AHP Flashcards
Normal head posture
When the body is erect and facing forwards. The median plane of the head is continuous with the median plane of the body
AHP aka compensatory head posture causes
Ocular cause or Non ocular
Ocular cause
Used to regain BSV and alleviate diplopia
The abnormal position of the head may consist of
Face turn to R or L, Chin elevation or depression, Head tilt to R or L shoulder
Torticollis is a combination of
Tilt and turn
Non ocular causes of AHP long
Congenital- Contracture of sternocleidomastoid muscle in neck
Head tilt to affected side
Head turn to unaffected side
May adopt chin elevation (head up)
Non ocular causes of AHP acq
Acquired- Deafness - unilateral/ asymmetrical - Head turn to more affected side
Shyness- Often chin depression (Head down) and variable
Mental retardation- Often variable AHP
Habit
Neurological – brain tumour
Arthritis / rheumatism
Disorders/ injuries of spine
Do non ocular AHP patients have ocular problems
Generally patients with non-ocular AHP do not c/o ocular problems, but if referred, should undergo careful motility examination to rule out co-existing motility disorders
Ocular causes of AHP
Obtain/ maintain BSV- Incomitant strabismus, A & V patterns
Separate diplopic images further- Insuperable diplopia
Gain foveal fixation- Infantile esotropia, Gross limitation preventing foveal fixation in PP
Optimise VA- Refractive errors- incorrect astigmatism , Nystagmus- have null point where nystagmus dampens and this improves VA
Further ocular causes of AHP
DVD- Head tilt towards fixing eye appears to ↓ DVD
Centralise field of vision- Bilateral ptosis- chin elevation or head up
Gaze palsies- seen in stroke patients cant move eyes to r/l
Homonymous hemianopia- cant see to one side
Avoid pain- Graves Ophthalmopathy, Blow-out #
Value of AHP
Aids in diagnosis of affected EOM in palsies
Aids in differential diagnosis of longstanding versus recently acquired palsies
Degree of AHP < in longstanding palsies
Patient less aware of AHP in longstanding
Presence of pre-existing BSV
Patients with a marked AHP such as a head tilt due to SO plasy, you may consider under-correction as patient is unlikely to resume normal head posture
Longstanding- AHP not noticed, size is smaller
Acquired- AHP noticed, size is greater
SO palsy- extended v fusion range
Assessment of AHP
Ensure patient sitting / standing straight
Observe patient on same level, directly in front
Note any facial asymmetry
Assess if one ear more visible than other
Check eyes are level
Further assessment of AHP
Observe chin position from side
Straighten head and allow patient to resume “normal” position
Observe AHP for 1/3m, 6m, when performing visual task
Old photos may identify duration of AHP
AHP differs in positions in 6th nerve palsy- record this
Ask patient if aware of AHP
Features of CONG AHP
CONG non ocular
Straightening head - difficult/ impossible
Ocular symptoms- asymptomatic
Aware of AHP- maybe
Presence of BSV- C +S HP
CT NAD
OM Full
HESS normal
Congential AHP cause
contracture of sternocleidomastoid muscle in neck
Features of ocular AHP
Straightening head - easy
Ocular symptoms- may be symptomatic
Aware of AHP- often unaware esp if longstanding and if neck ache its acquires
BSV- yes c AHP, no s AHP can have diplopia and suppress
CT- presence of strabismus. nystagmus
OM- muscle imbalance
HESS- muscle imbalance
Ocular AHP cause
Relived diplopia. neurogenic palsy, stroke
How to confirm congenital non ocular AHP
Occlusion of one eye- no change to AHP
Uniocular VA testing- no change to AHP
Medical- reasons for adopting AHP include deafness
How to tell if ocular AHP
Occlusion of one eye- head straightening on occlusion of paretic eye
Uniocular VA testing- may change to improve VA If presence of nystagmus
Medical- may c/o illness relevant to muscle imbalance
Recording AHP
Define- Small, moderate, marked, r/l
Variable or alternating
Distance(s) AHP noted
Present with and without optical correction
Management of AHP - asymptomatic and small
AHP can relieve diplopia and pain and requires no active treatment
Management of AHP- small/ moderate
and can be relieved using prisms, occlusion, BT and surgery- pt can develop neck muscle contraction
Management of AHP- symptomatic and marked
Marked surgery is indicated. This is especially in neurogenic AND mechanical palsies, nystagmus, young children- prevent secondary contractural neck changes. Affect amount of surgery.
