11 The nervous system

Medical students often approach the neurological examination with trepidation, no doubt partly because of the complexities of the nervous system and partly because of the difficulties sometimes experienced in attempting anatomical localisation on the basis of abnormal physical signs. The problem for the student, however, often begins with a failure to acquire the skills necessary to elicit those signs. If they are not identified correctly, mistakes in interpretation and diagnosis inevitably follow.

This chapter summarises the examination of the central and peripheral nervous systems, although it will seldom be necessary to examine all the areas covered. Selection is influenced partly by the patient’s history but also by cooperation, conscious state and level of fatigue. Certain examination techniques demand a good deal of both patient and examiner and if responses become erratic it is better to return to the examination later. Students, and sometimes doctors, are prone to examine only those areas immediately accessible with the patient supine. Remember to turn the patient over in order to assess the spine and the muscles of the shoulder and pelvic girdles. Always record your findings in full, avoiding irritating acronyms (e.g. PERLA for pupils equal, reacting to light and accommodation) and, if your examination has been limited, state exactly what you have done (rather than just ‘CNS’ followed by a tick). Remember that physical signs can alter, sometimes rapidly, and repeating your examination can give you useful insight into the mechanisms of certain disorders.

The cortex

STRUCTURE AND FUNCTION

On the basis of differences in histological structure, distinct areas can be identified within the cerebral cortex (Fig. 11.1). Tracts within the cortex comprise efferent pathways such as the pyramidal system, afferent pathways such as the thalamocortical projections, association fibres passing from regions within the hemisphere and commissural fibres connecting regions contralateral to one another. Surrounding the primary cortical areas for movement, sensation and vision are the cortical association areas. For example, the lateral geniculate body projects not just to the visual cortex (area 17) but also to areas 18 and 19, parts of the visual association cortex (Fig. 11.1).

Fig. 11.1 Lateral and medial aspects of the cerebral hemisphere showing some of Brodmann’s cortical areas.

The frontal lobe is separated from the parietal lobe posteriorly by the central (rolandic) sulcus, while the temporal lobe lies below the lateral (sylvian) sulcus. The boundaries of the parietal, temporal and occipital lobes are not defined by a specific sulcus (Fig. 11.2).

Fig. 11.2 Lateral surface of the cerebral hemisphere.

The brain is supplied by paired internal carotid and vertebral arteries. The former terminate in the anterior and middle cerebral arteries, the latter in the basilar artery, which ends by forming the posterior cerebral arteries (Fig. 11.3). An anastomotic system at the base of the brain (the circle of Willis) connects these various components. The lateral surface of the cortex is supplied predominantly by the middle cerebral artery. The anterior cerebral artery supplies a strip of cortex spanning its superior margin, while the posterior cerebral artery supplies the occipital lobe and the inferior aspect of the temporal lobe (Fig. 11.4). Normal cerebral blood flow, at approximately 55 ml/100 g/min, represents approximately 15% of cardiac output. The level of blood flow is largely dependent on the Pco₂ of arterial blood. Vasodilatation and increased flow occur as Pco₂ rises. During a specific task orientated to speech, vision, hearing or motor activity, a focal increase in flow occurs in the appropriate part of the cortex.

Fig. 11.3 Arteries at the base of the brain.

Fig. 11.4 The arterial supply of the lateral surface of the cerebral hemisphere.

The ventricular system contains cerebrospinal fluid (CSF) which originates predominantly in the choroid plexuses of the lateral ventricles, then circulates through the third ventricle and aqueduct before reaching the fourth ventricle. The CSF exits through the foramina of the fourth ventricle and is eventually reabsorbed through the arachnoid villae. The rate of CSF production is approximately 120 ml/24 h.

Acquisition of memory requires a number of stages. All data, whether visual or verbal, are recorded temporarily in a short-term pool. A selective and active process then passes some of the data into a long-term memory store. Finally, an active process of retrieval restores the memory to consciousness. Conventionally, memory is divided into immediate, recent and remote components, although these divisions are not absolute. Immediate or short-term memory lasts a few seconds; recent memory relates to activities or events occurring within a few hours or days and remote memory to events of the past, for example, the individual’s youth. Structures particularly associated with learning storage include the hippocampi, the mamillary bodies and the dorsomedial nuclei of the thalami – the limbic system. Remote memory, however, can be retrieved even if these structures are damaged, suggesting that it is stored predominantly in the association cortex appropriate to the memory modality.

