Introduction
Steroid injections have been used by dermatologists to treat skin scars since the mid-20th century, capitalizing on their antiinflammatory and scar-softening properties. This article and the accompanying figures and video explore the application of these principles to treating idiopathic subglottic stenosis (iSGS) through office-based serial intralesional steroid injections (SILSI).
iSGS is a progressive fibro-inflammatory disease that causes narrowing of the subglottic airway, leading to restricted breathing. Left untreated, it can lead to death through obstruction from the thick mucus associated with iSGS. The SILSI techniques are not unique to the treatment of iSGS; traumatic and rheumatologic (C-ANCA positive) airway scarring can also be treated with these same techniques when the cartilaginous superstructure is intact, and the scar only involves the mucosa.
Unfortunately for the women who suffer from iSGS, they are often misdiagnosed as having adult-onset asthma that is resistant to the usual asthma medications. They are seen by multiple medical professionals over time until the stridor is so impressive that it prompts visual inspection of the upper airway. This journey typically lasts several years and delays their diagnosis and eventual treatment.
Overall Treatment Rationale
Preservation and restoration of quality of life (QoL) is of paramount importance in the management of chronic diseases such as iSGS. Because SILSI offers physicians and patients the option of in-office treatment of their stenosis, it changes the treatment paradigm to one that is proactive, offering treatment at the first sign of a drop in spirometry values before symptoms begin to rob the patient of QoL. Using traditional surgical-only approaches required that the patient live with the stenosis for a while until breathing function diminished (and QoL) to justify the repeated use of general anesthetic. The ability to effectively treat stenosis in the office, coupled with the ability to track breathing using spirometry and QoL instruments over time, allows us to keep patients breathing at a very high level, maintaining their high QoL and saving them from feeling dyspneic when their stenosis recurs.
Surgical dilation of subglottic stenosis is typically performed at intervals between nine months and 15 months around the world. These surgical time intervals do not take into consideration the patient experience, which consists of several distinct stages. Immediately after surgery, patients breathe without restrictions. As the stenosis progresses, patients become aware of slight restrictions in breathing. At this point, they have crossed the “symptomatic line” and will only have more restricted breathing in the future. From here, the breathing experience gradually declines from slightly laborious during exertion to extremely laborious at rest. Patients are not offered surgery at the first sign of stridor or labored breathing, but rather must continue to decline in function before anesthesia can be justified for the next procedure. Surgery-only treatment tends to be time-based more than symptom-based ( Fig. 45.1 ).
The endoscopic surgery experience.
(A) The patient experience when treated with surgery is depicted graphically. The Y-axis is the ability to breathe ( better is towards the top of the image ), while the X-axis is time. Patients treated with dilation or endoscopic resection ( red asterisks ) typically present at advanced stages of stenosis with low ability to breathe ( red shaded areas ) and are catapulted up to great ability to breathe ( green shaded areas ) after surgery ( green asterisks ). With time, the airway begins to stenose and the ability to breathe falls, eventually requiring another procedure to open the airway. The “symptomatic line” helps to define the patient experience. Once patients cross the symptomatic line, they become progressively more dyspneic and uncomfortable. Because general anesthesia is used, the spacing between procedures tends to be time-limited rather than symptom-driven because it is not feasible to treat the stenosis at the first signs of dyspnea. (Courtesy Ramon A. Franco Jr.)
(B) The SILSI experience.
The patients begin their experience in the operating room ( red asterisk ) when breathing is compromised and breathe better after surgery ( green asterisk ), just like in the surgery-only example. In-office serial intralesional steroid injections (SILSI), depicted as 5 dashed blue lines after surgery, allow for further enhancement of the ability to breathe. Using a combination of subjective breathing symptoms, home spirometry, in-office spirometry, and quality of life (QoL) instruments, patient progress is monitored until there is a decrease in spirometry values away from baseline. This prompts an in-office evaluation and potentially resumption of a SILSI series (4–6 injections each separated by 3–4 weeks) before the patients reach the symptomatic line, thereby restoring their breathing-related QoL. (Courtesy Ramon A. Franco Jr.)
Patients are monitored at clinic visits with in-office spirometry and between visits with home spirometry. They test themselves multiple times a month, where they establish their baseline peak expiratory flow (PEF). These days, home digital spirometers can be obtained that connect to cell phones via Bluetooth and keep track of the spirometry values. These can be obtained for under $150.
When there is a decline from their baseline, they contact the office and are evaluated with in-office spirometry that is coupledto any symptomatic changes in breathing effort or increased mucus. Patients initially see a decline in spirometry values before they become overtly symptomatic. The decision to treat vs close observation is dependent on the degree to which symptoms have returned or the magnitude of the drop in spirometry values (without a good explanation for the drop, such as a recent upper respiratory infection or pneumonia).
