Introduction

Many believe that the diagnosis of functional, and for that read non-organic or psychological, disease should be a diagnosis of last resort. Those advocating this approach adopt the view that one should never have functional illness as the number one diagnosis. They believe one should only entertain the possibility after all other potential diagnoses have been excluded. The problem with this concept is that it has the capacity to encourage ‘sick’ behaviour. It reinforces that there is something seriously wrong.

The need for an exhaustive list of investigations before broaching the topic of psychological illness suggests that the true diagnosis is beyond the doctor’s capacity to discern. It suggests that the label of ‘functional illness’ is a euphemism for medical ignorance or incompetence. This may be more worrying to the anxious patient than would be an early identification of the probable diagnosis of psychological illness.

It does not mean that the provisional diagnosis of non-organic disease should exclude investigation for alternative differential diagnoses. While a provisional diagnosis is the most likely answer, it is not the only possibility. The same applies to the provisional diagnosis of functional illness. Nevertheless, an early acknowledgement that the most likely diagnosis is non-organic serves to reinforce that the doctor retains clinical acumen, assuming that there are valid reasons for placing the ‘functional’ label as the most likely diagnosis.

To consider what some claim a diagnosis of last resort necessitates the clinician appreciating those features of non-organic diseases that justify placing them at the top of the diagnostic ladder. What follows in this chapter is the evidence upon which a diagnosis of non-organic disease can be suspected as the principal diagnosis.

Observation

In earlier chapters it was proposed that an astute receptionist may be invaluable in suspecting psychological illness. A patient may display a range of behaviours that lead to the suspicion of non-organic disease. A receptionist may note how the behaviour changes when the attending doctor is, or is not, in the waiting room. The way the patient walks into the room or excessive complaint of pain without attendant signs may raise suspicion. These features suggest malingering and patient complicity in the claim of symptoms and signs. The patient may benefit from a fraudulent claim, as might occur following an accident. An experienced general practitioner will be atuned to such behaviour, which will not be discussed further in this chapter.

History

As was stated earlier, the taking of an accurate medical history remains a fundamental tool of the neurological consultation. Within the context of functional illness, other than the case of a malingerer who wilfully aims to confound the picture, the patient usually is unaware of the possibility of a non-organic diagnosis. As with so many neurological diagnoses, including non-organic neurological presentations, the doctor must maintain a high index of suspicion. This is imperative if the diagnosis is to be identified as early as possible. Often the diagnosis of non-organic disease emerges because the history in these cases makes little sense, does not suggest a diagnostic label and confuses, rather than assists, the clinician.

Whenever the history fails to offer clinical diagnostic direction, the possibility of functional illness should arise. In these circumstances functional illness should not climb the diagnostic ladder, but merely be included among the potential diagnoses. It is part of the differential options but lacks credibility to be a principal choice. The provisional diagnosis should be based on positive factors, and confusion is far from positive, but may provide an important clue.

Having made the distinction, history is the tool that differentiates tension-type headache from migraine. Tension-type headache may well be a ‘front’ for non-organic disease. Particularly in societies in which physical fitness is a primary requirement, as is the case for members of the armed forces, patients often find it unacceptable to present with complaints of a psychological nature. Once tension-type headache becomes apparent, then the general practitioner is in an ideal position to seek and deal with the cause of the tension. The same applies to various complaints of pain. An example of this is the chest pain that accompanies da Costa’s syndrome, which is a left inframammary pain attached to stressful situations. It is unlike the pain that reflects ischaemic heart disease or chest infection. This should raise the red flag of probable psychological illness but this warning does not negate the need to investigate for both cardiac and pulmonary disease. An early suggestion that the primary diagnosis is most likely non-organic, allows a strengthening of the doctor–patient relationship and potential for mutual respect while the auxiliary investigations proceed.

