Parenchymal brain hemorrhage, also known as intraparenchymal hemorrhage (IPH), refers to bleeding that occurs within the functional tissue of the brain, encompassing neurons and glial cells. This type of hemorrhage arises from the rupture of blood vessels in the brain, disrupting the regular blood flow and resulting in oxygen deprivation to the brain. Consequently, the affected nerves and their associated functions may be compromised, leading to cell death. Spontaneous IPH comprises less than 20% of stroke cases but is linked to the highest mortality rates among all stroke types. IPH can be categorized as either primary or secondary based on its cause. Primary IPH, constituting approximately 80% of cases, occurs when damaged arteries spontaneously rupture. On the other hand, secondary IPH is associated with an underlying condition that increases the risk of hemorrhage.
The classification of parenchymal hemorrhage, particularly in the context of the brain, can be based on various factors, including etiology and severity. Here is a breakdown:
- Primary Parenchymal Hemorrhage: Hemorrhage that occurs spontaneously without an identifiable underlying cause. This may include cases related to hypertension or cerebral amyloid angiopathy.
- Secondary Parenchymal Hemorrhage: Hemorrhage that occurs as a result of an underlying condition or factor. This can include coagulopathy, sickle cell disease, brain tumors, cerebral venous sinus thrombosis, arteriovenous malformation, Moyamoya disease, and other vascular abnormalities.
- Intracerebral Hemorrhage (ICH): Hemorrhage that occurs within the cerebral parenchyma. This can be further classified based on the specific brain region affected.
- Intraventricular Hemorrhage (IVH): Hemorrhage that occurs into the brain’s ventricular system.
- Small, Moderate, or Large Parenchymal Hemorrhage: This classification is based on the size and extent of the hemorrhage within the brain tissue.
- Massive Parenchymal Hemorrhage: Used to describe extensive and severe hemorrhages that may result in significant neurological consequences.
Clinical Course Classification:
- Acute Parenchymal Hemorrhage: Refers to hemorrhages with a sudden onset of symptoms.
- Chronic Parenchymal Hemorrhage: Describes hemorrhages that develop over a more extended period, often with subtle or gradual symptom onset.
It’s important to note that the classification of parenchymal hemorrhage can be complex, and individual cases may involve a combination of these classifications. Additionally, ongoing research may lead to refinements in the classification system as our understanding of the underlying mechanisms and factors influencing parenchymal hemorrhage continues to evolve.
Etiology and risk factors
Etiology, or the study of the causes of intraparenchymal hemorrhage (IPH), reveals various factors contributing to this condition. Primary IPH, often linked to high blood pressure or hypertension, raises the risk of rupturing small vessels within the brain parenchyma. Another cause is cerebral amyloid angiopathy (CAA), where abnormal proteins (amyloids) accumulate on brain artery walls, leading to rupture and subsequent hemorrhage.
In contrast, secondary IPH may result from diverse underlying conditions. Coagulopathy, characterized by the inability to form blood clots due to deficiencies in coagulation factors or severe platelet deficiency (thrombocytopenia), is a common cause. Additionally, sickle cell disease, a hereditary disorder altering red blood cell shape, brain tumors, cerebral venous sinus thrombosis (CVST), arteriovenous malformation can contribute to secondary IPH.
The array of reasons for hemorrhage encompasses hypertension, arteriovenous malformation, amyloid angiopathy, aneurysm rupture, tumor, coagulopathy, infection, vasculitis, the use of sympathomimetic drugs like amphetamines, and trauma, among others. Hypertension remains the most common risk factor, with other significant contributors including amyloid angiopathy, advanced age, anticoagulant use, alcohol intake, smoking, specific cholesterol levels.
The manifestation of a parenchymal hemorrhage is often accompanied by distinctive signs and symptoms. Common indicators include headaches, seizures, and focal neurological deficits affecting speech, vision, and hearing. The severity and nature of these symptoms can vary depending on the specific location of the bleed within the brain. Additionally, individuals may experience nausea and vomiting, lethargy, limb weakness, and sensory defects, such as numbness in the face and limbs. In cases of larger bleeds, impaired consciousness may be evident.
