Systemic disease: Vascular disorders with neurological consequence

Many neurological disorders have underlying vascular complications as the cause. Here are three cases from practice which, though rare, might present in primary care practice

Many neurological disorders have underlying vascular complications as the cause. Here are three cases from practice which, though rare, might present in primary care practice.

Case 1 – Vertebral artery rupture and cerebellar stroke

In July 2009 patient CW, aged 63, a very fit man who ran marathons decided to go for a long run. Prior to the run he did some vigorous shoulder exercises and felt dizzy and experienced vertigo-like symptoms. He decided to lie down and went to sleep. On awakening he could not move his right arm and he could not stand up at all. He also found he lost his balance and was falling towards the right side. Losing his mobility, he became bed-ridden for a couple of days.

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A week later he was able to get out of bed and found there was a small but gradual improvement. He was also booked to see a neurologist privately who undertook an MRI scan and this confirmed vertebral artery dissection. Since there was no obvious bleed he was prescribed warfarin for a stroke due to infarct.

The patient also found that he could not hold a pen and it took a month before he could hold one and many more weeks later before he was able to write with it. Luckily, three months later he had recovered sufficiently and the warfarin was continued for another three months and then stopped.

Optometric examination

6/12 R -1.00DS VA 6/6 Add +2.50DS N5

6/12 L -0.75DS VA 6/6 Add +2.50DS N5

Anterior segment was normal and pupil reactions were normal with direct, consensual and near reflexes. There was no diplopia and no tropia, no motility defect and no saccadic defect. Fundus examination revealed no fundus abnormality. Visual field examination revealed no visual pathway defect.

MRI and carotid MRA scans

MRI scan (Figure 1) shows a definite acute infarct of the right cerebellum

MRA scan (Figure 2) shows a definite dissection of the right vertebral artery

There was no obvious effect on the pons, brain stem or the mid brain.

The diagnosis from the MRI and MRA scan was right vertebral artery dissection and an acute right cerebellum infarct. The likely cause was the vigorous shoulder exercise would have caused the vertebral artery to tear/rupture within the neck.

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Case 2 – Carotid artery rupture and partial Horner’s syndrome

Male mechanic SB, aged 63, had been suffering from thumping headaches on the left side for a few days. He was also experiencing ‘heat’ and numbness on the left side. By the time he saw me he had developed a mild ptosis on the left side, together with a smaller pupil on the left side compared to the right. He had been taking anti-anxiety drug pregabalin and this was being slowly reduced to 75mg and he thought all these symptoms were associated with the slow withdrawal of the drug.

Ocular examination (Figure 3)

With monovision contact lenses he was achieving 6/6 in the right eye and N5 in the left eye

External examination revealed grade 1-2 ptosis of the left upper eyelid

External examination revealed miotic left pupil measuring 3mm compared to a dilated 6mm right pupil

Pupil reactions appeared normal to direct, consensual and near reflexes

The patient experienced mild numbing and heat sensation on the left side

There was no diplopia and no motility or saccadic defect

Fundus examination was normal.

He was referred through his general practitioner urgently to a neurologist for a possible partial Horner’s syndrome.

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MRI and MRA scans

The neurologist undertook an MRI scan and this confirmed a left carotid artery dissection leading to Horner’s syndrome. He also undertook a chest X-ray and this eliminated a lung carcinoma (Pancoast’s tumour). There was no treatment instigated and it was suggested to reassess in three months’ time. The headaches had eased and his appointment was rescheduled for another month later. By the time he re-attended the clinic the consultant had left the NHS and the patient saw a junior doctor to be told ‘all was well’. The patient wanted a copy of his scan but this was not forthcoming. Fortunately, courtesy of a radiologist, we have an angiogram of a dissected left internal carotid artery together with a thrombus which would lead to a stroke. Also attached are our 2011 images of the recovered Horner’s syndrome (Figure 4).

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Vertebral and carotid artery dissection

Vertebral and carotid artery dissections are relatively rare although in patients younger than 45 years they are the main culprits accounting for 20 per cent of ischaemic strokes. The incidence of arterial dissection is estimated to be 2.75 per 100,000. Carotid artery dissection is four times more common than vertebral artery dissection and there is thought to be 3:1 female to male ratio. The reason for carotid artery dissection being more common is that it is a more exposed artery whereas the vertebral artery is shielded by the vertebrae.

Pathology

The pathology of both these dissections is similar. The tear begins either in the innermost layer (tunica intima) or in the middle layer (tunica media) of the vessel. Lifting of the inner layer from the wall of the artery results in luminal stenosis (narrowing, see Figure 3). A blind pouch is created due to the lifted layer leading to localised collection of blood outside the lumen of the blood vessel, an intramural haematoma, predisposing the patient to a thrombus (Figure 3). Dissection occasionally can also occur between the medial wall (tunica media) and the outer wall (tunica adventitia) resulting in an aneurysmal outpouching of the arterial wall which can lead to distal embolisation.