The differentiation between epileptic seizures and non-organic, so-called pseudo-seizures, also referred to as ‘non-epileptic’ seizures, is based on meticulous history taking. There are some features that assist in the differentiation, including: whether the eyes were open or shut during the seizure (eyes are usually open during an epileptic seizure); what post-ictal features existed (people after a seizure are often confused, disoriented, fatigued and may complain of headache while those with non-organic seizures may not experience these symptoms); if there was tongue biting or biting of the buccal mucosa; as well as possible incontinence of urine and/or faeces. While none of these are pathognomic of true epileptic seizures, they add to the weight of evidence, which may differentiate between the two. Absence of features associated with epileptic seizures offers the doctor the opportunity to explore causes of functional illness. Raising this with the patient demonstrates an understanding of the subject matter and encourages trust and respect.

Within these scenarios the doctor can both reassure the patient that there is probably nothing organically wrong, while concurrently conducting the tests to prove this to be the case. Unlike the situation in which non-organic diagnosis is the diagnosis of last resort, early identification and intervention reduces the risk of the patient adopting the ‘sick’ role.

The doctor needs to explain the reason, based on the available evidence, as to why functional illness is at the top of the list of diagnoses. While the initial response may be disagreement, it reinforces the integrity of the doctor; as will be reinforced if later findings support the earlier supposition of non-organic disease. This allows the doctor and patient to build a relationship on trust, in which the intimacy of the relationship may permit the doctor to explore issues that might otherwise be off-limits. It may provide the portal to introduce psychological or psychiatric support.

Examination

Neurology is a delightful speciality because the signs must fit the anatomical dictates. If these fail to match what is expected, then they provide unequivocal evidence of non-organicity. In previous chapters the approach to neurological examination was dissected to allow the doctor to complete the process in a formalised, traditional fashion. What follows will use this approach to demonstrate features that are anatomically unsound. Where there is incongruity between clinical findings and anatomical parameters, there is unequivocal evidence of functional illness.

A claim of monocular diplopia, in the absence of nystagmus, lenticular dislocation as occurs in Marfan’s syndrome or other obvious pathology, indicates that the final diagnosis is most likely non-organic. Nevertheless, the patient requires proper cranial nerve testing. The claim of monocular diplopia should be a red flag for non-organic disease. Further investigation is dependent upon what other features have emerged, either during the history taking or other examination. Recently, a patient complaining of monocular diplopia was shown on MRI to have her lens dislocated to the back of the globe. This confirmed the potential, thereby dispelling the diagnosis of functional illness. Suspicion of non-organic disease does not suggest the general practitioner should not fully investigate for organic diseases. It allows the doctor to reassure the patient that the investigations are expected to be negative and thus reduce fear of probable devastating findings. This in turn serves to reduce the risk of ‘sick’ role-play by the patient.

The trigeminal nerve provides a most fertile ground for the definition of functional illness. As demonstrated in Chapter 3, the trigeminal nerve has defined anatomical demarcation of its boundaries of sensory representation (see Figs 5.1 and 5.2).

FIGURE 5.1 Trigeminal nerve (I).

FIGURE 5.2 Trigeminal nerve (CN V).

As the interaural plane defines the limit of the ophthalmic branch of the CN V, it follows that sensory change occurring at other than this plane is anatomically unsound. Many patients with non-organic disease will identify sensory change at the start of the hairline on the forehead. This provides unequivocal evidence of functional illness. The same applies when the patient claims the angle of the jaw as the site of sensory change. The angle of the jaw, below the line from the tragus of the ear to the midline (just below the jaw), is innervated by high cervical roots (especially C2 and C3) (see Figs 5.1 and 5.2). A patient identifying sensory change at the angle of the jaw offers unequivocal evidence of functional illness.

Predetermined sensory maps are not restricted to the cranial nerves. The torso is also divided into dermatomes that establish expected, affected areas according to anatomic landmarks. All sensation in the body, be it head or torso, changes at the midline. If a patient reports altered sensation which does not respect the midline, be it on the face (with sensory change over the cheeks rather than the midline) or on the body (be it the nipple line rather than the midline), this is further unequivocal support for the diagnosis of functional illness. Similarly, the midline posteriorly (head and torso) defines the anatomical landmark for dermatomal separation of right and left, and failure to respect this is tantamount to non-organicity.