Visuospatial ability is dependent mainly on nondominant parietal lobe function. Language function is located in the left hemisphere in around 99% of right-handed individuals. For left-handed individuals, some 60% have language dominance in the left hemisphere, with 40% in the right hemisphere. Something like 80% of all left-handed individuals have mixed dominance, with language represented in both hemispheres. Within the hemisphere, a posteriorly placed area (Wernicke) is concerned with the comprehension of spoken language and an anterior area (Broca) with language output. The two are connected by the arcuate fasciculus (Fig. 11.5). The integration of the auditory and visual data required for reading and writing is achieved by the angular gyrus (area 39) (Fig. 11.1).

Fig. 11.5 Broca’s and Wernicke’s areas and their connecting arcuate fasciculus.

Although certain functions can be localised to specific cortical areas, other aspects of higher cortical function are represented more diffusely.

SYMPTOMS

Many of the symptoms arising from a disorder of higher cortical function will be more evident to a close friend or relative than to the patient. Areas to cover, although some will be more evident during formal examination, are the following.

Examination

Assessment of the mental state begins as soon as the patient enters the consulting room. During the history-taking it will become apparent if there is an alteration of mood, whether there is any disturbance in the comprehension or production of speech and whether the patient has retained insight. The physical appearance can be helpful. Demented patients often have a bemused look, wondering why they are seeing a doctor. Evidence of self-neglect is usually concealed by the attentions of friends or relatives. The way in which the patient responds to questioning is of value in diagnosis. Demented patients tend to be inert and apathetic but a similar impression can be given by depressed individuals.

ORIENTATION

Begin by assessing the patient’s orientation in time and space. Establish the patient’s age and ask the time, date and the name of the hospital or clinic in which the interview is taking place. Ask either how long the patient has been in hospital or the duration of the interview.

MEMORY

Immediate recall

For testing recall, use digit repetition, although a normal response also requires intact attention and adequate comprehension. Start with two or three figures at 1s intervals, avoiding recognisable sequences. Normal individuals can repeat a 5–7 digit sequence. Reverse repetition of a set of digits is a more difficult process not solely dependent on memory. Normal individuals can achieve a 4–5 figure sequence. The performance of serial sevens (subtracting seven serially from 100) is dependent on many factors. An abnormal response to this test does not specifically identify the patient with dementia.

Recent memory (new learning ability)

The examination begins by asking the patient about recent events, although interpretation of the responses must take account of the patient’s premorbid intelligence and level of culture. Next ask the patient to memorise three objects or, alternatively, a name, an address and a flower. Repeat the objects immediately and ask the patient to repeat them, so that they have clearly been registered. Over the next 10 min distract the patient so that there is no opportunity for mental rehearsal, then ask the patient to repeat the data. Most normal individuals can recall all the data at 10 min and 75% at 30 min. For further testing of verbal recall, give the patient a short story containing a standard number of items and, as soon as the story has been told, ask the patient to recount it.

Visual memory can be tested by displaying drawings for a 5 s period then asking the patient to reproduce the design 10 s later. Patients with visuospatial disorders will have problems with the task even if their visual memory is intact. The copies can be graded on a four-point scale, with a score of two, for example, indicating a recognisable design containing minor flaws and three a near-perfect or perfect reproduction. Average individuals score two or three on each test item (Fig. 11.6).

Fig. 11.6 (a) Standard design and (b) reproductions scored from 0 to 3.

Remote memory

Ask the patient about schooling, childhood, work history, marriage and, if relevant, the ages of any children. The accuracy of the responses will need verification by a relative. Remote memory is spared in individuals with minor degrees of brain damage but will inevitably be eroded in people suffering from dementia.

