How Is Subarachnoid Hemorrhage Graded? Understanding the Hunt-Hess Scale and Its Clinical Implications

Subarachnoid hemorrhage (SAH) is a life-threatening type of stroke caused by bleeding into the space between the brain and the surrounding membranes. To assess the severity and guide treatment decisions, clinicians commonly use the Hunt-Hess grading scale, a widely accepted classification system that ranges from Grade I to Grade V. This five-tiered framework helps medical professionals evaluate neurological status, predict outcomes, and determine appropriate interventions based on symptom severity.

The Hunt-Hess Grading System: A Detailed Breakdown

Grade I – Mild Symptoms

Patients classified under Hunt-Hess Grade I typically exhibit minimal or no neurological deficits. They may experience only a mild headache or slight neck stiffness due to meningeal irritation. At this stage, consciousness remains intact, and daily functioning is largely unaffected. Despite the seemingly minor presentation, prompt diagnosis and monitoring are crucial, as early deterioration can occur without warning.

Grade II – Moderate Neurological Involvement

In Grade II, symptoms become more pronounced. Patients often suffer from severe headaches accompanied by nausea and vomiting. Meningeal signs such as nuchal rigidity (neck stiffness) are clearly present. Additionally, some individuals may show isolated cranial nerve palsies—most commonly affecting nerves responsible for eye movement—which can lead to double vision or drooping eyelids. While alertness is generally preserved, discomfort and neurological disturbances significantly impact quality of life.

Grade III – Altered Mental Status

At this intermediate level, patients begin to show signs of mental confusion, drowsiness, or lethargy. Headaches and vomiting intensify, and neurological deficits expand beyond cranial nerves to include focal impairments in motor or sensory function. These may manifest as weakness in limbs, coordination issues, or altered sensation. Although not comatose, these individuals require close observation in a hospital setting due to increased risk of clinical decline.

Grade IV – Severe Impairment and Coma

Hunt-Hess Grade IV indicates a critical condition characterized by coma ranging from mild to moderate levels of unconsciousness. Meningeal irritation and widespread neurological dysfunction are prominent. Some patients develop decerebrate posturing—a rigid extension of limbs indicating severe brainstem involvement. Vital signs may become unstable, and intensive care support becomes essential to manage intracranial pressure, respiration, and cardiovascular stability.

Grade V – Critical Condition with Poor Prognosis

This represents the most severe category, where patients are in a deep coma with no meaningful response to external stimuli. Decerebrate rigidity, brainstem failure, and loss of vital reflexes are common. Survival rates at this stage are extremely low, and even with aggressive intervention, long-term recovery is rare. The prognosis is generally poor, emphasizing the importance of rapid detection and treatment before progression to this stage.

Modifications to the Standard Grading Scale

The original Hunt-Hess scale has been supplemented to account for comorbid conditions that influence patient outcomes. When individuals present with pre-existing systemic illnesses such as hypertension, diabetes mellitus, multiple sclerosis, or chronic lung disease, their clinical grade may be adjusted upward by one level. This adjustment reflects the added physiological stress and reduced resilience associated with these conditions.

Furthermore, if cerebral angiography reveals extensive cerebral vasospasm—a dangerous narrowing of blood vessels that can lead to secondary ischemic injury—the grading is also elevated. This modification ensures a more accurate assessment of overall risk and guides therapeutic strategies, including the timing of aneurysm repair and the use of vasospasm prophylaxis.

In modern neurocritical care, the Hunt-Hess scale remains a cornerstone for initial triage and outcome prediction in subarachnoid hemorrhage. While advanced imaging and biomarkers continue to enhance diagnostic precision, this clinical grading tool provides a rapid, reliable, and practical method for evaluating patient status at presentation. Early recognition of grade progression can significantly influence management decisions and improve survival chances in this high-risk population.