AN APPROACH TO CERVICAL DYSTONIA

Con Yiannikas

Evaluation of Cervical Dystonia in terms of:

• Postural deviation in the axial plane (torticollis)

• Coronal plane (laterocollis)

CLASSIFICATION OF CERVICAL DYSTONIA

• Saggital plane (anterocollis and retrocollis)

• Most patients with cervical dystonia have postural deviation in at least two of these planes.

• In addition, the presence of shoulder elevation and of saggital and lateral shift are important elements to note.

CLASSIFICATION OF CERVICAL DYSTONIA

FREQUENCY OF ABORMAL HEAD POSTURES

CAPUT-COLLIS CONCEPT

TORTICAPUT 

C3

C7

Head rotated  via C1-2  {Atlanto-axial joint}

C3-7 vertebral column column no movement

TORTICOLLIS

C3-6 rotate with C1-2 and head

C7

C3

The larynx is not above the sternum

AXIAL ROTATION-TORTI

ROTATION OF HEAD

• Attaching to skull
   
• Unilateral contraction

Anterolateral muscles contralateral rotation 

Posteromedial contralateral rotation

Posterolateral muscles ipsilateral rotation

Splenius capitus

Longissimus capitus

Splenius cervicus

Trapezius

SCM

• Semispinalis capitis
• Spinalis capitis

TORTICAPUT

Muscles attaching to skull –

• Trapezius
• Sternomastoid

        Contralateral rotation

• Obliquis capitis inferior

• Semispinalis capitis
• Spinalis capitis

        Ipsilateral rotation

• Splenius capitis
• Splenius cervicis
• Longissimus capitis

Lateral

Midline

TORTICOLLIS

Muscles attached to spine

        Contralateral rotation

• Semispinalis cervicis

• Scalenus anterior

        Ipsilateral rotation

• Longissimus cervicis

RETROCAPUT

RETROCOLLIS

MOTION IN THE SAGITTAL PLANE-RETRO

EXTENSION

Posterior and posterolateral muscles acting together

RETROCAPUT- ATTACH TO SKULL

• 13 degrees

Attach to skull

• Trapezius
• Sternomastoid
• Splenius capitus, cervicus
• Semispinalis/Spinalis capitus
• Longissimus capitus
• Obliques capitus inferior

Range of motion

capitus

cervicus

RETROCOLLIS- ATTACH TO NECK

Midline -attach to spine

• Semispinalis cervicis
• Longissimus cervicis

Range of Motion

• 66 degrees

ANTEROCOLLIS

ANTEROCAPUT

MOTION IN SAGITTAL PLANE- ANTERO

FLEXION

Anterior muscles acting together

ANTERO- CAPUT

• Longus Capitis
• Platysma
• Digastric/submental

Insert base of skull or jaw

ANTEROCOLLIS

• Scalenus medius and anterior
• Longus Colli

Insert Spine

• Extends head and flexes spine

SCM

LATEROCOLLIS

Larynx shifted relative to sternum

LATEROCAPUT

MOVEMENT IN THE CORONAL PLANE

LATERAL FLEXION

LATEROCAPUT

Muscles that insert into skull (mastoid/ occiput)

• Trapezius
• Sternomastoid
• Splenius capitus/cervicus
• Levator scapulae
• Longissimus capitus

Range of movement

• 8 degrees

LATEROCOLLIS

Long muscles transversing spine

• Levator scapulae
• Scalenus Anterior/medius
• Semispinalis cervicis
• Longissimus cervicis

Biomechanical advantage

• Range - 37 degrees

LATERAL SHIFT

Secondary to lateral flexion of the spine and flexion of the head in the opposite direction.

LATERAL SHIFT

LATERAL SHIFT

LATERAL SHIFT

SAGITTAL SHIFT- PROTRACTION

Due to a combination of extension of head and flexion of neck. 
Often due to bilateral tonic contraction of Sternomastoid

SAGITTAL SHIFT- RETRACTION

Due to a combination of neck extension and head flexion. 
Produces “double chin” look. 

LATERAL AND SAGITTAL SHIFT

CLINICAL ASSESSMENT OF CERVICAL DYSTONIA 

• Voluntary movement is affected by co-contracting muscle pairs- it is important to assess range of individual neck movements but also the effort required and the localisation of pain associated with the movement.

Line from Sternum to larynx 

• Sensory Tricks/ Triggers

• Determination if neck or head or both are involved, description of abnormal posture and determination of muscles to be targeted.

• Determination of axis

GENERAL PRINCIPLES- CO-CONTRACTION 

Voluntary movement is affected by co-contracting muscle pairs. It is important to assess range of individual neck movements but also the effort required and the localisation of pain associated with the movement.

In this patient there is co-contraction of ipsilateral Trapezius and Levator scapulae on the left, restricting rotation to the left and causing local pain​

ASSESS DYSTONIA IN VARIOUS POSTURES 

Assessment of head position sitting, walking and laying down as this may change .

SENSORY TRICKS OR TRIGGERS​

ROLE OF EMG 

• Accuracy of Muscle Localization
   
• Planning of muscles to inject - determination of active muscles
   
• Localization of endplates
   
• Less problems with diffusion

ACCURACY OF MUSCLE LOCALIZATION

• Muscles deep
• Not easily identified by surface landmarks
• Not palpable on examination

ACCURACY OF LOCALIZATION - SCALENES

ACCURACY OF LOCALIZATION LEVATOR SCAPULAE 

LOCALIZATION OF MUSCLES IN DEEPER LAYERS

Layer 1

Layer 2

Layer 3

Splenius Capitis

Semispinalis Capitis

Longissimus Capitus

Semispinalis Cervicis

ACCURACY OF LOCALIZATION – DEEPER LAYERS

INJECTION SITES

BIOMECHANICS OF HEAD MOTION

MOTION OF THE HEAD ON NECK

LATERAL TILT OCCURS BETWEEN C0-C1 

ROTATION AT C1-2, FLEXION EXTENSION MAINLY AT C0-1

BIOMECHANICS OF NECK MOVEMENT

RANGE OF MOTION

BIOMECHANICS OF NECK MOTION

• Most lateral flexion and flexion/extension occur serially from C2 through C7.
   
•  Long muscles spanning these segments have great advantage in lateral flexion and in flexion/extension.
   
• The majority of head rotation occurs at the atlanto-axial joint, so that muscles that act across this joint (e.g. obliquus capitis inferior, splenius capitis, SCM) have advantage in producing turning movements
   
• Rotation at C1-2 requires some extension and lateral tilt

UNIQUE ACTION OF STERNOMASTOID

Extends the head and flexes neck when longus colli relaxed

Flexes head and cervical spine if deep 
flexors [longus colli] are contracted

F UNIQUE ACTION LEVATOR SCAPULAE

Insertion

Medial edge of the scapula, between the superior angle and the root of the spine.

Origin

First to the fourth cervical vertebrae

LEVATOR SCAPULAE

Action

Acts as a checkrein for the bent head

LEVATOR SCAPULAE AND NECK MOTION

Left Lateral Flexion

Right Rotation

Extension

Left UTrapezius, SCapitus and Levator Scapulae

Left UTrapezius,  Right SCapitus, Levator Scapulae

Bilateral U Trapezius Scapitus, Levator Scapulae

LEVATOR SCAPULAE IN DROPPED NECK