Lec 5 Flashcards
You need this before you can attribute a headache to TMD.
Primary TMD diagnosis
In a normal disc position, in the sagittal plane, relative to the superior aspect of the condyle, the border between the low signal of the disc and the high signal of the retrodiscal tissue is located between which clock positions?
11:30 and 12:30
For a normal disc, in the sagittal plane, the intermediate zone is located between what?
The anterior-superior aspect of the condyle and the posterior-inferior aspect of the articular eminence.
Describe the position of the posterior band on the condyle when the mouth is closed.
Should be POSTERIOR to the 11:30 position.
Should NOT be anterior to the 11:30 position.
Location of the intermediate zone in disc displacement.
ANTERIOR to the superior part of the condyle.
What does the posterior band look like on an MRI?
Where the white and gray parts meet at the line.
Posterior band is WHITE on an MRI.
Diagnose the disc displacement:
In the closed mouth position, the disc is in an anterior position relative to the condylar head and the disc reduces upon opening of the mouth.
Medial and lateral displacement of the disc may also be present.
Clicking, popping, or snapping noises may occur with disc reduction.
A hx of prior locking in the closed mouth position coupled with interference in mastication precludes this dx.
Disc displacement with reduction.
Hx in disc displacement with reduction.
Hx of joint sounds
Dx:
1 click on opening, or 1 click on closing.
1 click in opening; 1 in closing, +1 click in lateral protrusive movements.
2 vertical clicks, or 1 vertical and 1 horizontal click
Disc displacement with reduction.
Dx:
In the MRI:
1) In the maximum intercuspal position, the posterior band of the disc is anterior to the 11:30 position and the intermediate zone of the disc is anterior to the condylar head; AND
2) On full opening, the intermediate zone of the disc is located between the condylar head and the articular eminence.
Disc displacement with reduction.
Only this can diagnose a lateral or medially displaced disc.
MRI
Dx:
In the closed mouth position, the disc is in an anterior position relative to the condylar head, and the disc intermittently reduces with opening of the mouth.
When the disc does not reduce with opening of the mouth, intermittent limited mandibular opening occurs.
When limited opening occurs, a maneuver may be needed to unlock the TMJ.
Medial and lateral displacement of the disc may also be present.
Clicking, popping, or snapping noises may occur with disc reduction.
Disc displacement with reduction with intermittent locking.
When does a jaw lock?
When the disc does NOT reduce when you open the mouth.
Hx for disc displacement with reduction with intermittent locking.
Jaw locks with limited opening, even for a moment, and then unlocks.
If there’s no sounds, then there’s no what?
Reduction
Limited opening means maximum assisted opening is less than how many mm?
40
Closed lock
When you can’t open your mouth all the way.
Open lock
When you can’t close your mouth all the way.
Dx:
History of:
1) Locked jaw so that the mouth cannot open all the way AND
2) Limitation in jaw opening severe enough to limit jaw opening and interfere with ability to eat.
Disc displacement WITHOUT reduction with limited opening.
T/F:
You know there’s NO reduction when the posterior band is anterior to the 11:30 position when the mouth is OPEN.
TRUE
Dx:
In the closed mouth position, the disc is in an anterior position relative to the condylar head and the disc does not reduce with opening of the mouth. Medial and lateral displacement of the disc may also be present. This disorder is NOT associated with current limited opening.
Exam:
Maximum assisted opening movement including vertical incisal overlap is greater than or equal to 40 mm.
Disc displacement without reduction without limited opening
Can you have TMJ noise (clicking during opening) in disc displacement without reduction?
Yes
Clicks during what movement are needed for reduction?
During opening and closing, or one opening/closing and one horizontal movement.
For degenerative joint disease, we use this machine.
CT
Useful for assessing osseous deformities, but CANNOT produce accurate images of the articular disc.
CT
Dx:
1) Normal relative size of the condylar head.
2) No subcortical sclerosis or articular surface flattening.
3) No deformation due to subcortical cyst, surface erosion, osteophyte, or generalized sclerosis.
Normal Joint/condyle
The condyle or eminence have bone changes in this.
Degenerative Joint Disease
Continuous crunching sound.
Crepitus
Hx for what disease?
1) In the last 30 days, any TMJ noises with jaw movement or function. OR
2) Pt reports of any noise during the exam.
Degenerative Joint Disease
Exam for what disease?
Crepitus detected with palpation during any movement.
Degenerative Joint Disease
These findings do NOT mean that you have Degenerative Joint Disease
Flattening or cortical sclerosis
These imaging findings indicate you have Degenerative Joint Disease.
- Subchondral cysts
- Erosion
- Generalized sclerosis
- Osteophytes
What is loss of cortical bone, like someone is chewing it?
Erosion
What does generalized sclerosis look like on a CT scan?
The condyle is completely white.
When the jaw is locked open (can’t close), and the patient has to self-maneuver it to reduce the dislocation.
Subluxation.
When the patient has an open lock, and needs a doctor to put it back into position.
Luxation
Luxation and Subluxation are AKA
Open lock
Dx:
In the open mouth position, the disc-condyle complex is positioned anterior to the articular eminence and is unable to return to a normal closed mouth position without a manipulative maneuver.
When the patient can reduce the dislocation himself/herself, this is called what?
Subluxation
What does CT imaging for subluxation show?
The condyle is positioned anterior to the articular eminence with the patient unable to close his/her mouth.
Most frequent cause of TMJ ankylosis is this?
Macrotrauma
These are characterized by restricted mandibular movement with deflection to the affected side on opening that may result as a long-term sequela of trauma, including mandibular fracture.
Intra-articular fibrous adhesions and ankyloses.
The formation of a bony mass that results in fusion of the joint compartments.
Osseous ankylosis
Fibrous adhesions of the TMJ that cause hypomobility occur in which compartment?
Superior
Marked deflection to the affected side is seen in what kind of disorders?
Hypomobility
Most common ankylosis
Fibrous
This type of ankylosis has no radiographic finding other than the absence of ipsilateral condylar translation on opening.
Fibrous ankylosis
Has radiographic evidence of bone proliferation with deflection to the affected side and limited laterotrusion to the contralateral side.
Osseous ankylosis
Must have the following to diagnose what kind of ankylosis?
1) Limited range of motion on opening.
2) Marked deflection to the affected side.
3) Markedly limited laterotrusion to the contralateral side.
4) No radiographic evidence.
5) Decreased to complete lack of ipsilateral condylar translation on opening.
6) A disc space between the ipsilateral condyle and the eminence.
Fibrous Anklyosis
Disc space difference btw fibrous and osseous ankylosis.
No disc space in osseous ankylosis bc it’s replaced with bone.
In this ankylosis, imaging must show bone proliferation with obliteration of part or all of the joint space.
Osseous
Increase in the normal number of cells (non-neoplastic)
Hyperplasia
Incomplete or underdevelopment of the cranial bones or mandible.
Hypoplasia
Unilateral absence of the condyle and incomplete development of the articular fossa and eminence, causing facial asymmetries.
Aplasia
This causes an open bite when in the TMJ.
Rheumatoid Arthritis
This occurs when the condyles shorten, and the elevator muscles pivot the joint.
Open bite
What color is the posterior band?
WHITE
