcified atheromatous changes.'5 Thus, basilar artery atherosclerosis appears to accompany brainstem infarcts frequently even when they present clinically as lacunar syndromes. Indeed, there is at present no pathological correlation for the CT visualised infarcts. Whether they are really lacunes or much larger lesions due to occlusion of more than one vessel remains to be answered. Prior to the availability of CT the prognosis of brainstem haemorrhage had been held to be dismal. Since the advent of CT more benign cases have been described.26 27 A lateral tegmental brainstem haemorrhage syndrome has been recognised featuring ipsilateral conjugate gaze palsy, ipsilateral internuclear ophthalmoplegia, a small reactive pupil, ipsilateral ataxia and contralateral sensorimotor impairment.26 The present cases (Patients 4 and 9) and the others in the literature underline the even more benign presentation of brainstem haemorrhage, presenting as pure motor stroke,28 pure sensory stroke,24 sensorimotor stroke,23 or ataxic hemiparesis.20-23 It is noteworthy that there were no useful symptoms or signs in our two cases or those in the literature which would allow confident separation of these small haemorrhages from ischaemic brainstem lesions presenting as lacunar syndromes. The dorsolateral location of most of these haemorrhages would suggest that they are due. to rupture of the circumferential branches rather than the paramedian arteries. 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