Interpretation of proverbs tests both general knowledge and capacity for abstract thinking. Proverbs of increasing complexity are read out to the patient and their interpretation recorded. A simple proverb to interpret would be ‘A bird in the hand is worth two in the bush’; more difficult would be ‘People in glass houses should not throw stones’. Concrete responses, typically seen in demented individuals, fail to see beyond the immediate implications of the proverb. For example, a concrete response to the second example would be that the glass would get broken.

Constructional ability

Constructional ability can be tested by asking the patient to copy designs of increasing complexity (Fig. 11.7). A scoring system can be devised, low values for which correlate well with the presence of brain damage. When assessing the patient’s drawing, look for evidence of unilateral neglect, suggesting the probability of a contralateral parietal lobe syndrome.

Fig. 11.7 Drawings of increasing complexity to be reproduced by the patient.

GEOGRAPHICAL ORIENTATION

Evidence concerning this may have been forthcoming during history-taking but to test it specifically ask the patient to draw an outline of their native country, placing within it a few of the principal cities. From the figure it should be apparent whether or not the patient has an overall defect of geographical localisation or one based on neglect of one-half of the visual field (Fig. 11.8).

Fig. 11.8 Control (above); patient with left-sided neglect (below).

SPEECH AND SPEECH DEFECTS

Determine the patient’s handedness. Asking which hand is used for writing is insufficient because some left-handed individuals have been taught to write with their right hand. Ask which hand is used for holding a knife, using a hair brush, using a screwdriver or for playing racket sports. Check on the family history of handedness.

Dysarthria

This is a defect of articulation without any disturbance of language function. Dysarthric patients have a normal speech content and, if they are able to write, their script will be free of dysphasic errors. Production of certain consonants depends on specific parts of the vocal apparatus; P and B are labial sounds, D and T are lingual.

Dysphonia

Dysphonia is a defect of speech volume and is usually the result of a disorder limiting the excursion either of the muscles of respiration or of the vocal cords.

Dysphasia (aphasia)

This is a defect of language function in which there is either abnormal comprehension or production of speech or both. Much of the patient’s language function will have been tested, although not deliberately, while taking the history. Seldom is there no spontaneous speech, although in certain types of dysphasia, the patient may be reduced to uttering short, meaningless phrases. Dysphasic speech lacks grammatical content, displays word-finding difficulty and contains word substitutions (paraphasias). Paraphasias are either whole word substitutions (verbal, e.g. bread for table), syllable substitutions (literal, e.g. speed for feed) or complete nonsense words (neologisms, e.g. tersh).

Fluency

Fluency may be defined as the amount of speech produced in a given period of time. Nonfluent speech, therefore, contains a limited number of words. Typically, the patient makes a greater effort in speech production, the output is often dysarthric and the phrase length limited. The overall result is a loss of rhythm and melody (dysprosody). Fluent dysphasia is near or even above normal in terms of output. Melody tends to be retained and phrase length is normal. Despite this, the patient fails to produce critical, meaningful words and output is incoherent. Verbal fluency can be formally tested by asking the patient to name as many objects as possible in a particular category (e.g. fruits and vegetables) in a set length of time.

Comprehension

In testing comprehension, increasingly complex questions can be asked but all should be answerable by a simple yes or no response. A substantial number of questions requiring randomly distributed yes or no responses are needed to avoid errors in interpretation. Avoid asking the patient to perform a skilled task; those individuals with apraxia will fail even if their comprehension is intact.

Repetition

Start by asking the patient to repeat simple words, then give sentences of increasing complexity. Patients with repetition difficulty often have a particular problem repeating ‘no, ifs, ands or buts’.

Naming

A naming defect is found in virtually all dysphasic patients. Point to a succession of items, and ask the patient to name each one. Use objects commonly and less commonly encountered and mix the categories rather than restrict the test to, say, parts of the body.

READING

Reading assessment must take account of educational background. Ask the patient to read aloud, then test comprehension by asking questions requiring simple yes or no responses.

WRITING

Dysgraphia is an inevitable accompaniment of dysphasia. Begin testing writing ability by asking the patient to write single words, then sentences, initially writing them spontaneously and then in response to dictation. After checking word content, note whether the writing is crammed into one side of the page, suggesting the possibility of unilateral neglect.