Steroids and Scars
Wound healing consists of multiple steps beginning with inflammation, leading to cell proliferation, and finally wound remodeling. Steroids modify each step of wound healing. Dermatologists have known since the 1950s that steroids injected into scars can cause regression of the scar and a more pleasing cosmetic appearance to the skin. This typically needs to be repeated multiple times to create the best effect. This is the basis for the repeated injections of steroids we have historically performed to treat keloids. The molecular pathways involved in scarring are consistent across different tissues, including the subglottis. Steroids disrupt these pathways in skin by reducing inflammation, suppressing new scar formation, and enhancing the breakdown of existing scars through the activation of matrix metalloproteases (collagenases). The same effects have been shown in the subglottis of iSGS patients undergoing SILSI. Even after one steroid injection, there is a significant reduction in inflammation that leads to a reduction in the number of fibroblasts and destruction of existing collagen fibers.
Methods
Patient Evaluation
A breathing problem requires a breathing test. Forced Spirometry is a validated tool critical for tracking patients and the effectiveness of SILSI ( Fig. 45.2 ). Parameters like PEF and peak inspiratory flow (PIF) serve as good indicators of airway status. Unfortunately, these raw numbers only have meaning for a particular patient as they are dependent on the patient’s gender, weight, age, and height. A 20-year-old 6′3″ male is expected to have much larger raw PEF and PIF values compared to an 80-year-old 5′1″ woman. Despite her lower numbers, the woman may be exceeding her expected values, while the man may be underperforming and having breathing problems, despite his larger raw spirometry values. The PEF% is a normalized value that considers these variables and allows for comparisons between patients. Spirometry has been shown to correlate with symptomatic improvements after airway interventions and QoL measures. , Spirometry is much more reliable and offers reproducible results compared to endoscopic grading of airway size.
In-Office forced spirometry.
Forced spirometry is an important tool in the evaluation and treatment of patients with idiopathic subglottic stenosis. The patient forcefully breathes into the single-use mouthpiece while the hand-held spirometer records the raw peak inspiratory and peak expiratory flow (PEF). A flow-volume loop is plotted. The spirometer uses the patient’s age, sex, weight, height, and smoking status to calculate the PEF% value. This PEF% can be used to keep track of the patient’s breathing status. It cannot be overstated how much proper and aggressive coaching is necessary to get the best and most consistent effort from patients during forced spirometry.
(Courtesy Ramon A. Franco Jr.)
Patient Preparation for In-Office Injections
The medical history is reviewed with careful attention paid to any recent changes to breathing effort and home spirometry values, and any recent changes to mucus consistency and amount. Although most patients (95%) successfully undergo awake in-office steroid injections, the physician must evaluate and determine that the patient has a good chance of completing the procedure. Previous history of ability to tolerate awake in-office injections, as well as nonverbal cues that would suggest the patient is too nervous, are taken into consideration when determining the appropriateness for in-office awake SILSI.
Forced spirometry is performed before giving the patient any anesthetic ( Fig. 45.2 ). It is important to motivate the patient to give as much respiratory effort as possible, as spirometry is only a semiobjective measure and is influenced by the patient’s level of cooperation and level of effort. We use a digital handheld spirometer and ask the patient to complete three sets of three complete expiratory and inspiratory loops (9 total loops). This is where we derive our PEF, PIF, and PEF percentage numbers ( Fig. 45.3 ).
Forced spirometry.
(A) Flow-volume loop of a patient with significant subglottic stenosis. Notice the “box-like” shape of the flow-volume loop. The expiratory limb is above the X-axis, whereas the inspiratory limb is below the X-axis. (Courtesy Ramon A. Franco Jr.)
(B) The various indices that are recorded and calculated by the spirometer. We can see that the peak expiratory flow (PEF) is 2.65 L/sec. This translates to 40% of the predicted. The peak inspiratory flow (PIF) is also reduced and stands at 1.64 L/sec. (Courtesy Ramon A. Franco Jr.)
(C) Posttreatment, the flow-volume loop shows significant improvement with the appearance of a sharp peak in the expiratory limb ( above the X-axis ) and a rounded appearance of the inspiratory limb ( below the X-axis ). (Courtesy Ramon A. Franco Jr.)
(D) Posttreatment, the peak expiratory flow (PEF) and peak inspiratory flow (PIF) have been restored to the normal values of 6.09 L/sec and 5.64 L/sec, respectively. The PEF of 6.09 L/sec translates to 92% of the predicted. (Courtesy Ramon A. Franco Jr.)
