HIPPOKRATIA 2012, 16, 4: 324-328

ORIGINAL ARTICLE

Stroboscopy for benign laryngeal pathology in evidence based health care

Printza A1, Triaridis S2, Themelis C1, Constantinidis J1
2 Otorhinolaryngology Department, Medical School, Aristotle University of Thessaloniki, Papageorgiou Hospital,
1 nd

Thessaloniki, Greece
1 Otorhinolaryngology Department, Medical School, Aristotle University of Thessaloniki, AHEPA Hospital, Thes-
2 st

saloniki, Greece

Abstract
Background and aims: Voice disorders are common. The aim of this study is to evaluate the diagnostic value of stro-
boscopy for voice disorders related with benign pathology and apply results in evidence based health care.
Methods: Prospective study. Tertiary care hospital. Voice Clinic. One hundred and fifty consecutive patients with an
initial diagnosis of benign laryngeal disease or dysphonia of no clarified cause (normal laryngoscopy) were examined
stroboscopically and studied prospectively until a final diagnosis was reached. Sixty-six men, eighty women and four
children met the selection criteria for the study and had adequate follow-up. The initial laryngoscopic diagnosis was
compared to the stroboscopic diagnosis. The diagnostic value of stroboscopy was rated at a scale of 0 to 3. A score 3
describes the diagnostic value of stroboscopy in the cases where the stroboscopic examination resulted to a change of
the therapeutic modality offered to the patient.
Results: For one third of the study’s population the diagnostic value of stroboscopy was very significant, since it estab-
lished the laryngeal pathology responsible for the voice disorder (28.8%) and for a small number of patients it changed
the choice of treatment (4.7%). For about one third of the cases (32.2%) stroboscopy offered additional information
regarding the cause of dysphonia. The diagnostic value of stroboscopy correlated with the type of laryngeal pathology.
Conclusions: Patients expected to benefit from stroboscopic examination are patients with small lesions of the vocal fold edge,
dysphonic patients with unremarkable indirect laryngoscopy, and professional voice users. Hippokratia 2012, 16, 4: 324-328

Key words: stroboscopy, voice disorders, dysphonia, diagnosis, health care, evidence based
Corresponding author: Dr Athanasia Printza, 215 Labraki street, 54352, Thessaloniki, Greece, e-mail: nan@med.auth.gr

Introduction differ between different countries but cost - conscious

Stroboscopy constitutes part of a multidimentional health services globally are attempting to base decisions
approach which has been adopted in the systematic study on indications of cost effective use of diagnostic modali-
of voice disorders1. Its clinical value has been reported to ties. The diagnostic value of any examination in clinical
be the improved diagnosis of benign vocal fold lesions, practice is based on the ability to offer added information
vocal fold scars, muscle tension dysphonia and early in- in a valid, repeatable, practical, cost-effective way. Stro-
vasive lesions2-4. Voice disorders are common5. In most boscopy is more time consuming than standard indirect
of the cases patients are treated by non voice specialized laryngoscopy4. Stroboscopes are available in voice clin-
otolaryngologists. Diagnosis is the basis of treatment de- ics, the examination is performed by voice specialists and
cisions. Previous studies have demonstrated a significant is not reimbursed in our health system. The aim of this
inter-observer variability in the diagnosis by non voice study was to evaluate the diagnostic value of stroboscopy
specialists viewing laryngoscopic videos6. This variabil- in clinical practice when treating patients with benign
ity can be reduced by stricter definitions of diagnoses, laryngeal pathologies, so that access to specialized diag-
training in voice clinics and use of improved diagnostic nostics can be offered in a cost effective manner.
technology6. Treatment of voice disorders should aim to
satisfy each patient’s unique vocal requirements. Severe Participants and methods
dysphonia influences an individual’s health related qual- Participants to the study were all consecutive patients
ity of life and effective treatment, based on the correct attending the Voice or the ENT Clinic of a tertiary care
diagnosis, improves patients’ perceptions about their hospital over a year, with a prior laryngoscopy that yield-
quality of life7. ed a diagnosis of benign laryngeal disease or dysphonia
Health service organisational issues influence the ac- with normal laryngoscopic findings. Laryngoscopy had
cess of patients to voice specialists and to improved diag- been performed with laryngeal mirror, laryngeal tele-
nostic technology. Billing and reimbursement guidelines scope or flexible rhinopharyngolaryngoscope by board
 HIPPOKRATIA 2012, 16, 4 325

Table 1: Laryngoscopic examination.