PRAXIS

Apraxia is a disorder of skilled movement not attributable to weakness, incoordination, sensory loss or a failure of comprehension. The problem in movement may be confined to the limbs, to the trunk or even to the buccofacial musculature. Historically, apraxia was separated into two main categories. In ideational apraxia, destruction of the motor programming area in the supramarginal gyrus impairs the conception of an action, leading to defecits in using tools or performing actions to verbal commands, though sparing the ability to mimic. Ideomotor apraxia results from separation of the motor programming area from the motor and premotor areas. Here conception of the action is spared but not the ability to perform it. The nomenclature of apraxia has become much more complex, along with the recognition that ideational apraxia is a less definable entity.

Start by asking the patient to carry out a particular task (e.g. ‘pretend to use a screwdriver’). If the patient is unable to perform the task, do it yourself and then ask the patient to copy your movement. If a response is still not forthcoming, provide the object in question and ask the patient to demonstrate its use. These three tiers of command are in descending order of difficulty for the apraxic patient. Instructions that will test relevant movements include ‘put out your tongue’, ‘pretend to whistle’, ‘salute’ and ‘show how you would use a toothbrush’. For whole body movements, ask the patient to stand to attention or stand as if about to start dancing. A more complex motor sequence is tested by asking the patient to go through a series of related movements. For example, taking the cap off a toothpaste tube, squeezing the toothpaste onto a brush, then replacing the cap.

Right–left orientation

A proportion of normal individuals have some problem with right–left orientation. Patients who are dysphasic can have problems understanding your commands. Start testing with simple tasks (e.g. ‘show me your right hand’) then gradually increase their complexity (e.g. ‘put your left hand on your right ear’).

Agnosia

Patients with visual agnosia are unable to recognise objects they see, despite intact visual pathways and speech capacity. Show objects to the patient, asking the patient to name each one and then allow the patient to manipulate the object to see if this improves recognition. Other forms of agnosia that can be tested include the ability to name and recognise individual fingers (finger agnosia) and colours (colour agnosia).

Conclusion

It is clearly not appropriate to go through such an extensive testing of higher cortical function in every patient. Screening tests have been devised that allow a rapid assessment of function. Such tests, for example, the mini mental-state test (Fig. 11.9) are useful, although their limitations need to be remembered when using them for screening purposes. A score of 20 or less suggests the possibility of a cognitive disorder, particularly dementia.

Fig. 11.9 The mini mental-state test.

Stroke firmly across the palmar surface of the hand from the radial to the ulnar aspect. In a positive response, the examiner’s hand is gripped by the patient’s fingers, making release difficult. A foot grasp reflex is elicited by stroking the sole of the foot towards the toes with the handle of the patella hammer. A positive response leads to plantar flexion of the toes.

Clinical application

DEMENTIA

Dementia is defined as a disorder or progressive memory impairment coupled with at least one other cognitive deficit (aphasia, apraxia, agnosia or a defect of executive function), though in, for example, Alzheimer’s disease the memory impairment may antedate the other features by some years. The majority of patients with dementia have Alzheimer’s disease. Most of the remainder has either cerebrovascular disease or a mixed pathology. In the early stages of dementia, the most prominent symptoms are apathy and lack of concentration, together with defects in memory, and performance. Later, word-finding difficulty appears, with impaired comprehension and paraphasic substitutions. The patient becomes apraxic. There is a surprisingly poor correlation between the presence of dementia and the size of the cortical sulci as demonstrated on computerised tomography (CT). Ventricular size provides a better correlate (Fig. 11.11).

Fig. 11.11 CT scan of a patient with dementia.

AMNESIA

Damage to the limbic system results in a failure to learn new memories (antegrade amnesia) associated with a defect of memory for the more recent past (retrograde amnesia). In some instances, the patient confabulates responses, particularly soon after the onset. Immediate memory remains intact. Conditions causing this picture include herpes simplex encephalitis and alcoholism. Unilateral temporal lobe lesions can have a selective effect on verbal or visual memory, according to whether the dominant or nondominant hemisphere is affected.

Here the patient has fluent, easily articulated speech but there are frequent paraphasias and meaning is largely absent. Comprehension and repetition are severely impaired and attempts at naming produce paraphasic errors. The patient is often described as confused.

