Differentiation of Exterior and Interior Patterns
【Differentiation of Exterior and Interior Patterns】
The differentiation of exterior and interior is a fundamental principle for identifying the location and depth of diseases. The concepts of “exterior” and “interior” are relative; for instance, the body shell is considered exterior while the internal organs are considered interior. Similarly, the “fu” (腑) organs are exterior compared to the “zang” (脏) organs, and the meridians are exterior compared to the internal organs. In the context of the three yang meridians and three yin meridians, the three yang meridians are considered exterior while the three yin meridians are considered interior. The skin is exterior compared to the muscles and bones, which are interior. Therefore, the understanding of the location and depth of diseases should not be absolute.
Generally speaking, from the perspective of disease location, the skin, muscles, and meridians are considered exterior, while the internal organs and bone marrow are considered interior. Thus, from a certain perspective, diseases located externally are classified as exterior and are generally milder, while diseases located internally are classified as interior and are generally more severe. In terms of disease progression, when an external pathogen enters the interior, the disease becomes more severe; conversely, when the pathogen exits the interior to the exterior, the disease becomes milder. Therefore, ancient practitioners recognized that when a pathogen enters the interior, the disease deepens, and when it exits to the exterior, the disease lightens.
Any differentiation of disease should consider the exterior and interior locations, which is particularly important for external diseases. This is because the symptoms of internal injuries and miscellaneous diseases generally belong to the category of interior patterns, making the differentiation of exterior and interior less critical, with a primary focus on identifying the specific internal organs involved. However, external diseases often exhibit a progression from exterior to interior, from mild to severe, and from superficial to deep. Therefore, the differentiation of exterior and interior patterns is the most basic understanding of the developmental stages of external diseases, indicating the severity and depth of the condition and the trend of pathological changes, thus allowing for better management of disease evolution. In a certain sense, the differentiation of the six meridians and the differentiation of defensive qi, nutritive qi, and blood can be understood as classification methods based on the layers of exterior and interior severity.
【Exterior Pattern】
The exterior pattern refers to the superficial symptoms caused by the invasion of external pathogens such as the six excesses, epidemics, and insect toxins, which are resisted by the body’s righteous qi (卫气, wei qi). The exterior pattern is primarily observed in the early stages of external diseases.
Clinically, exterior patterns generally present with sudden onset, milder symptoms, and a shorter duration, with identifiable factors of external pathogen exposure. The main manifestations include chills (or aversion to wind), fever (or subjective feeling of no fever), headaches, body aches, floating pulse, and thin white tongue coating, or symptoms such as nasal congestion, clear nasal discharge, sneezing, itchy throat, and mild cough. These symptoms arise from the external pathogen obstructing the normal dispersal of the defensive qi at the skin and muscles.
Although there are various types of external pathogens, the symptoms of exterior patterns can vary, but they generally share the common characteristics of sudden onset of chills and fever, with no significant internal organ symptoms.
Common clinical exterior patterns include wind-cold exterior pattern, wind-heat exterior pattern, wind-damp exterior pattern, dryness exterior pattern, summer-heat damp exterior pattern, and wind-attack exterior pattern.
Due to the superficial location and mild nature of exterior patterns, which are generally of a solid nature, they can usually be cured relatively quickly. If the external pathogen is not resolved, it may further penetrate inward, leading to a half-exterior half-interior pattern or an interior pattern.
【Interior Pattern】
The interior pattern refers to symptoms arising from pathological changes within the body, involving the internal organs, qi, blood, and bone marrow.
In contrast to exterior patterns, the concept of interior patterns is very broad and can be said that any specific symptoms that are not classified as exterior patterns (or half-exterior half-interior patterns) generally fall under the category of interior patterns, hence the saying “non-exterior is interior.” Interior patterns are more commonly seen in the middle and later stages of external diseases or in cases of internal injuries. The causes of interior patterns can generally be categorized into three situations: first, an external pathogen invades the exterior, and if the exterior pattern does not resolve, the pathogen penetrates inward, forming an interior pattern; second, an external pathogen directly enters the interior, affecting the internal organs; third, emotional distress, dietary issues, or overexertion directly harm the internal organs, or cause disharmony in the qi mechanism, leading to various symptoms related to qi, blood, and body fluids.
The range of interior patterns is extremely broad; although they all belong to the interior, there are still distinctions in depth. Generally, pathological changes in the fu organs, upper body, or qi are milder, while those in the zang organs, lower body, or blood are more severe.
Different interior patterns can present with various symptoms, making it difficult to pinpoint specific representative symptoms of interior patterns. However, their basic characteristics include the absence of sudden onset chills and fever, with internal organ symptoms being the primary manifestations. The onset can be acute or chronic, and the disease is generally more severe with a longer duration.