Glottis morphology at inspiration
Morphology and movement of arytenoids
Vocal fold morphology: upper surface - vocal fold edge - anterior commissure
Sustained vowel phonation /e/, /i/
False vocal folds - ventricles
Table 2: The phonetory measures of the study’s population.
MPT <10 seconds for 8 patients
VHI 1 to 104 (mean: 37, SD: 27.3)
GRBAS dysphonia rating 0 to 3 (mean: 1.4, SD: 1)
MPT: Maximum Phonation Time, VHI: Voice Handicap Index.

Table 3: Stroboscopic value for different pathologies. Kruskal-Wallis analysis of variance by rank.
Diagnosis N Mean Rank
Vocal fold cyst 5 88,90
Muscle tension dysphonia 5 85,50
Vocal fold atrophy 14 69,18
Nodules 28 59,07
Vocal fold polyp 15 48,40
Chronic laryngitis 8 41,69
Vocal fold paresis 14 39,79
Reinke’s edema 16 28,38

Table 4: The strobocopic diagnoses in patients with unremarkable laryngoscopy.

Stroboscopic diagnosis n DVS*
Muscle tension dysphonia 5 2
Vocal fold oedema 9 2
Vocal fold atrophy 5 2
Vocal fold cyst 2 2
Scar 2 2
Nodules 2 2
Vocal fold paresis 2 2
Superior laryngeal nerve paralysis 2 2
Spasmodic dysphonia 1 2
Normal (vocal fatigue) 2 2
*DVS: diagnostic value of stroboscopy

certified Otolaryngologists. Patients with dysphonia of men, 80 women and four children. The adult patients’ age
non clarified etiology due to difficult indirect laryngosco- ranged from 18 to 84 years (mean: 51.4, SD: 16.9). The
py were excluded from the study since in these cases flex- children were 6 years old (two children), 10 and 11 years
ible laryngoscopy alone often established the diagnosis. old.
Exclusion criteria were a recent endotracheal anaesthesia A detailed medical and voice use history was ob-
and a change of the patients’ voice according to their per- tained by all patients. The patients were first examined
ception since the initial examination. with constant light rigid laryngoscopy by the same exam-
One hundred and fifty consecutive patients with an iner who then performed the stroboscopy (rigid and when
initial diagnosis of a benign lesion (nodules, cyst, polyp), indicated flexible rhinopharyngo-laryngoscope). The lar-
laryngitis, vocal fold oedema, Reinke’s oedema, muscle yngoscopic findings were recorded to the form appearing
tension dysphonia, neurogenic dysphonia, vocal fold at- in Table 1. Stroboscopy included examination during sus-
rophy, spasmodic dysphonia, mutational dysphonia, and tained phonation of the vowels /e/ and /i/ at the patient’s
dysphonic patients with normal laryngoscopy were stud- habitual loundeness and pitch and during loundness and
ied prospectively. Our study population consisted of 66 pitch scales, short phonation followed by inhalation,
326 PRINTZA A