Conduction aphasia

Conduction aphasia is fluent but not to the degree seen in Wernicke’s aphasia. Interruptions to the speech rhythm are frequent but there is no dysarthria. Naming is imperfect but comprehension good. Despite this, repetition is severely abnormal. Reading, at least out loud, and writing are impaired. The condition occurs with disruption of the arcuate fasciculus connecting the posterior temporal lobe to the motor association cortex (Fig. 11.12). Cerebrovascular disease is the most common cause.

Transcortical sensory aphasia

Transcortical sensory aphasia is fluent but frequently interrupted by repetition of words or phrases initiated by the examiner (echolalia). Despite the readiness and accuracy of the patient’s repetition, comprehension is severely impaired. Naming is poor and reading comprehension defective. The responsible anatomical site is less well localised than for some of the other forms of aphasia but lies in the borderlands of the temporal and parietal lobes of the dominant hemisphere.

Anomic aphasia

Anomic aphasia is fluent and interrupted more by pauses than by paraphasic substitutions. Comprehension is relatively preserved, repetition is good and naming is affected but to a varying degree. There is no specific anatomical location. Anomic aphasia can be the final stage of recovery from other forms of aphasia and is seen with both structural and metabolic brain disease.

Global aphasia

Global aphasia affects all aspects of speech function. Output is nonfluent and comprehension, repetition, naming, reading and writing are all affected, often to a severe degree. The causative pathology occupies a substantial part of the language area of the dominant hemisphere and is usually an extensive infarct in middle cerebral artery territory.

DYSLEXIA AND ALEXIA

Dyslexia refers to developmental disorders of reading, and alexia to disorders secondary to acquired brain damage. Alexia with agraphia is found with lesions of the angular gyrus of the dominant hemisphere. Alexia without agraphia in right-handed individuals is associated with lesions affecting both the left occipital cortex and the splenium of the corpus callosum and is most commonly the result of an occlusion of the posterior cerebral artery.

APRAXIA

The pathway involved in performing a skilled task to command begins in the auditory association cortex of the dominant hemisphere then passes to the parietal association cortex, subsequently travelling forwards to the premotor cortex and finally the motor cortex itself. Interruption of this pathway at any point results in an ideomotor apraxia affecting both the dominant and nondominant hands (Fig. 11.13). The pathway from the dominant to the nondominant premotor cortex (D–D) passes through the anterior corpus callosum. A lesion there will produce an apraxia confined to the left hand. Whole body movements tend to be relatively spared even when limb ideomotor apraxia is substantial. Ideational apraxia is usually the consequence of bilateral hemisphere lesions or predominant left hemisphere dysfunction.

Fig. 11.13 Pathway involved in the formulation and performance of a skilled motor task.

RIGHT–LEFT DISORIENTATION

Right–left disorientation is usually the result of a posteriorly placed dominant hemisphere lesion. Gerstmann’s syndrome comprises right–left dis- orientation, finger agnosia, dysgraphia and dyscalculia. If all four components are present, the causative pathology is likely to lie in the dominant parietal lobe, though doubt has been expressed regarding its specificity.

VISUAL AGNOSIA

One form of visual agnosia is caused by a disconnection between the visual cortex and the speech area. Patients can recognise objects and demonstrate their use but are unable to name them. Bilateral temporo-occipital lesions are the usual cause. In the other form of visual agnosia, recognition of objects fails but their use can be demonstrated if the object is placed in the hand. In other words, sensory information can bypass the defect of visual recognition, which is a consequence of damage to the visual association cortex in both hemispheres, usually vascular in nature.

PRIMITIVE REFLEXES

The palmomental reflex is found bilaterally in some normal individuals but a unilateral palmomental reflex suggests a contralateral frontal lobe lesion. Snout and suckling reflexes are elicited in patients with diffuse bilateral hemisphere disease. Bilateral grasp reflexes are of limited localising value but a unilateral response is associated with pathology in the contralateral frontal lobe. A foot grasp or tonic plantar reflex can be one of the earliest signs of a frontal lobe lesion.

