Classification according to Hunt and Hess
The classification according to Hunt and Hess is based on the patient’s symptoms and is divided into grades 1 to 5. Grade 5 is the most severe form and is associated with a high probability of death. Patients with grade 1 according to this classification are quite inconspicuous and usually have only slight headaches. Patients classified as grade 5 are in a coma. The classification according to Hunt and Hess is more common than the classification according to Fisher.
Classification by Fisher
One way to classify subarachnoid hemorrhage is the Fisher classification. This is based on the CT images. There is an old and a modified variant, whereby the modified variant is divided into degrees 0 to degree 4.
The width of the hemorrhage and the bleeding into the ventricle filled with cerebrospinal fluid play a role as criteria. Grade 4 describes as the most severe form, for example, a subarachnoid hemorrhage that is wider than 1mm and has bled into a ventricle. Nowadays, the Fisher classification is no longer used as standard.
Subarachnoid hemorrhage or stroke – What are the differences?
A stroke is generally a circulatory disorder of the brain. It can be caused by a reduced blood flow (ischemia) or by excessive bleeding. The latter bleeding is often subarachnoid bleeding. These account for about 10% of all strokes. Subarachnoid hemorrhage is always a bleeding into the subarachnoid space filled with cerebrospinal fluid, which can result from a vascular sacculation or an accident with head injury.
Occurrence in the population (epidemiology)
Subarachnoid hemorrhage is part of the clinical picture of stroke (apoplexy, stroke), accounting for about 5-10% of the causes of strokes. The incidence (incidence) in industrialized countries is about 15:100. 000, most frequently affected are men and women between 40 and 60 years of age.
Anatomical bases of the human skull
In order to understand the localization, the meninges will be briefly discussed here: Meninges & fissures The outermost layer of the human skull is the so-called “scalp”, i.e. the head rind. It is visible from the outside and is usually covered by hair. Under this scalp lies the skull bone (skull calotte).
The hard cerebral membrane (dura mater, also known as pachymeninx = thick meninges) is attached to the inside of the skull. By definition, it consists of two leaves, the outer one of which is fused with the skull bone.The leptomeninx (thin or soft meninges) lies against the hard meninges from the inside. It consists of 2 parts: Arachnoidea (cobweb skin) and Pia mater (soft meninges).
The pater mater lies directly against the brain. From the outside to the inside, there are the following meninges: Although one would think that there are small gaps between all these meninges, this is normally not the case in the brain. A space between the calotte of the skull and the outer leaf of the dura mater (epidural space, “epi” – Greek: above, i.e. “space above the dura mater”) is only created when there is blood flow from a blood vessel.
The same applies to the space between the inner leaf of the dura mater and the arachnoidea (subdural space, “sub” – Latin: below, i.e. “space below the dura mater”). An exception is the space between arachnoidea and pia mater (subarachnoid space, “space under the arachnoidea”). It is always present and contains the cerebrospinal fluid (cerebrospinal fluid), which flows around the brain and spinal cord (i.e. the parts of the central nervous system).
- Dura mater with two leaves (hard meninges)
- Arachnoidea (spider web skin)
- Pia mater (soft meninges)
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