week 5

Question 1

Is diabetes mellitus a risk factor for stroke?

Answer 1

Numerous studies have identified diabetes mellitus as a significant risk factor for stroke. The actual mechanisms are unclear, however, diabetes mellitus has adverse effects on a number of aspects of the cardiovascular system. These effects include: changes in vascular responsiveness; thickening of the intima of vessels such as the carotid arteries and hypercoagulablity.

Question 2

Is hypertension a risk factor for stroke?

Answer 2

Hypertension is a major risk factor for stroke, both ischaemic and haemorrhagic. The increased pressure directly increases the risk of rupture of weakened vessels. In addition, ongoing damage to the endothelium of vessels promotes the development of atheromatous plaque leading to vascular occlusion by thrombosis or embolism.

Question 3

What is a lacunar infarct and how do they arise?

Answer 3

Lacunar infarcts are small (0.2 to 15 mm in diameter) infarcts caused by occlusion of a single branch
of a large cerebral artery. The infarcts are in non‐cortical regions, typically in the basal ganglia,
thalamus, pons, or (as in this case) the internal capsule. These branches arise at acute angles from
the large arteries of the circle of Willis, stem of the middle cerebral artery (MCA), or the basilar
artery

Question 4

whats syndromes does lacunar infarct give rise to

Answer 4

infarcts give rise to 5 syndromes: pure motor stroke (contralateral
hemiparesis/hemiplegia); ataxic hemiparesis (combination of cerebellar and motor symptoms,
ipsilateral to the lesion); dysarthria/clumsy hand (difficulty in speech and coordination, especially
writing ‐ ipsilateral); sensory stroke, including numbness or tingling/burning sensation usually
contralateral; mixed sensorimotor stroke with sensory effects and hemiparesis or hemiplegia ‐
ipsilateral. The syndromes are observed on the contralateral or ipsilateral side to the stroke
depending on the level of the infarct.

Question 5

Where is the internal capsule and what is its function?

Answer 5

The internal capsule is a conduit of axons passing to and from the cortex and thalamus or spine. It passes between the basal ganglia. The anterior limb carries sensory fibres from the thalamus to the sensory cortex and the posterior limb carry the corticospinal tracts and cortico‐thalamic fibres from the primary motor cortex. In this case the lesion is in the left posterior limb of the internal capsule affecting the corticospinal tract.

Question 6

What is the anatomy of the blood supply of the internal capsule? Which vessels are probably affected?

Answer 6

The internal capsule is supplied by branches of the middle cerebral artery (MCA). In particular, the lenticular striated arteries which are very vulnerable to hypertension‐related haemorrhages and blockages. They are small and so the area of infarct associated with an occlusive event in one of these vessels is small.

Question 7

What is hemiparesis?

Answer 7

Hemiparesis is muscular weakness down an entire side of the body affecting limbs and facial muscles. Hemiplegia is the more severe form with actual paralysis of the distal musculature. Postural muscles are not affected (at least not to as great an extent).

Question 8

Why are mainly distal muscles affected?

Answer 8

The internal capsule carries the corticospinal tracts (aka. Pyramidal tracts), these control fine movement in distal muscles. The extrapyramidal tracts are not as affected by such lesions and so postural control is achievable.

Question 9

What challenges might this patient face in daily life and what role can Occupational Therapy play in his rehabilitation?

Answer 9

Such a patient will have problems with locomotion, manipulation of objects and, possibly actions like drinking. Generally, such a patient would be able to stand, but walking would require modification of gate whereby the affected leg is assisted by rotation of the torso using postural muscles. Occupational therapy would provide the patient with strategies and techniques to develop independence.

Question 10

Risk factors. for a stroke

Answer 10

 Increasing age
 Hypertension – the most important risk factor which can be changed!  Heart disease
 Atherosclerosis
 High blood cholesterol levels
 Hypercoagulability
 Diabetes mellitus
 Smoking
 Oral contraceptives and pregnancy
 Cocaine use

Question 11

whats neurosis

Answer 11

Severe ischaemia → neurones and glial cells die → liquefactive necrosis
 Cells will be broken down by their own enzymes and the tissue replaced with cerebrospinal fluid.