The psychiatric assessment

Make sure that the patient understands who you are, and the purpose of the interview. Privacy is particularly important when sensitive issues are being explored. To begin with, avoid making notes, as this can detract from the relationship you are trying to establish with the patient. During this preliminary phase, observation of the patient’s posture, gestures and facial expression may provide information regarding mood and feeling. The depressed patient appears apathetic, has little expressivity and may well be reluctant to discuss the history. The agitated patient is restless.

HISTORY OF PRESENT CONDITION

This proceeds in much the same way as history-taking from a patient with a physical complaint. Indeed, physical symptoms often predominate in those individuals with a primary psychiatric illness. Try to establish when the patient last felt well, as a means of determining the overall length of the history and as a means then of establishing the chronological order of subsequent symptoms. If necessary, interrupt the patient if there is digression into other areas, for example current social issues, through making clear that you are interested in those issues, and will wish to return to them later. Sometimes directive questions are needed to focus the patient’s attention on a particular symptom, for example headache, in order to explore that symptom in greater detail. As the history proceeds, open questions will be partly replaced by closed questions, answerable by a simple yes or no response. Sometimes signs of emotional distress may appear as certain issues are raised. Rather than ignoring these, gently probe them, even if this temporarily diverts the course of the history.

Quite often, patients only indirectly refer to stressful issues by giving oblique reference to them in the course of describing their physical symptoms. Try to pick up these cues and develop the relevant issue. Failure to detect them will deter the patient from discussing them further.

Many symptoms are common to both physical and psychiatric illness but others are more specifically within the territory of psychiatry.

SPECIFIC SYMPTOMS

Mood

Enquire whether the patient, or a relative, has noticed any mood change. A particularly valuable question when screening for depression is whether the individual has lost pleasure in their normal activities (anhedonia). Supplementary to this will be enquiries regarding sleep pattern, loss of libido and suicidal ideation. Sometimes the patient denies flattening of mood, when that is all too evident from the interview. Such discrepancies should be carefully recorded.

Patients will usually complain of anxiety but sometimes its somatic manifestations, for example palpitations, sweating and tremulousness, predominate. The anxiety may be chronic and spontaneous or be triggered acutely by a specific stimulus – phobic anxiety.

Patients seldom complain of euphoria – a feeling of limitless physical and mental energy. There is likely to be a pressurised manic quality to the patient’s conversation, coupled with physical restlessness.

Abnormal thoughts

These will be elicited only by sensitive questioning. The patient can be understandably reluctant to reveal certain abnormal thoughts. It may be apparent from the interview that the patient’s thought pattern is difficult to follow or that abnormal thoughts have pervaded the conversation. Ask patients about paranoid ideas, in other words, whether they feel people are against them. Ask whether certain thoughts or ideas regularly intrude into their thinking, or whether they believe their thoughts are being interfered with or influenced by external agencies. Thought disorders include the following.

Delusions

These are beliefs which can be demonstrated to be incorrect but to which the individual still adheres. Members of the Flat Earth Society are deluded. Often there is an element of reference, in other words that actions or words are directed specifically at that individual even if they appear on a global platform, for example television. Paranoid delusions contain a persecutory element. Delusions of worthlessness are particularly associated with depressive illness.

Obsessions

These are recurrent thoughts which often result in the performance of repetitive acts (compulsions). The patient is aware that they are inappropriate but cannot resist returning to them or acting upon them. Examples of obsessional thought include convictions that a particular individual is antagonistic or that a spouse is unfaithful.

Symptoms and signs

Somatic and psychic symptoms of anxiety and depression

	Anxiety	Depression
Somatic	Palpitations Tremor Breathlessness Fatigue Diarrhoea Sweating	Altered appetite Constipation Headache Bodily fatigue Tiredness
Psychic	Feelings of tension Irritability Difficulty sleeping Fear Depersonalisation	Apathy Poor concentration Early morning waking Diurnal mood swing Retardation Guilt

Abnormal perceptions

These are auditory or visual phenomena that other individuals are not aware of.