Consider under-correct if longstanding
To know
To be able to work out why a patient adopts a AHP you need to know the primary, secondary & tertiary actions of all the EOM’s
Remind RADSIN, rectus muscles ad-duct, oblique ab-duct
SO palsy hypertropia and esotropia
Reasons for head turn
Move eyes away from field of action of paresed muscle
Move eyes to a position where deviation is least
Enable eye to fixate centrally – gross limitation
Permit the use of the nose as an occluder
Utilisation of VOR-
Head turn L eyes move R
Paralytic strabismus:
Head turned in direction of paresed muscle
Examples of HEAD TURN TO PARESED MUSCLE
RLR palsy- head turn right
LSR palsy- head turn left
Right Duane’s type 1/B- head turn right
Chin elevation and depression purpose
Move eyes away from field of action of paresed muscle
Utilise physiological V pattern
For comfort – mechanical
Head up- chin elevation
Eyes relatively depressed
Relative convergent position of eyes
Head down- chin depression
Eyes relatively elevated
Relative divergent position of eyes
RIR palsy head posture
head down and right- diplopia worse on dextrodepression
Graves opthalmopathy with -4 on elevation both eyes
Head up
Left browns
Head up
When the head is straight vertical meridians of eyes are
parallel
When the head is tilted RIGHT
RE intorts due to RSO & RSR contracts and LE extorts due to LIO & LIR contracts
When the head is tilted LEFT
LE intorts due to LSO & LSR contracts and RE extorts due to RIO & RIR contracts
If LE is extorted in PP , a head tilt to the RIGHT causes
RE intort = vertical meridians are parallel
- Used to overcome torsion/ torsional diplopia
Head tilt causes vertical movement e.g. L tilt
LE sl depressed & RE sl elevated
LE moves up sl & RE moves down sl to neutralise
Head tilt ALWAYS TO…
hypotropic eye- lower eye
Superior muscles SR + SO
tilt and turn SAME WAY
Inferior muscles IR + IO
tilt and turn OPPOSITE WAY
Left blow out c no pain on elevation…
head up
LSO palsy
Head tilt right, head turn right, head down
Dextrodepression, diplopia worse to right
Right eye is lower so tilt to right
Head down so eyes are elevated
Left medial wall with MR muscle entrapment
Left turn
LIR palsy
R head tilt, , head turn left, head down
Laevodepression is affected R eye HoT so turn R
Diolopia worse down do move head down to elevate eye
CPEO with bilateral ptosis
Head up
Measuring had posture in clinic
Often an estimate – slight, moderate, marked
Photographs to see if longstanding
Goniometer used mainly in cong non ocular
Cervical range of motion (CROM) instrument
esigned to assess the range of motion in the cervical spine
CROM typically used for research- can use compass app iphone
Use of technology to measure head posture
Quantitave measure
The Cambridge Face tracker
Phone compass function
May be possible to use but require further research
The Cambridge Face Tracker uses neural networks (constrained local neural fields) to recognize facial features in video.
It allows useful quantification of head posture in real time or from precaptured video. Its performance is similar to the CROM device
Summary
Head turn: towards field of action of paresed muscle
Head tilt: towards side of hypotropic eye
Head up (chin elevation ): moves eyes away from field of action of paresed muscles (SR & IO) bilateral ptosis or pain
Head down (Chin depression): moves eyes away from field of action of paresed muscles (SO & IR)