and coughing. Phonation during connected speech, and fered additional information regarding dysphonia. One
singing were evaluated with flexible endoscope strobos- third of the patients examined (51 patients, 34.4%) had
copy. The Maximum Phonation Time (MPT) was mea- no benefit from the stroboscopic examination. One pa-
sured, dysphonia was rated with the use of the GRBAS tient had an early invasive lesion.
scale and the patients were invited to complete the Voice The diagnostic value of stroboscopy differed con-
Handicap Index (VHI)1,8,9. Patients submitted to micro- siderably depending on the pathology (Table 3). It was
laryngoscopy had an operative diagnosis and a pathology greater for the following pathologies: sulcus vocalis, vo-
report to formulate the final diagnosis. The pathologists cal fold cysts, scars, muscle tension dysphonia, vocal fold
were not blind to the operative diagnosis. Patients who atrophy, psychogenic dysphonia and nodules.
followed a conservative treatment were re-evaluated re- In patients with an initial diagnosis of vocal fold nod-
garding response to treatment. They were included to the ules stroboscopy contributed to the characterisation of
study if they had at least one follow-up examination (for nodules based on the presence of uninterrupted mucosal
conditions not expected to change) or a follow-up period wave. Stroboscopy changed the diagnosis in 6 patients
more than three months. The diagnostic value of stro- who were found to have vocal fold oedema, polyp, and
boscopy was rated at a scale of 0 to 3: 0, no diagnostic sulcus vocalis.
contribution; 1, stroboscopy contributed additional diag- The strobocopic diagnoses in patients in whom lar-
nostic information regarding the cause of dysphonia; 2, yngoscopy failed to reveal any pathology appear in Table
stroboscopy changed the initial diagnosis or was instru- 4. Scars of the vocal folds were missed in two patients.
mental in establishing the diagnosis and 3, stroboscopy One had a small scar whereas the other had an extensive
resulted to a change of the therapy offered to the patient. scar involving the entire length of the vocal fold edge,
Stroboscopic examinations were performed with the AT- with absence of the mucosal wave. Three patients had a
MOS Endo-Stroboscope 6 (ATMOS, Germany), a 90° sulcus vocalis confirmed during microlaryngoscopy in
Wolf laryngostroboscope (Wolf, Germany), a 70° Storz two of them.
laryngeal telescope (Storz, Germany), and the ENF-P4
(Olympus, USA) rhinopharyngolaryngoscope. Discussion
Synopsis of key findings
Statistical analysis This study evaluated the clinical value of stroboscopy
Statistical analysis was performed with the SPSS.11.5 in a cohort comprising of every consecutive patient with
for Windows. Descriptive statistics regarding age, sex, a voice disorder examined in a single institution, exclud-
smoking, VHI, MPT of the study population were per- ing cancer. The participants’ recruitment process led to
formed. The diagnostic value of stroboscopy was calcu- the absence of acute laryngeal pathology. This is in ac-
lated for the patients as a group. Comparison of the diag- cordance with clinical practice since in our health system
nostic value of stroboscopy for different pathologies was videostroboscopy is not part of the otolaryngologic ex-
performed with the use of Kruskal – Wallis test. amination in the emergency care.
For one third of the study’s population stroboscopy
Results established the laryngeal pathology responsible for the
A considerable number of patients had more than one voice disorder or changed the initial diagnosis. The
laryngoscopic finding. The diagnostic value of strobos- choice of treatment was changed for 4.7% of the study
copy was evaluated for the main diagnosis and the ad- population. For one third of the participants stroboscopy
ditional findings of stroboscopy. A great proportion of the offered additional information regarding dysphonia. The
study’s population had moderate dysphonia. The phone- clinical value of this additional information depends on
tory measures appear in Table 2. The percentage of smok- many factors, including each patient’s vocal needs and
ers was 25.33% of the participants, whereas the national profession, and the individual treatment outcome expec-
surveys show that one in two adults in Greece is smoking. tations and therefore cannot be easily quantified.
For 39.3% of participants laryngopharyngeal reflux was
identified as a contributing aetiological factor10 (23 had Strengths of the study
a confirmatory pHmonitoring). For 23 patients submit- The present study was prospective. Stroboscopic ex-
ted to microlaryngoscopy pathology results provided the amination was performed to every consecutive patient
final diagnosis. The definitive diagnosis was indentical regardless of the diagnostic adequacy of the indirect lar-
to the stroboscopic diagnosis for all of our patients. The yngoscopic examination. All stroboscopic examinations
follow-up ranged from one to 15 months (mean: 5, SD: were performed by a single trained examiner to overcome
3.7 months). interjudge reliability issues. Follow up was adequate to
For one third of the study’s population stroboscopy confirm the stroboscopic diagnoses on the grounds of
established the diagnosis (43 patients, 28.8%) by intenti- treatment outcomes.
fying the etiology of dysphonia or changing the initial di-
agnosis. For an additional number of patients it changed Methodological issues
the choice of treatment (7 patients, 4.7%). For about one All examinations were performed by the same physi-
third of the cases (48 patients, 32.2%) stroboscopy of- cian, not blinded to the history or the voice of the patient.
 HIPPOKRATIA 2012, 16, 4 327

