Lacunar Infarct (Lacunar Stroke)

Lacunar Infarct (LACI) is a kind of stroke that affects the brain of an individual. Know all about this condition, its various symptoms and how it is treated.

Lacunar Infarct Definition

It is a form of stroke which occurs due to the blockage of a penetrating artery that controls the blood supply to the deep structures of the brain. An individual is said to have Lacunar Stroke Syndrome or LACS if he or she is experiencing its symptoms but has not undergone the diagnostic imaging procedures. Lacunar Infarcts involving the thalamus are known as Thalamic Lacunar Infarcts while those affecting the pons are called Pontine Lacunar Infarcts.

The condition is also known as Lacunar Stroke.

Lacunar Infarct Epidemiology

These strokes are believed to responsible for around 25% of the total cases of ischemic strokes. Fifteen out every 100,000 people are affected by this condition every year. Men are more prone to it compared to women. People of Mexican, Hong Kong Chinese and African descent have greater risk of developing this condition.

Lacunar Infarct History

Most of the existing information about Lacunar Stroke has been derived from the cadaver dissections of several post-mortem stroke patients by renowned neurologist Charles Miller Fisher. Many “lacunes” (‘empty space’ in Latin) were observed by him in the deep structures of the brain after the occlusion of 200 to 800 micrometer penetrating arteries which connected them with five classic syndromes. These syndromes studied by C.M. Fisher are still observed at present; although, the diagnosis of this condition depends on the radiologic imaging and clinical judgment of the physician.

Lacunar Infarct Classification

The condition is divided into the following types depending on their frequency. All these types are referred to as classical Lacunar Syndromes.

• Pure Motor Stroke or Hemiparesis
• Ataxic Hemiparesis
• Dysarthria or Clumsy Hand
• Pure Sensory Stroke
• Mixed Sensorimotor Stroke

Lacunar Infarct Causes

Occlusion or blockage of one deep penetrating artery arising directly from the components of Circle of Willis basilar artery and cerebellar arteries causes Lacunar Infarct. This results in lesions in the brain’s deep nuclei (10% caudate, 14% thalamus and 37% putamen) and the internal capsule’s posterior limb (10%) or the pons (16%).

Carotid artery pathology from the heart, like in Atrial Fibrillation, can also lead to LACS.

Lacunar Infarct Pathophysiology

The two proposed mechanisms responsible for LACS are known as microatheroma and lipohyalinosis. Initially, Lipohyalinosis was believed to be the principal small vessel pathology. Currently however, microatheroma is considered to be the mechanism which most frequently leads to arterial occlusion (stenosis). In some cases, when the parent artery develops an atheroma it blocks the opening of penetrating artery. This condition is called luminal atheroma. Sometimes, atheroma can also develop at the point of origin of the penetrating artery (junctional atheroma). The mechanism of hypoperfusion is occasionally believed to cause stenosis of penetrating artery as well. If the histologic examination does not show any evidence of the small vessel disease, the cause of the condition is believed to be associated with cardio-embolism or artery-to-artery embolism. A recent study shows that 25% of the total patients, in whom various radiological tests show defined lacunes, had developed the stroke due to potential cardiac causes.

Lacunar Infarcts commonly affect the basal ganglia and lenticular nucleus. Left Thalamic Lacunar Infarcts are very common in patients with this condition. In some rare cases, the infarctions occur in the deep cerebral white matter, the cerebellum and the anterior limb of the internal capsule. However, the cerebral surface, visual radiations and corpus callosum are not generally affected by the condition.

Lacunar Infarct Risk Factors

The risk factors of this condition include:

• Advanced age
• Smoking
• Diabetes mellitus and
• Chronic hypertension

The association of this disorder with factors like elevated cholesterol, alcohol consumption and a history of stroke have not yet been explained in any way.

Lacunar Infarct Symptoms

The disorder is characterized by some common symptoms, including:

• Dizziness
• Loss of vision
• Loss of hearing
• Vertigo
• Balance problems
• Headache

The five different classical Lacunar Syndromes are characterized by different symptoms.

Symptoms of Pure Motor Stroke or Hemiparesis

This form is characterized by Hemiplegia or Hemiparesis that usually affects the arm, leg and face of one side. This results in difficulty in walking, speaking and using the hands. It may also cause Dysphagia and various transient sensory symptoms.

Symptoms of Ataxic Hemiparesis

It is marked by several motor and cerebellar symptoms such as clumsiness and weakness on the affected side of the patient’s body. The legs are more likely to get affected by this disorder compared to the arms. The onset of the symptoms often occurs over several hours or days.

Symptoms of Clumsy Hand or Dysarthria

Dysarthria, clumsiness and weakness of the affected hand are the most common symptoms of this form. These symptoms are often most prominent at the time of writing.

