Khalid H Al Malki, MD, PhDConsultant, Associate Professor

Phoniatrics (Voice, Communication and Swallowing Disorders)

Head, Communication and Swallowing Disorders Unit (CSDU)

Deputy chairman, ENT Department

King Abdulaziz University Hospital

King Saud University, Riyadh, Saudi Arabia.

Head, Communication and Swallowing Division (CSDD)

ORL/HNS Department

Riyadh Military Hospital, Riyadh, Saudi Arabia

http://faculty.ksu.edu.sa/kmalky/default.aspx

LaryngealStroboscopy

Khalid H Al Malki, MD, PhD

To explore * Anatomy,

* Physiology,* Assessment,

* Management,* Prognosis

* Referralsof Voice Disorders.

Lecture Objectives:

Khalid H Al Malki, MD, PhD

Stroboscopy

Khalid H Al Malki, MD, PhD

Definition:

A stroboscope, also known as a strobe, is aninstrument used to make a moving object appears tobe slow-moving or stationary.

The principle is used for the study of rotating,oscillating, or vibrating objects.

Khalid H Al Malki, MD, PhD

Definition (cont):

In electronic versions, a lamp is capable of emittingbrief and rapid flashes of light.

The frequency of the flash is adjusted so that it is aequal to, below, or above the object's vibration speed.

The object will be seen to be either stationary ormoving backward or forward, depending on the flashfrequency.

Khalid H Al Malki, MD, PhD

History:

Joseph Plateau of Belgium is generallycredited with the invention of thestroboscope in 1832, when he used adisc with radial slits which he turnedwhile viewing images on a separaterotating wheel.

Plateau called his device thePhenakistoscope.

Khalid H Al Malki, MD, PhD

Phenakistoscope means deceptive view.

Khalid H Al Malki, MD, PhD

Khalid H Al Malki, MD, PhD

History (cont):

There was a simultaneous andindependent invention of the device bythe Austrian Simon von Stampfer,which he named the "Stroboscope",and it is his term which is used today.

The etymology is from the Greek wordsstrobo(s), meaning "whirling" andscope meaning "to look at".

Khalid H Al Malki, MD, PhD

In 1895, a German internist named Max JosephOertel used a stroboscopic light source with alaryngeal mirror to investigate voice production indifferent registers.

This allowed him to view the vibrating vocal foldsin arrested or apparent slow motion.

History (cont):

Khalid H Al Malki, MD, PhD

History (cont):

The electronic strobe light stroboscope was invented in 1931, when Harold Eugene Edgerton employed a flashing lamp to study machine parts in motion.

Edgerton, later, used very short flashes of light as a means of producing still photographs of fast-moving objects, such as a dropping drop.

Khalid H Al Malki, MD, PhD

Laryngostroboscopy

Khalid H Al Malki, MD, PhD

Talbot's law:

Images presented to the retina for less than 0.2 seconds each(more than five images/second) will persist and are fusedtogether by the ocular cortex to produce apparent motion.

True vocal folds vibrate at rates of 75 to 1000 cycles/second,so the vibratory patterns cannot be visualized withoutassistance.

Khalid H Al Malki, MD, PhD

NEW VIEW:

Two visual perception phenomena play roles in laryngealstroboscopy:

(a) Perception of a flicker-free presentation of the movingobject (presentation frequency should be above 50Hz).

(b) Perception of apparent motion from sampled imageswhen no real motion exists (presentation frequencyshould be above 17 Hz).

Khalid H Al Malki, MD, PhD

Strob Illusion Strob Machine

Khalid H Al Malki, MD, PhD

Laryngeal stroboscopy is more than laryngealendoscopy.

Strob light

Laryngeal stroboscopy is widely agreed on tobe the single most important clinical voiceassessment tool.

Khalid H Al Malki, MD, PhD

Importance of Laryngostroboscopy:

Allows clinician to see vibratory patterns of true vocal folds.

Enhances clinicians diagnosis ability.

Early and accurate detection of glottal/laryngeal pathologies.

Documents glottal/laryngeal condition to computer.

Allows pre-/post-intervention follow-up of vocal folds.

Can be used in patient education and biofeedback.

Khalid H Al Malki, MD, PhD

Importance of Laryngostroboscopy (cont.):

Videostroboscopy contributed significant diagnostic information in27.2% of the cases (versus non-stroboscopic means).

It was instrumental in changing the diagnosis in 10% of the cases.

Case no. 4: original diagnosis was recurrent laryngeal cancer;changed to excessive mucous.

Diagnostic Value of Stroboscopic Examination in Hoarse Patients, Woo, Peak, et.al.; 1991: Journal ofVoice, Vol. 5; No. 3

Khalid H Al Malki, MD, PhD

Importance of Laryngostroboscopy (cont.):

Diagnoses were noted before and after employing use ofvideostroboscopy in 377 patients.

Results: 29% of original diagnoses: had additional diagnosis added. 18% of original diagnoses: were incorrect. 47% of original diagnoses: were modified.

Strobovideolaryngoscopy: Results and Clinical Value; Sataloff, et.al.; Annals of Oto, Rhino,Laryngo, September 1991

Khalid H Al Malki, MD, PhD

Khalid H Al Malki, MD, PhD

Khalid H Al Malki, MD, PhD

Khalid H Al Malki, MD, PhD

Laryngeal endoscopic examination:

1. Movement Gross true vocal fold mobility.

2. Mucosa.

3. Mass or lesion.

4. Mucosal wave. and other stroboscopic findings.

5. Muscle Supraglottic hyperfunction.

6. More RFS.

Khalid H Al Malki, MD, PhD

Stroboscopic examination:

1- Glottic closure: complete, incomplete (shape).

2- Glottic gap: site, size.

3- Mucosal wave: great, normal, small, absent. **

4- Amplitude: great, normal, small, zero. **

5- Symmetry: in phase, in amplitude. **

6- Periodicity: periodic, aperiodic. **

7- Phase closure: open phase predominate, close phase predominate. **

8- Stroboscopic fixation. **

Khalid H Al Malki, MD, PhD

Limitations of Laryngostroboscopy:

1. Severe dysphonia, or aphonia.

2. Supraglottic hyperfunction (constriction).

3. Two-dimensional image only.

4. Patients cooperation is needed.

5. Illusion of continuous motion.

Khalid H Al Malki, MD, PhD

Other Imaging Modalities

Khalid H Al Malki, MD, PhD

:Videolaryngokymography (VKG)

VKG uses a modified video camera to gather 8000 lines/second of a single video line.

The resultant image is really a series of image lines (x-axis) over time on the y-axis.

Khalid H Al Malki, MD, PhD

Khalid H Al Malki, MD, PhD

VideolaryngokymogramKhalid H Al Malki, MD, PhD

:Speed Video (HSV)-High The main limitation of stroboscopy is that it assembles(samples) images from many cycles to represent intra-cycle behavior.

High-Speed Video (HSV) uses very high- speed (e.g.,~2000 frames/sec.) video cameras to record and view theintra-cycle laryngeal behavior.

Khalid H Al Malki, MD, PhD

Khalid H Al Malki, MD, PhD

:Speed Video-HighLimitations of

1. Lots of light is needed.

2. No sound recording.

3. Endoscope becomes hot.

4. High cost.

Khalid H Al Malki, MD, PhD

Although still as research tools, currentlyhigh-speed video and videokymographyshould be considered as adjunct methodsto laryngostroboscopy.

Khalid H Al Malki, MD, PhD

Thank You

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