Conversion Disorder is also known as Functional Neurological Symptom Disorder and is characterised by neurological symptoms (weakness, abnormal movements, or nonepileptic seizures for instance) that are incompatible with a neurologic disorder but nevertheless cause distress and impairment. This article mainly focuses on motor and sensory symptoms. It is a subset of Somatic Symptom Disorder.
The goal of the assessment is to identify inconsistences between symptoms and recognised disease.
Compared to patients with "organic" disease, patients with conversion disorder tend to be younger.  Hemiparesis or monoparesis is the most common presentation, but sensory abnormalities such as hemisensory syndrome can also occur. Conversion disorder presentation patients also have more fatigue, sleep problems, pain, memory/concentration problems, gastrointestinal problems, headache, back pain, joint pain, neck pain, and blackouts.
Many cases are said to have la belle indifference in that they appear unusually cheerful despite their symptoms. However in nearly all cases patients say that were trying to appear cheerful so that the examiner didn't think they were mentally ill.
There is some limited evidence of the following examination signs being useful in identifying conversion disorder:
|Highly Reliable Signs||Reliable Signs||Suggestive Signs|
|Giveway weakness||Spinal injuries Centre (SIC) test||Irregular drift (arm stabilisation)|
|Drift without pronation||Sternocleidomastoid test||Non digiti quinti sign|
|Co-contraction||Collapsing weakness||Falls always towards support|
|Splitting the midline||Non-concavity of the palm||Non-economic posture|
|Splitting of vibration sense||Inconsistence of direction||Non-economic posture|
|Hoover's sign||Mingazzini: irregular drift||Sudden knee buckling|
|Non-anatomical sensory loss|
|Bizarre excursion of trunk|
This is a common finding in conversion disorder and is used upon finding hip flexion or hip extension weakness or direct testing. It is based on the crossed extensor reflex.
- Hip flexion weakness: In health patients and in patients with an organic hemiparesis when they are in a supine position and flex their weak hip they will automatically extend their normal hip. This can be felt by placing the hand under the normal heel and feeling downward pressure. If the examiner feels nothing then this suggests conversion disorder. This means that effort is not being transmitted to either leg
- Hip extension weakness: The patient flexes their good leg against resistance while keeping your hand under the heel of the weak leg. If you feel downward pressure that was not there on direct testing this is an inconsistency that is suggestive of conversion disorder.
Hoover's sign can still be positive in patients with organic disease for example if the patient wants to prove to you that they are weak, distress, or difficulty in understanding your instructions. Pain can also affect the sign in several ways.
There has been early research on applying this sign to arm weakness with shoulder abduction and adduction.
Dragging monoplegic gait: Here there is a striking "dragging gait" where one leg is dragged with the knee extended and the hip internally or externally rotated. This is not a common finding.
Co-contraction sign: There is simultaneous contraction of agonist and antagonist muscles. For example during muscle strength testing of the agonist biceps muscles there is also contraction of the antagonist triceps muscle in conversion disorder
Give-way or collapsing weakness: The patient is asked to exert force in a particular direction while the examiner lightly exerts force in the opposite direction. In conversion disorder there is an abrupt decrease in resistance as the limb suddenly gives way. This sign can be falsely positive in chorea, pain, joint problems, and difficulty in understanding instructions.
Drift without pronation: The patient is asked to hold their supinated arms in the air with fingers adducted and eyes closed. In conversion disorder the affected limb by drift downwards but without the accompanying pronation seen in upper motor neuron lesions.
Sternocleidomastoid test: The patient is asked to rotate their head against resistance. In conversion disorder there is difficulty in rotating towards the affected side.
Global or inverted pyramidal pattern of weakness: for example extensors being weaker than flexors rather than the organic expected opposite finding.
Midline splitting: The cutaneous branches of the intercostal nerves overlap and so any midline splitting in most organic diseases should be 1 to 2cm from the midline. Exact midline splitting occurs in thalamic disease and conversion disorder.
Midline splitting of vibration: In conversion disorder there may be splitting of altered vibration sense over the forehead and sternum. As these are single bones splitting should not occur in organic disease.
Spinal Injuries Centre (SIC) Test: The patient is in a supine position while the examiner passively lifts the patient's knees to a flexed position with the feet flat on the bed. The examiner releases the patient's knees. If the patient is able to maintain the flexed position then this is a positive test for conversion disorder. In severe paralysis the patient should not be able to maintain their knees in the flexed position with the paretic limb spontaneously dropping into extension.
Tremor entrainment test: The patient is placed in a position where the tremor is at its maximum, which is usually with the arms out in front. Move the least tremoring or non-tremoring limb slightly away from the other limb and ask the patient to focus on it. The patient is asked to tap another limb at a different frequency to the tremor, such as tapping with their thumb and forefinger to a rhythm set by the examiner. The rhythm should vary making it faster and slow and the patient should be encouraged to follow the examiner.
The sign is positive with a change in tremor with distraction of attention. In those with conversion disorder there are three signs that indicate a positive test.
- A shift in the tremor frequency. There are pauses or other disruptions to the tremor when tapping at a different frequency with the other limb
- Poor task performance. There is a paradoxical and inexplicable difficulty in tapping at a difference frequency to the tremor with the unaffected limb.
- Pure entrainment. The tremor frequency shifts to match the frequency of the tapping. This is not common.
Waddel's signs: These signs have been described in patients with back pain and conversion disorder. They are not proof of malingering or exaggeration but may indicate that reports of pain are increased when the doctor and patient are paying attention to it.