Interior patterns can be classified into cold, heat, excess, and deficiency patterns according to the eight principles. The specific differentiation of interior pattern symptoms must be combined with the differentiation of internal organs, six meridians, and the differentiation of defensive qi, nutritive qi, and blood to clarify the diagnosis further.
Due to the complex causes of interior patterns, their broad range, and the generally more severe nature of the disease, treatment methods are more varied and generally not as straightforward or effective as those for exterior patterns.
【Half-Exterior Half-Interior Pattern】
The half-exterior half-interior pattern is commonly referred to as Shaoyang disease in the differentiation of the six meridians. It refers to the symptoms that arise during the process of an external pathogen entering the interior, where the righteous and evil forces are in contention, and the Shaoyang pivot is not functioning properly, resulting in symptoms that reflect the transitional state between exterior and interior.
【Key Points for Differentiating Exterior and Interior Patterns】
The differentiation between exterior and interior patterns primarily involves examining symptoms of cold and heat, the prominence of internal organ symptoms, changes in tongue appearance, pulse characteristics, and other factors. According to the “Heart Understanding of Medicine: Differentiation of Cold and Heat, Deficiency and Excess, Exterior and Interior, Yin and Yang,” it states: “The differentiation of exterior and interior in a disease is entirely based on the presence of fever and tidal heat, chills and aversion to heat, headache and abdominal pain, nasal congestion and dry mouth, the presence or absence of tongue coating, and the floating or sinking pulse. If there is fever and aversion to cold, headache and nasal congestion, and the tongue has no coating (or is thin white), the pattern is exterior; if there is tidal heat and aversion to heat, abdominal pain and dry mouth, the tongue coating is yellow and black, and the pulse is sinking, the pattern is interior.”
Generally speaking, in external diseases, the simultaneous presence of fever and aversion to cold indicates an exterior pattern; however, if there is fever without aversion to cold or cold without fever, it indicates an interior pattern; alternating cold and heat indicates a half-exterior half-interior pattern. Exterior patterns commonly present with symptoms such as headaches, body aches, nasal congestion, or sneezing, with no significant internal organ symptoms; interior patterns primarily manifest with internal organ symptoms such as cough, shortness of breath, palpitations, abdominal pain, and diarrhea, while symptoms like nasal congestion and body aches are not common; half-exterior half-interior patterns exhibit unique symptoms such as fullness and discomfort in the chest and flanks. Changes in tongue coating are not significant in exterior and half-exterior half-interior patterns, while interior patterns often show significant changes in tongue coating; exterior patterns typically present with a floating pulse, while interior patterns often present with a sinking pulse or other various pulse characteristics. Additionally, the differentiation of exterior and interior patterns should also consider the onset speed, severity of the condition, and duration of the disease.
【Exterior and Interior Transitions】
During the progression of a disease, due to the contention between righteous and evil forces, if the exterior pattern does not resolve, it can penetrate inward and transform into an interior pattern, referred to as exterior pattern entering the interior; conversely, certain interior patterns may allow the pathogenic factors to emerge outward, referred to as interior evil exiting the exterior. Understanding the transitions between exterior and interior patterns is crucial for predicting the development and outcome of diseases, timely adjusting treatment methods, and effectively managing the disease progression.
Exterior pattern entering the interior refers to the initial presence of an exterior pattern, followed by the emergence of an interior pattern, with the exterior pattern subsequently disappearing, indicating the transformation of the exterior pattern into an interior pattern due to the entry of external pathogens. For example, when the external pathogen of wind-heat causes an exterior heat pattern, if the exterior pathogen is not resolved, it can lead to an interior heat pattern. This transition is generally observed in the early to middle stages of external diseases, reflecting the progression of the disease from superficial to deep.
Interior evil exiting the exterior refers to the pathogenic factors within the interior that have the potential to emerge outward, indicating a favorable trend for recovery. For instance, in children with measles, if the heat toxin is trapped internally, the rash does not emerge, leading to symptoms such as fever, cough, and irritability; however, if the measles toxin emerges outward, the rash appears, and the fever and cough subside. In external warm diseases, the interior heat pattern characterized by high fever and thirst can improve with sweating, leading to a reduction in fever and a cooling of the body; when heat enters the nutritive and blood levels, the appearance of rashes and the reduction of fever, delirium, and irritability can be observed. Similarly, when damp-heat in the liver and gallbladder manifests as jaundice, the symptoms of fullness and pain in the flanks, fever, and nausea can improve. Deep-seated abscesses that rupture outward and drain pus are also considered instances where the interior pathogenic factors have the potential to emerge outward. However, this does not indicate a transformation of the interior pattern into an exterior pattern.
