Summery

Sub glottal stenosis is a laryngeal stenosis that can be congenital or acquired in origin.  The incidence is very low, however because there is not a definite treatment for the illness it's still one of the troublesome diseases in EN T field.  The most common cause of this illness is intra laryngeal trauma induced by endo-tracheal (E.T) tube. 

The objective of this study is to look at the ethiology and treatment of patient who have been admitted in Imam Khomeiny and Amir Aalam hospitals with diagnosis of sub glottal stenosis between March 1992 and September 1997. It's a retrospective study using the patient's files.  62 patients were included in this study, the youngest of which was 1.5 y/o and the oldest 76 y/o.  More than 67% of the patients were less than 25 y/o.  The most common signs were stridor and dyspnea.   In all age groups the stenosis had happened after endo-tracheal intubation and 64.4% of the cases were intubated for more than 7 days.   The patients had undergone endoscopic studies from which the most common pathologic finding was granulation tissue.  91%of the patients had to have tracheostomy tube.  43.3%of the cases had received antibiotics and corticosteroids.  Recurrence was reported in 48.3% of the patients, mostly due to granulation tissue formation after intubation.

Abstract

It was only a short while after starting to use mechanical ventilation with positive pressure in ICU units that serious and definite adverse consequences of these methods began to appear.  The severity these adverse effects was dependent on factors like the size of the E.T tube, the pressure that was induced by the calf and the duration that the tube was connected to the mechanical ventilator (BENET) machine. A patient's sub glottis is called stenotic when the biggest E.T tube that can pass it is 1/2 the normal size for the patient's age group. 

The clinical manifestations of sub glottal stenosis are variable.  It can remain asymptomatic, cause stridor and cyanosis after birth or present itself at the time of a respiratory tract infection with croup-like symptoms. 

Definite diagnosis is made by bronchoscopic laryngoscopy.  In mild cases treatment is similar to a URI, but in sever stenosis a tracheostomy tube might be needed till the full development of the airways.  In the latter cases mortality and morbidity are high.  The purpose of this study was to look at the etiology and treatment of sub glottal stenosis in the patients who were admitted with the diagnosis of the disease in Imam Khomeiny and Amir Aalam Hospitals between 1992 and 1997.

Method and Materials

This is a descriptive, retrospective study to describe the ethiology, clinical manifestations and treatment of the patient's suffering from sub glottal stenosis that was referred to Imam Khomeiny and Amir Aalam Hospitals in Tehran.  In order to gather the data needed for the study all the patient's files who were admitted in those hospitals between 1992 and 1997 were screened to find all the cases labelled as sub glottal stenosis.  Then the demographic information (age, sex, and birth place), the clinical information (chief complaint, signs, symptoms at the time of admission) and finally information regarding the treatment methods were retrieved from the files and were put in pre-designed forms.  These data were inserted in the computer where they finally were analysed by SPSS software program.

Findings

In this study 62 patients were studied among which 44 were male (70%) and 18 were female (30%).  26% of the patients were under 5, 40% between 5 and 25 and the rest were older than 25.  The youngest patient was 1.5 y/o and the oldest was 73 y/o.  All of the patients had dyspnea as one of the presenting symptoms, while only 25% of the patients had stridor.  Other signs and symptoms according to their incidence were:  voice change, dysphagia, cough, cyanosis of the lips, hoarseness, early fatigue during breast feeding and snoring since birth.  The disease could also present itself as appearing of the mentioned symptoms or their aggravation fallowing an URI in the first 3-4 months of life.

Dysphagia was seen mostly in patients with laryngeal neoplasm whiles aphonic was mostly coincided with on external trauma to larynx during a car accident.  In 81% of under 5 patients sub glottal stenosis has fallowed E.T intubation while 19% of this age group has a congenital stenosis.  The most common reason for intubation in this age group was a corrective congenital hart surgery or an ophthalmic surgery or neurosurgical procedure due to a head injury. 

In the next age group (5-25) the most common etiology was E.T intubation due to car accident and head injury.

After age 25 the most recorded etiologies were E.T intubation, laryngeal trauma, neoplastic operation or tracheostomy respectively according to their incidence.  The indication for intubation in 50% of this age group was to support the patient's respiration after a car accident and head injury, 27.5% to have various operations and the rest due to miscellaneous reasons.  

E.T intubation was lasted more than 1 week in 64% of the patients and less than a week in 12.5%.  There wasn't any recorded time for the rest. 

The diagnostic method was endoscopic study in all of the patients.  In some of the patients other methods including biopsy, CT scan and tomography were done as well as endoscopy.  The pathology findings were:  granulation tissue, tissue fibrosis, swelling of the laryngeal wall, web formation, polyp, vocal cord paralysis and increasing in sub glottal mucosal thickness. 

In 91% of these patients tracheostomy was done, the most common reason for which was in tolerance to extubation.  Laryngo Fisher operation was performed for 35% of the patients.  The other treatment methods according to their frequency order included:  stent insertion, laser therapy, granulation tissue removal, dilatation, anastomosis, tracheal resection, laryngectomy, cartilage or oral mucosal grafts, skin graft, hyoid flap, etc. 

The medical treatment included antibiotics in 66% of the patients, systemic corticosteroids in 50% and both in 43.5%.  The other treatments included cold air inhalation, O2 therapy and mucolytics. 

The patient's files were studied for recurrence incidence and overall treatment outcome.  30% of the patients after several endoscopic studies and medical treatment were registered for surgery or endoscopy fallow up.  21% of the patients didn't show any signs of recurrence of the disease.  Medical treatment was continued for these patients and tracheostomy tube was exchanged.  In 48.3% of the patients, recurrence was found from which the most common pathology findings were granulation tissue, wall edema, tissue fibrosis web formation, tracheostomy tube obstruction due to polyp discharge, progress of neoplasm and vocal cord paralysis respectively.  In these patients the original cause of stenosis were intra laryngeal trauma fallowing E.T intubation (66%), external trauma to larynx due to car accident (20%) and laryngeal neoplasm (13%).