Every clinical practice should have the dermatomal map available for scrutiny. An invaluable reference is Aids to the examination of the peripheral nervous system (O’Brien 2010), which is a MUST for all serious clinicians interested in the nervous system. There are some useful landmarks to remember that will allow the examiner to localise lesions with ease (see Box 5.1). A more complete dermatomal map has not been provided here as the above reference is both cheap and invaluable.

The cranial nerves are not the only source of definition of non-organicity. Patients who complain of weakness of muscles, when asked to exert maximal effort from a specific muscle or muscle group, may show activation of antagonistic muscle groups. An example of this might be the patient claiming weakness of the triceps muscle, but when strength in this muscle is tested there is clear evidence of biceps involvement (see Fig 5.3).

FIGURE 5.3 Use of antagonistic muscles.

Activation of antagonistic muscle(s), within the context of testing ‘maximal’ power of a specific muscle or muscle group, offers unequivocal evidence of suboptimal effort. This does not mean the patient is aware of so acting on a conscious level, but does offer clear evidence of functional illness.

Another region in which weakness may reveal functional illness is in the examination of lower limb power in a patient who is lying down (see Fig 5.4).

FIGURE 5.4 Hoover’s sign.

Hoover’s sign relies on Newton’s third law—namely, ‘for every action there is an equal and opposite reaction’. The patient is asked to lift up one leg with maximal power against resistance while lying flat. The doctor resists the effort to lift this leg while placing their other hand under the heel of the other foot. Based on Newton’s third law this foot must push down to maximise the upward effort of the opposite leg. In the patient who is not pushing up with maximal effort, the doctor will not feel the downward thrust of the heel, a positive Hoover’s sign. The doctor may even be able to lift the heel effortlessly because of the lack of downward force. This further emphasises non-organicity. A positive Hoover’s sign provides unequivocal support for the diagnosis of functional illness. Such finding opens the way to explore the underlying cause for such behaviour.

As demonstrated in Chapter 4, neurological diseases assume a set pattern of presentation. This is particularly so for upper motor neurone deficit which affects antigravity muscles (Fig 5.5). Damage, as evidenced by hemiparesis, causes a set pattern of weakness, with resultant unequal power in the muscles that oppose the antigravity muscles (Fig 5.6).

FIGURE 5.5 Antigravity muscles.

FIGURE 5.6 Spastic posture—non-antigravity muscles.

A patient presenting with one-sided weakness suggestive of hemiparesis, who does not have weakness in the distribution of the antigravity muscles and who has downward plantar responses, provides clear evidence of functional illness. This demonstrates the need for further investigation and may suggest the need to involve either a clinical psychologist or psychiatrist.

Conclusion

As stated earlier, a detailed neurological history and examination arms the doctor with an appreciation of what to expect. When the findings fail to live up to expectation, then the doctor should consider ‘functional illness’ among the differential diagnoses. Just because ‘functional illness’ appears on the list of potential diagnoses, it does not stop the doctor fully investigating other possibilities.

Some findings, such as: non-anatomical sensory deficit on the face; activation of antagonistic muscles when exerting ‘maximal’ power; inappropriate pattern of weakness; or a positive Hoover’s sign, provide unequivocal evidence of functional illness. In these circumstances functional illness may climb to the top of the diagnostic ladder, in which case it may be appropriate to discuss this with the patient early in the clinical course. It would also be appropriate to involve a psychologist or psychiatrist early in the process. In this context it may be a positive move to reassure the patient that subsequent investigations are not being conducted to find an alternative, as yet unsuspected, diagnosis but rather to protect the patient from any possible omission. Such early acknowledgement of suspected non-organic cause for the presentation may serve to obviate chronic ‘sick behaviour’ and allow early intervention, as well as protecting against subsequent investigation to exclude differential diagnoses.