Symptoms of Pure Sensory Stroke

In this form of Lacunar Infarct, the patient experiences transient or persistent numbness, pain, tingling and burning sensations on one side of his or her body.

Symptoms of Mixed Sensorimotor Stroke

Its symptoms include Hemiplegia or Hemiparesis along with an ipsilateral sensory impairment.

Silent Lacunar Infarction

Silent Lacunar Infarction (SLI) is a kind of silent stroke that does not generally cause any noticeable symptoms. People with this type of stroke are usually completely unaware that they have the condition. These strokes are often referred to as old Lacunar Infarction as they generally go unnoticed in the early stages. The SLI strokes usually lead to lesions in various brain tissues. These lesions can be detected through different neuroimaging techniques including CAT (Computerized Axial Tomography) scan and MRI.

The brain tissues in the surrounding area suffer great damage due to the SLIs. Although they do not cause any visible symptoms, SLIs affect the personality, mood and cognitive functioning of the patients. Individuals suffering from an SLI are at greater risk of developing a major stroke in future.

Lacunar Infarct Diagnosis

A doctor studies the detailed medical record of the patient to see if he or she has a history of heart disease, high blood pressure, smoking, diabetes and high cholesterol. The vital signs of the patient, including pulse, breathing rate, temperature and blood pressure, are also checked. The doctor may order an EKG or electrocardiogram for confirming the diagnosis.

CT (computed tomography) scan and MRI (magnetic resonance imaging) of the brain are sometimes done for identifying Lacunar Strokes. Diffusion Weighted Imaging, a specific MRI technique, is very useful for detecting these infarctions at an early stage.

Lacunar Infarct Differential Diagnosis

The differential diagnosis of this condition should ideally be done using dilated VRS or Virchow Robin spaces. In some instances, the presentation of intracranial hemorrhages and cortical infarcts can mimic the symptoms of Lacunar Infarcts. However, the true signs of cortical infarct (including visual field defects and aphasia) never occur in these types of strokes.

Lacunar Infarct Treatment and Management

The treatment depends on the severity of the symptoms and the duration of the disorder. If the treatment begins within 3 hours after the onset of the symptoms, the doctors are likely to apply a tissue plasminogen activator or clot-dissolving medication for initial treatment. Blood-thinning medications like Warfarin and Heparin are often used for treating strokes in the large arteries. But they are not used for the treatment of Lacunar Strokes.

High doses of aspirin can be administered within 48 hours of symptom onset. The treatment mainly aims to correct the underlying causes of the strokes, such as diabetes mellitus, hypertension and cigarette smoking, to reduce their recurrence chances.

Physiotherapy interventions are quite useful for Lacunar Stroke rehabilitation. Physiotherapy programs help to improve the paretic limb’s range of motion by various passive exercises of range of motion.

Severe cases of Lacunar Stroke require immediate hospitalization. The patient is then observed by the doctor to find out whether the symptoms are getting worse. Patients with severe strokes may need assistance with feeding and self-care. In the hospital, physical therapists and occupational therapists work together to help the patients cope with their disability and to regain some strength after suffering from the brain injury. Generally, patients need to stay in a rehabilitation center for some time after being discharged from the hospital for receiving some additional intensive therapy.

Lacunar Infarct Prognosis

In most cases, patients start to recover within a few hours after receiving the initial treatment. It has a better recovery rate compared to many other types of strokes involving the larger blood vessels. More than 90% of the total patients recover substantially within 3 months of suffering from the stroke for the first time. Acute Lacunar Infarcts has a higher recovery rate compared to the chronic form as they are generally diagnosed at an earlier stage.

With proper treatment, the patients recover the ability to move their body. Some stability improvements are also made. Treatment helps the patients to roll in a side-lying position, to stand and to transfer safely from one position to another (e.g. from the bed to a chair or from their wheel-chair to a car).

Lacunar Infarct Prevention

There are no assured ways for preventing this condition. However, controlling the mentioned risk factors can help one to reduce the chances of developing Lacunar Strokes. The diet and medication intake should be modified according to the recommendations of a doctor if a person has a history of heart disorders and blood pressure.

Regular exercise, eating lots of vegetables and fruits as well as avoiding foods rich in cholesterol and saturated fats help in preventing the disorder. It is important to give up smoking for reducing the risks of developing this kind of Infarction.

Lacunar Infarct Images

The following images display how this type of stroke affects the brain.

Picture 1 – Lacunar Infarct

Picture 2 – Lacunar Infarct Image

Lacunar Infarcts can be cured completely with timely diagnosis and proper treatment. However, the Silent Lacunar Infarctions cannot be detected at an early stage as they display no symptoms. But these infarctions can also be treated with proper medication and intensive therapy.