Table 1:  Absolute and relative frequency of clinical manifestations in admitted patients with diagnosis of sub glottal stenosis in Imam Khomeiny and Amir Aalam Hospitals from 1992 to 1997.

End results

Only 7 patients after several visits and different treatments had completely recovered and the tracheostomy tube was removed.  In these patients antibiotic, corticosteroids, O2 and mucolytics were used as medical treatment.  Some of these cases had also undergone some surgical treatment like Laryngo Fisher operation, laser therapy and dilatation.

2 patients had expired.  One of them was a 5 y/o girl, a head injury case who was intubated for 21 days.  Laryngo Fisher operation and tracheostomy stent were done for her.  There were glottal and sub glottal stenosis and during dilatation procedure cardiac arrest had happened which in turn caused the patient's death. 

The other case was a 17 y/o male, a car accident and head injury case who was intubated for 7 days.  He had undergone laser therapy.  The diagnosis was sub glottal and tracheal stenosis.  He also expired after cardiac arrest during operation which was resection of trachea and end-to-end thyrotracheal anastomosis.

Discussion

Trauma to larynx, cricoid fracture and mucosal damage will cause sub glottal stenosis if are not treated properly.  In some cases E.T tube will cause the problem.  In terms of pathophysiology, the pressure that is induced by the calf will cause mucosal ischemia and cartilage necrosis which consequently will cause stenosis due to tissue repair process.  

Serious injuries are seen after 3 days of E.T intubation.  Some systemic factors are effectual including anemia, vitamin deficiency, toxicity and dehydration.  Nasogastric tube is also one of the predisposing factors.  Upper respiratory tract infection with a massive inflammatory response which can damage the mucosa, and infection in the site of a tracheostomy tube are the other factors leading to sub glottal stenosis. 

The most common presenting sign after dyspnea is stridor.  Gastrointestinal involvement with dyspnea can happen in laryngeal neoplasm.

In this study the most involved age was under 5 which show that congenital factors can cause the problem as well as trauma.  The leading cause in all age groups under 40 was E.T intubation that was mostly fallowing a car accident in under 20 y/o patients and operation in 20-40 y/o patients.  After age of 40 the most common cause was neoplasm. 

The most used diagnostic method was endoscopic study and biopsy.  The most found pathologic lesions were granulation tissue, tissue fibrosis and wall edema.  Tracheostomy tube was needed in almost all the patients.  The most performed surgical methods were Laryngo Fisher method and laser therapy.  About half of the patients were treated by antibiotics and corticosteroids.  Recurrence was seen in half of the patients as granulation tissue formation and wall edema. 

In mild and congenital sub glottal stenosis treatment includes medical therapy with antibiotics and corticosteroids, in time graft exchange and microbiologic studies to find infections and in some cases laser therapy and dilatation procedures. 

In sever cases, especially fallowing E.T intubation in head injury cases or external trauma to larynx due to car accidents, stent insertion with Laryngo Fisher operation will be needed as well as the other treatments mentioned for mild cases.  In sever cases frequent fallow up visits are crucial.

Laryngeal cancer was the etiology of 11.3% of the cases (it was reported 61.8% and 33% in two other studies.}of which  86% were laryngeal sub glottal stenosis and the rest chondrosarcoma.  All of these patients had positive history of smoking and laryngectomy was done for all of them.

The etiology of sub glottal stenosis in patients with neoplasm was as fallows:

72.7% were fallowing E.T intubation (it was reported as 48.8% and 67.5% in other studies) from which 62.4% were intubated for more than 7 days.  In 14.5% there was a history of external trauma to larynx due to a car accident.  In these patients there was a supra glottal stenosis as well as sub glottal stenosis.  In 7% of the patients tracheostomy was the cause of sub glottal stenosis (this was 31% in another study).in 5.2% of the patients the stenosis was congenital, these were less than 5 months old (13% in another study).

Recommendations

According to the findings of this study, the fallowing points should be considered in care and treatment of the patients with sub glottal stenosis.

In patients with long term tracheostomy the tube should be exchanged frequently and the secretions should be examined for bacterial growth.  Antibiotic therapy should be prescribed before and after insertion of the tracheostomy tube to prevent infection.  Patients should be advised to keep their fallow up appointments in order to have a close eye on their progress and treatment.  In the case of recurrence or to do a fallow up endoscopic study, prophylactic antibiotics and corticosteroids therapy are necessary.  Patients older than 40 should be evaluated for the presence of a laryngeal neoplasm or extension of an existing tumour.  In the early stages of stenosis the stenotic tissue should be removed as much as possible by means of laser therapy.  To avoid extra trauma to larynx the tracheostomy tube should be properly fixed.

References:

1. Paparella, A. Otolaryngology and Head and Neck Surgery.  3^rd edition USA.  Sanders. 1991. page 2085-95
2. Cummings C.A. Otolaryngology and Head and Neck Surgery.  USA. 1992. pages 122024
3. Park S.S., Streitz J.M., Rebeiz E.E., and Shapash SM, ( Title…) Arch. Otolaryngology, Head and Neck Surgery:  1995: 1210: 894-7
4. Ballenger J.J., Disease of Nose, Throat, Ear, Head and Neck,  4^th edition. 1991. page 589.
5. Fredickson C., Otolaryngology; Head and Neck Surgery; Head and Neck Surgery; 2^nd Edition. 1993. 1981-99

Published in:  The Journal of Faculty of Medicine, 57^th year, No 1
By:  Dr. Ebrahim Razmpa