For the vertebral artery, the portion between cervical C1 and C2 is the most common site for vertebral artery dissection. Figure 5 shows the tortuous path and the pinching that the vertebral arteries experience at the site marked by red arrows C1 and C2. The vertebral arteries are shown in green.

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Causes

Causes of arterial dissection can result from neck manipulation (chiropractic) or from neck strain during sports activity, yoga or something as simple as turning the head to reverse, coughing or overhead painting. Penetrating or blunt trauma and seat belt injury during a crash are also causative factors. Respiratory tract infection and hypertension can also cause artery dissection. Underlying connective tissue disorders, such as Ehlers-Danlos syndrome, Marfan’s syndrome as well as fibromuscular dysplasia, predispose a patient to arteriopathy and therefore account for most of the pathology.

Presentation

Patients may present with constant, throbbing headaches, neck and face pain with both the carotid artery and vertebral artery dissection. Vertebral artery dissection can affect the pons and lead to cranial nerve palsies and ophthalmoplegia while effects on the cerebellum will be described later on.

Carotid artery dissection can cause focal weakness, affect taste and, if the blood flow to the retina is affected, symptoms of transient visual loss are experienced by the patient. Fifty per cent of patients with carotid artery dissection experience unilateral oculosympathetic palsy, a partial Horner’s syndrome.

Partial Horner’s syndrome

Partial Horner’s syndrome leads to mild ptosis due to loss of sympathetic innervation of the Muller’s muscle and miosis due to loss of sympathetic innervation to the dilator muscle on the ipsilateral side. It is termed partial Horner’s syndrome in view of the fact that the patient does not experience anhydrosis (lack of sweating) on the affected side. This is due to the fact that the external carotid artery innervates the facial sweat glands rather than the internal carotid artery. Full Horner’s syndrome occurs when the common carotid is affected, ie before it bifurcates into the external and internal carotid artery.

Treatment

The majority of arterial dissections resolve spontaneously and healing can take up to 3-6 months, although dissection of the opposite artery is higher in affected individuals so regular follow-up is important. Those who experience cerebral ischaemia require anti-thrombotic treatment with warfarin or heparin. In those showing no improvement with anticoagulants, surgery to the affected vessel with either a stent or angioplasty is undertaken.

Cerebellum stroke

Cerebellar strokes are very rare, seen in 1 per 200,000 annually. Cerebellar infarction is an important cause of stroke with patients presenting with symptoms of dizziness, nausea, unsteady gait, ataxia, diplopia and headaches. Lesions of the superior cerebellar artery, anterior inferior cerebellar artery or the posterior inferior cerebellar artery will result in cerebellar stroke syndrome. The posterior inferior cerebellar artery (PICA) is the largest cranial branch of the vertebral artery and its branching occurs way before the two vertebral arteries meet and become a single basilar artery. Laterally it extends into the cerebellar vallecula and divides into medial and lateral branches. The medial branch supplies the cerebellar hemispheres, as seen in our patient’s case. Early diagnosis is crucial to prevent fatal complications such as brainstem compression (due to high intracranial pressure) and obstructive hydrocephalus (abnormal accumulation of cerebrospinal fluid in the ventricles). The anatomy of the cerebellum is important in understanding the symptoms patients experience with an infarct.

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Anatomy of the cerebellum

The cerebellum is located at the base of the brain, with a large mass of cerebral cortex above it and the pons in front of it (Figure 6). All of its connections to the brain travel through the pons and, although it does not initiate movement, it contributes to coordination, precision and accurate timing of motor activity. Because of this fine tuning function, damage to the cerebellum does not cause muscle paralysis but rather poor coordination of activities such as writing, playing the piano or running.

The function of the cerebellum is fine motor movement, balance and equilibrium and muscle tone. Cerebellar stroke would lead to disorders in fine movement, equilibrium, posture and motor learning and all of this depends on the part of the cerebellum that is affected. Damage to the vestibular part (flocculonodular lobe) may cause loss of equilibrium and in particular a wide stance due to difficulties in balancing – walking gait. Damage to the lateral zone (cerebrocerebellum) results in problems with skilled voluntary and planned movements, the disruption of fine movement of hands or limbs.

Damage to the midline portion (vermis) may disrupt whole body movements. Damage to the lower part is more likely to cause uncoordinated or poorly aimed movements of arms and hands, as well as difficulties in speed. These complex motor symptoms are referred to as ataxia.

Identification

To identify cerebellar problems, assessment of gait, posture and finger pointing test are important.