Hunt and Hess Scale for Subarachnoid Hemorrhage Calculator

How does this Hunt and Hess scale for subarachnoid hemorrhage calculator work?

This is a health tool that evaluates the severity of subarachnoid hemorrhage based on the presentation symptoms of the patient.

There are 5 categories in the scale developed by Hunt and Hess, two neurosurgeons from the US in 1968. The aim is to obtain a mortality/ survival percentage to be used in predicting the outcome of each individual case.

The Hunt and Hess scale for subarachnoid hemorrhage calculator explains the criteria as follows:

■ Grade I:

- Asymptomatic or mild headache, slight nuchal rigidity.

- 30% mortality risk or 70% survival rate.

■ Grade II:

- Cranial nerve palsy or moderate to severe headache/nuchal rigidity.

- 40% mortality risk or 60% survival rate.

■ Grade III:

- Mild focal deficit, drowsiness, lethargy, or confusion.

- 50% mortality risk or 50% survival rate.

■ Grade IV:

- Stupor and/or moderate-severe hemiparesis.

- 80% mortality risk or 20% survival rate.

■ Grade V:

- Deep coma, decerebrate posturing, moribund appearance.

- 90% mortality risk or 10% survival rate.

The scale can be used in all patients suffering from subarachnoid bleeding who have been neurologically consulted and admitted in hospital, without any age, gender or comorbidities restrictions.

The only criticism received by the method is related to the small differentiation between grade I and grade II although there is a big difference between the mortality rates predicted by the two.

The Hunt and Hess grading system predicts a poorer outcome in patients with non-traumatic SAH as defined in the Hunt and Hess classification introduced based on clinical conditions and the correlation with patient symptoms. Higher grades on the scale correlated to higher risks of mortality.

Subarachnoid hemorrhage (SAH) guidelines

This is one of the spontaneous atraumatic intracranial bleedings that occurs usually because of aneurysmal or arteriovenous malformation AVM leakage or rupture but can also occur due to hemorrhage within the brain tissue (parenchyma).

As intracranial aneurysms are the most likely cause in non traumatic patients, these cases are often life threatening, with 15-30% of patients dying before reaching the hospital and another 25% during the first 24 hours of hospitalization, so they require constant monitoring and sensitive methods of prognostic.

Some of the most common risk factors for brain aneurysms include old age, hypertension, arteriosclerosis, alcohol consumption, smoking, substance abuse and the low levels of estrogen in females at menopause.

There are also premonitory symptoms that often precede a SAH such as headaches, dizziness, orbital pain, visual impairment or loss, sensory or motor disturbance or dysphasia. Presentation symptoms of SAH include blood pressure elevation, tachycardia, papilledema, retinal hemorrhage and neurological impaired function.

Methods of investigation include vascular imaging, used to check for any signs of aneurysmal cerebral bleeding and to prevent other complications is necessary as well as CT determinations to evaluate the amount of blood.

Surgery is often used to prevent the blood travelling (extravasation) into the subarachnoid space between the pial and arachnoid membranes something that will in turn affect the brain function, lead to severe complications including death.

The factors that are used in prognostic are the severity of the hemorrhage, the degree of cerebral vasospasm, the occurrence of another bleeding episode and even the existence of other comorbidities and lifestyle risk factors.

There are other clinical assessment scales similar to Hunt and Hess for the prognostic, the World Federation of Neurological Surgeons (WFNS) grading system and the Fischer scale, both presented below:

■ The WFNS scale is correlated with the Glasgow coma scale number of points obtained in the neurological assessment:

- Grade 1 - GCS of 15 without any motor deficit;

- Grade 2 - GCS of 13-14, motor deficit absent;

- Grade 3 - GCS of 13-14, motor deficit present;

- Grade 4 - GCS of 7-12, motor deficit absent or present;

- Grade 5 - GCS of 3-6, motor deficit absent or present.

■ The Fisher scale based on CT scan findings has 4 classifications:

- Group 1 - No blood detected;

- Group 2 - Diffuse deposition of subarachnoid blood, no clots, and no layers of blood greater than 1 mm;

- Group 3 - Localized clots and/or vertical layers of blood 1 mm or greater in thickness;

- Group 4 - Diffuse or no subarachnoid blood, but intracerebral or intraventricular clots present.

References

1) Hunt WE, Hess RM. (1968) Surgical risk as related to time of intervention in the repair of intracranial aneurysms. J Neurosurg; 28(1):14-20.

2) Degen LA, Dorhout Mees SM, Algra A, Rinkel GJ. (2011) Interobserver variability of grading scales for aneurysmal subarachnoid hemorrhage. Stroke; 42(6):1546-9.

3) Rosen DS, Macdonald RL. (2005) Subarachnoid hemorrhage grading scales: a systematic review. Neurocrit Care; 2(2):110-8

4) Weir RU, Marcellus ML, Do HM, Steinberg GK, Marks MP. (2003) Aneurysmal subarachnoid hemorrhage in patients with Hunt and Hess grade 4 or 5: treatment using the Guglielmi detachable coil system. AJNR Am J Neuroradiol; 24(4):585-90.