Although these factors are recognised to induce bias to attempting to draw quantitative conclusions one should
the diagnosis11, they affected both the laryngoscopic and take into account inter-rater reliability.
the stroboscopic examination. The stroboscopic examination was compared to la-
The use of rigid endoscopes for videostroboscopy ryngeal examinations with varying methodology in dif-
alters the natural phonatory mechanisms12-13 but record- ferent studies. In the study by Woo4 it is not clarified how
ed images are superior to fiberoptic recordings13-14.This the laryngoscopy was performed. Sataloff et al3 report on
limitation applies to laryngoscopy and stroboscopy alike. the comparison between laryngeal mirror examination
In this study flexible stroboscopy was performed for the and fiberoptic/telescopic stroboscopic examination. La-
evaluation of the movement of the supraglottal structures, ryngeal telescopic examination with constant light pro-
the study of muscle tension dysphonia and the observa- vides better laryngeal images than mirror laryngoscopy.
tion of the larynx during connected speech and singing. Casiano et al2 compared constant light laryngoscopy with
Most of the studies examining the diagnostic value stroboscopic light examination and report that 90% of the
of stroboscopy were conducted in University ENT De- patients who had a change in the diagnosis or additional
partments by physicians experienced in the evaluation findings, had this change detected by telescopic evalua-
of voice disorders 2-4. Recruitment of patients in tertiary tion alone2.
care hospitals could be a source of selection bias that in- Regarding the diagnostic value of stroboscopy the
creased the measured diagnostic value of stroboscopy, findings of this study are in agreement with the findings
since many dysphonic patients with easy diagnosis are of other studies taking into account the special charac-
treated in smaller hospitals or in the private sector. teristics of each study population2,3,13. In our study the
The stroboscopic diagnosis is compared to indirect diagnostic value of stroboscopy was found to be greater
laryngoscopy diagnosis, as the standard laryngoscopic for certain pathological conditions: sulcus vocalis, vocal
examination for the evaluation of the clinical value of fold cysts, scars, muscle tension dysphonia, vocal fold
stroboscopy4,15. Verification of the diagnosis is based on atrophy with a small gap and nodules. Similar findings
the operative or histologic diagnosis although standard were reported by other researchers3,4,11,13.
histologic diagnosis is also qualitative. The distinction Twenty six out of the 44 patients for whom the diag-
between small polyps and nodules with the optical mi- nostic value of stroboscopy was significant in our study,
croscope and the usual eosin-hematoxylin stain is not had an unremarkable laryngoscopy. This finding under-
straightforward16-20 and it has been shown that the blind lines the unique ability of the stroboscopic examination
histologic diagnoses of benign lesions changed in 25 - to shed light to minimal pathology of the vibrating vocal
30% of the cases when the pathologists obtained addi- folds undetectable with constant light examination. Small
tional information (history, operative diagnoses)16. vocal fold scars are diagnosed with stroboscopic exami-
nation which reveals disturbance of the mucosal wave
Comparisons with other studies propagation and diminished vocal fold vibration4,11,13,21,22.
The diagnostic value of stroboscopy was evaluated in The diagnosis of muscle tension dysphonia is based on
a general voice disordered population because this study the presence of characteristic findings during phonation
intended to relate the findings to issues of health service (vowels and connected speech) and the absence of struc-
provision to the general population. Professional voice tural pathology13, 23-25. Stroboscopy has been proven very
users represented 12% of the participants, comparable to reliable to rule out the presence of small lesions13, 24-26.
the percentage in a paper by Woo4 (10%) whereas Sata- Videostroboscopy is the most reliable method for the
loff reported on a population consisting mainly by profes- detection of sulcus vocalis4,12,13,27,28. Slow motion and still
sional voice users3. The studies by Sataloff 3 and Casiano2 image observation of the vibrating free edge of the vocal
were retrospective and involved selection of patients. Se- folds allows visualization of the characteristic morphol-
lection and exclusion criteria are not clearly stated. Satal- ogy even of a smaller sulcus and observation of the di-
loff reported on 60% of the patients examined and 40% minished amplitude of mucosal wave13,27,28.
of the voice visits during the study period3. Casiano et al Stroboscopy can discriminate different types of small
report2 on all the patients who underwent videostrobosco- lesions (nodules, small polyps, cysts) and point to the
pies over a defined period for whom there was a previous correct treatment without delay4,12,13.This is the pathology
otolaryngologic evaluation at the same institution. The for which stroboscopy was found to be most valuable in
study by Woo was prospective4. the study by Woo et al4. This is very valuable for profes-
In the present study one physician performed and sional voice users who need a prompt and accurate di-
evaluated all the stroboscopic examinations. This meth- agnosis and treatment of dysphonia16,26. For one third of
odology was also followed in the study by Woo4. In our study population vocal fold pathology was accurately
the study by Casiano et al2 the laryngoscopic diagnosis diagnosed laryngoscopically.
was available from the previous ENT examination and
stroboscopy was evaluated by the senior authors. In the Clinical applicability of the study
study by Sataloff et al, it is not clarified who evaluated Stroboscopy is valued for its excellent ability to ex-
the laryngoscopic and the stroboscopic examinations3. amine the structure and the function of glottis during
Videostroboscopy is a subjective examination and when phonation. It provides information which is not available
328 PRINTZA A

with any other diagnostic method13. It provides the po- 10. Printza A, Kyrgidis A, Oikonomidou E, Triaridis S. Assessing
tential to evaluate the larynx during different phonetory laryngopharyngeal reflux symptoms with the Reflux Symptom
Index: validation and prevalence in the Greek population. Oto-
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Conflict of Interest eostroboscopic Parameters in Differentiating True Vocal Fold
There is no conflict of interest. Cysts from Polyps. Laryngoscope. 1996; 106: 19-26.
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