Noteworthy symptoms associated with intraparenchymal hemorrhage encompass:
- Acute onset focal neurological deficit
- Altered sensorium
Important! The presence of nausea, vomiting, headache, and decreased level of consciousness tends to indicate hemorrhage rather than ischemic stroke. Seizures are more commonly observed in intraparenchymal hemorrhage secondary to venous sinus thrombosis or cavernous malformation compared to other causes. Secondary intraparenchymal hemorrhage, especially due to venous sinus thrombosis and vascular malformations, typically presents at a younger age, with no history of hypertension.
During a physical examination, clinicians may observe:
- Lower than normal Glasgow Coma Scale (GCS)
- Hemisensory loss
- Bradycardia or tachycardia
- Gaze palsy
- Facial palsy
In severe cases, the resulting brain damage can lead to physical or mental disability, underscoring the importance of prompt medical attention and intervention.
The diagnosis of parenchymal hemorrhage involves a comprehensive approach, incorporating various diagnostic procedures and studies. Blood coagulation studies, specifically analyzing partial thromboplastin time (PTT) in a blood sample, are often necessary to assess the clotting time. Imaging studies, such as computerized tomography (CT) scans of the head, play a crucial role in visualizing bleeds in different areas of the brain. Computed tomographic angiography/venography, entailing the injection of radiographic dye into blood vessels leading to the brain, can aid in identifying cerebral venous sinus thrombosis (CVST). Magnetic resonance imaging (MRI) is another valuable tool, allowing for the detection of underlying causes like brain tumors or ischemic strokes. Additionally, MRI can reveal patterns consistent with cerebral amyloid angiopathy (CAA) or high blood pressure.
Supplementary studies may include cardiopulmonary monitoring and electroencephalogram (EEG). These assessments respectively evaluate heart and lung function and rule out alternative diagnoses such as seizures.
Differential diagnoses for intracranial hemorrhage encompass:
- Infection – Subdural empyema may resemble a subdural hemorrhage.
- Recent contrast administration.
- Subdural hygroma – Can exhibit similarities to chronic subdural hemorrhage.
- Tumors – Meningioma may mimic an extradural hemorrhage.
Considering the complexity of these diagnoses, a thorough evaluation and collaboration of multiple diagnostic modalities are essential for accurate identification and appropriate management.
Prevention and treatment
The prevention and treatment of parenchymal hemorrhages are crucial due to their potential life-threatening nature. Timely intervention is essential, focusing on maintaining adequate blood pressure and normal intracranial pressure in individuals with intraparenchymal hemorrhage (IPH). If intracranial pressure rises, medications such as mannitol or hypertonic saline may be administered. Identifying and addressing the underlying cause of the IPH is equally important. For secondary IPH resulting from coagulation factor deficiency or thrombocytopenia, factor replacement therapy or platelet therapy is recommended. If the individual is on anticoagulation or blood-thinning medications, the administration of vitamin K or protamine sulfate may be necessary to reverse the effects of these medications.
In cases where an individual becomes unresponsive due to the hemorrhage, airway management becomes imperative to mitigate the risk of secondary injury from aspiration, hypoxemia (severely decreased oxygen levels in the blood), and hypercapnia (excessive carbon dioxide in the blood).
For parenchymal hemorrhages occurring in the cerebellum, which is in a confined space near the brainstem, cerebellar decompression surgery may be indicated. Minimally invasive approaches may involve small incisions, burr holes, and the insertion of a catheter into the clot for drainage. Alternatively, an open craniotomy, involving the surgical removal of part of the skull, may be performed to treat certain parenchymal hemorrhages.
Long-term control of blood pressure is paramount in preventing recurrent intraparenchymal hemorrhages. A target blood pressure of less than 130/80mmHg is recommended.
Alongside blood pressure control, lifestyle measures such as smoking cessation, avoiding illicit drug use, and moderating alcohol intake can contribute significantly to preventing recurrence.
Intracranial Hemorrhage: https://emedicine.medscape.com/article/1163977-overview#a5 Intraparenchymal hemorrhage: https://www.wikidoc.org/index.php/Intraparenchymal_hemorrhage Intracranial haemorrhage: https://www.ncbi.nlm.nih.gov/books/NBK470242/
Parenchymal haemorrhage: https://www.osmosis.org/answers/parenchymal-hemorrhage https://touchneurology.com/stroke/journal-articles/classification-of-intracerebral-haemorrhages/