The Thompson Score is a clinical tool used by neonatologists to quickly and objectively assess the neurological status of newborns who have suffered from perinatal asphyxia. This condition, which involves a lack of oxygen and/or blood flow to the infant’s brain around the time of birth, leads to a form of brain injury called Hypoxic-Ischemic Encephalopathy (HIE). The score provides a standardized method for quantifying the severity of this neurological impairment, moving beyond subjective clinical impressions to generate a numerical value. By offering a precise measure of central nervous system dysfunction, the Thompson Score guides time-sensitive medical decisions for these vulnerable infants.
What the Thompson Score Measures
The Thompson Score evaluates the neurological function of a newborn through a focused examination of several key areas associated with central nervous system activity. It assesses nine distinct clinical signs, each reflecting a different aspect of brain function. These signs include the infant’s muscle tone, their level of consciousness, and the presence or frequency of seizure activity.
Other parameters assessed include the infant’s spontaneous posture, the strength of their primitive reflexes such as the Moro response and grasping reflex, and their ability to suck. The score also factors in autonomic functions like the pattern of respiration and the tension of the anterior fontanelle. Each of the nine criteria is graded on a scale, typically from 0 to 3, where 0 indicates a normal finding. The points from all categories are then summed to produce a single total score, with the maximum possible score being 22.
Grading the Severity of HIE
The total numerical value derived from the assessment translates into a clinical diagnosis that grades the severity of the infant’s Hypoxic-Ischemic Encephalopathy. This grading is critical for both communicating the infant’s status and predicting their immediate needs. The score ranges correspond to three distinct clinical stages: Mild, Moderate, and Severe HIE.
A score ranging from 0 to 10 is categorized as Mild HIE, where the infant may exhibit subtle neurological signs such as hyper-alertness or irritability. Infants falling into the Moderate HIE category typically have a score between 11 and 14, often presenting with pronounced symptoms like lethargy, hypotonia (reduced muscle tone), and sometimes infrequent seizures. The most serious diagnosis is Severe HIE, indicated by a score of 15 or higher (up to the maximum of 22), where the infant is often stuporous or comatose, may have flaccid muscle tone, and frequently experiences severe or prolonged seizures. This numerical classification system allows healthcare providers to quickly identify the degree of brain injury.
Using the Score to Determine Treatment
The Thompson Score’s most impactful application is its role in determining an infant’s eligibility for therapeutic hypothermia, commonly known as cooling. This neuroprotective treatment is time-sensitive, as it must be initiated within the first six hours after birth to be most effective. Clinical protocols typically reserve this treatment for infants who have established Moderate HIE, as those with Mild HIE generally have a good prognosis without intervention.
Infants who score within the Moderate HIE range (around 11 to 14) are the primary candidates for this intervention, which involves lowering the infant’s core body temperature by three to four degrees Celsius for 72 hours. The score, combined with other criteria like gestational age and evidence of perinatal hypoxia, helps clinicians make the rapid decision to initiate cooling protocols. The score is consistently used to identify the infants who are sick enough to benefit from cooling but not so severely injured that the treatment would be futile. For those with Severe HIE (scores of 15 or greater), the potential benefit of cooling is often lower, and they face a significantly increased risk of mortality or severe disability.
The Thompson Score and Long-Term Outlook
Beyond guiding immediate treatment, the Thompson Score serves as a tool for predicting the long-term neurodevelopmental outlook for infants who have suffered HIE. A higher score is correlated with an increased probability of an adverse outcome, even in the era of therapeutic hypothermia. For example, studies have shown that a score of 15 or greater is associated with a poor neurodevelopmental outcome, such as the development of cerebral palsy or severe cognitive impairment, at one year of age.
While the score is a powerful predictor, it is not an absolute guarantee of a specific outcome. However, the initial Thompson Score helps identify which infants will require prolonged follow-up care and early intervention services. Regular monitoring of neurodevelopment is recommended for all infants who experienced Moderate or Severe HIE, regardless of whether they received therapeutic hypothermia.