- Straight leg raising while lying and sitting. If a patient can sit comfortably on an examination table with their legs stretched out at 90 degrees to their body, any pain induced by straight leg raising in the supine position cannot be due to true sciatic nerve pain
- Simulated rotation. The patient is asked to stand with their feet flat on the floor and rotate their trunk with their arms stabilised at their sides. This movement occurs at the knees and so the back shouldn't be painful.
- Localised tenderness: There may be exquisite tenderness to light palpation
- Axial loading: Axial pressure on the top of the head shouldn't cause significant back pain.
The following subtypes have been observed
- Nonepileptic seizures
- Weakness and paralysis
- Abnormal movement
- Speech symptoms
- Globus sensation
- Sensory symptoms
- Visual symptoms
- Cognitive symptoms
Investigations are usually necessary. This is because clinical diagnosis cannot exclude a comorbid organic disorder. It is best to do all the necessary tests at the same time rather than sequentially in order to not delay the diagnosis. The patient should be warned that investigations are likely to be normal or only show age related change.
In the DSM V criteria conversion disorder is based on finding incompatibility between the symptoms and recognised medical conditions. It uses both negative and positive signs.
- A: One or more symptoms of altered voluntary motor or sensory function
- B: Clinical findings provide evidence of incompatibility between the symptom and recognised neurological or medical conditions
- C: The symptom or deficit is not better explained by another medical or mental disorder
- D: The symptom or deficit causes clinically significant distress or impairment in social, occupation, or other important areas of functioning or warrants medical attention.
Misdiagnosis is uncommon. In one study of 1144 patients in Scotland there was misdiagnosis of only 4 patients at 18 months.
The prognosis is often poor. In most patients functional motor symptoms persist. Improvement is seen in one third. Sensory symptoms have a better prognosis than weakness. Fixed dystonia has the worst prognosis.
Good prognostic factors are a willingness to accept the potential reversibility of symptoms, good interaction with the doctor, short duration of symptoms, and lack of other physical symptoms.
Poor prognostic factors are strong beliefs in the lack of reversibility, anger at the diagnosis of conversion disorder, delayed diagnosis, multiple other physical symptoms, concurrent organic disease, personality disorder, older age, sexual abuse, financial interest in maintaining sickness, and litigation. These factors only explain a limited amount of variance in prognosis.
A successful explanation leaves the patient feeling like they have "gotten to the bottom" of their problem, while feeling that they have something genuine, but potentially reversible with treatment. In those who do not improve there is value in accepting the diagnosis in order to stop doctor shopping.
Showing patients their positive signs such as the Hoover sign for weakness or the tremor entrainment test for tremor is helpful. The patient should be told that the signs indicate that their problem is potentially reversible.
The terminology used is important. The term psychogenic or conversion disorder may make the patient feel like the doctor thinks they are crazy. Functional is a more acceptable term. The term functional describes a mechanism and leaves the aetiology more open. This is compatible with the biopsychosocial model.
The textbook neurology in clinical practice provide the following ingredients for successful explanation for functional symptoms/disorders.
|Explain what they do have.||“You have a functional movement disorder.”
“You have dissociative attacks.”
|Emphasize the mechanism of the symptoms rather than the cause.||Weakness: “Your nervous system is not damaged, but it is not functioning properly.”
Attacks: “You are going into a trancelike state, a bit like someone being hypnotized.”
|Explain how you made the diagnosis.||Show the patient their Hoover sign, tremor entrainment, or dissociative attack video, explaining why it is typical of the diagnosis you are making|
|Indicate that you believe them.||“I do not think you are imagining/making up your symptoms/going crazy.”|
|Emphasize that it is common.||“I see lots of patients with similar problems.”|
|Emphasize reversibility.||“Because there is no damage, you have the potential to get better.”|
|Emphasize that self-help is a key part of getting better.||“This is not your fault, but there are things you can do to help it get better.”|
|Metaphors may be useful.||“The hardware is alright, but there’s a software problem.”
“It’s like a car/piano that’s out of tune.”
|Explain what they don’t have and why.||“You do not have multiple sclerosis (epilepsy, etc.).”|
|Introduce the role of depression/anxiety.||“If you have been feeling low/worried, that will tend to make the symptoms even worse” (often easier to achieve on a second visit).|
|Use written information.||Send the patient their clinic letter; give them a website address (e.g., https://www.neurosymptoms.org, https://www.nonepilepticattacks.info).|
|Stop the antiepileptic drug in dissociative
|If you have diagnosed dissociative attacks and not epilepsy, stop the anticonvulsant; leaving the patient on the drug will hamper recovery|
|Suggest antidepressants when appropriate.||“So-called antidepressants often help these symptoms even in patients who are not feeling depressed; they are not addictive.”|
|Make the psychiatric referral when
|“I don’t think you’re mentally ill, but Dr X has a lot of experience and interest in helping people like you to manage and overcome these kinds of symptoms. Are you willing to overcome any misgivings about his/her specialty to try to get better?”|
|Involve the family/friends.||Explain it all to them as well.|
There is sustained benefit even for patients with chronic symptoms. There are specific features in the physiotherapy approach. For example rather than paying attention to the weak limb, distraction techniques are used to allow better movement. Graded exercise can be helpful. Mental imagery and mirror therapy can also be used.
There is evidence of benefit for cognitive behavioural therapy.
Tricyclic antidepressants are favoured, and outcomes are not affected by the presence or absence of depression. Tricyclics can be especially helpful in pain and insomnia. However patients may be especially sensitive to drug side effects and so they should be started at a low dose and increased slowly.
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