Hallucinations are experiences that have no objective equivalent to explain them. They are predominantly visual or auditory but can occur in other forms, for example of smell or taste in patients with complex partial seizures. Visual hallucinations can be unformed, for example an ill-defined pattern of lights, or formed, the individual then describing people or animals, often of a frightening aspect. Visual hallucinations are more often a feature of an organic brain syndrome, e.g. delirium tremens or adverse drug reaction, than a functional psychosis, e.g. schizophrenia. Auditory hallucinations are also either unformed or formed. They are found more often in the functional psychoses than in organic brain disease. The voices can take on a persecutory quality in schizophrenia and an accusatory element in depression. In déja and jamais vu, intense feelings of a relived experience or a sensation of strangeness in familiar surroundings occur, respectively. Both can be a feature of everyday life but when pathological are usually epileptic. Illusions are misinterpretations of an external reality: all of us have this when watching a magician at work. In depersonalisation, the individual feels a detachment from the normal sense of self; in derealisation, the individual feels a detachment from the external world. Both occur in neurotic illnesses but also, periodically, in normal individuals.

Cognition

The assessment of higher cortical function has already been discussed. It is necessary to distinguish cognitive impairment due to dementia from cognitive impairment due to delirium. In the latter there is clouding of consciousness, usually manifested as reduced awareness of, or response to, the environment.

THE FAMILY HISTORY

Begin by obtaining details of the patient’s father and mother, in terms of their current age (or age at death), their own quality of health, whether they had any history of psychiatric disorder and the quality of the patient’s relationship with them. Ask similar questions about the patient’s siblings. Questions regarding the patient’s own children are usually included in the personal history. Genetic factors are particularly strong in schizophrenia and manic-depressive psychosis.

THE PERSONAL HISTORY

Childhood

It is unlikely patients will have accurate details of their birth or early development unless there was a particular problem with them. A direct question to the patient regarding whether they were happy or unhappy in childhood is useful. Some ‘happy’ responses turn out to be rather less so with further delving. If there is an expression of remembered unhappiness, explore it further in terms of relationships with parents and any physical illness.

Schooling and further education

Establishing the details of this is helpful in forming an assessment of the patient’s premorbid intelligence. At the same time, enquire about friendships or a tendency to isolation, and about teasing or bullying.

Sexual development

For female patients, enquire about the age of the menarche and how they attuned to adolescence in terms of menstruation and sexuality. For men, discussion should include whether their sexuality could be discussed in the home and how they acquired their sexual experience. Further issues relating to sexual development, for example homosexual experiences, are best left, at this stage, for the patient to raise.

Marital history

An overall outline includes the age of the spouse when the marriage occurred, the overall quality of the relationship, the state of the sexual relationship and details of any unease.

Occupational history

Ask how many jobs the patient has had, reasons for leaving previous posts, the quality of relationships in the workplace and the level of job satisfaction. If there has been one or more periods of unemployment, explore what effect this has had on the patient’s overall welfare.

PAST MEDICAL HISTORY

This follows the usual pattern, and includes history of both physical and mental illness if these have occurred.

DRUG HISTORY

Determine alcohol consumption, but be aware of the possibility that the figure does not correspond to actual intake. Features suggesting alcohol dependency include early morning drinking, morning vomiting, taking a drink before an interview, erratic work attendance and drinking in isolation. Ask about narcotic exposure, the use of softer drugs such as cannabis and exposure to tranquillisers. If the patient is using codeine derivatives, ascertain for what purpose and the dosage.

PERSONALITY PROFILE

Evidence suggesting changing personality and mood is often better provided by colleagues, relatives or friends than by the patient. Questionnaires exist for the assessment of personality, but even without them the patient’s attitude and behaviour, in terms of work and social relationships, personal drive, level of dependence, ambition and authority and response to stress will indicate the nature of the patient’s personality.

Examination

The concept of the psychiatric examination needs to be interpreted broadly. A physical examination is necessary but the most telling diagnostic details will be revealed by an exploration of the patient’s mental state, emerging as much from the history as from the answers to specific questions.

Clinical application

ORGANIC MENTAL STATES

In organic mental states, a specific pathological basis for the mental disorder has been established. Acute forms include the toxic confusional states, characterised by alteration of the conscious level, disordered perceptions (e.g. visual hallucinations), restlessness and thought disorder. Almost any structural or metabolic disorder can trigger the reaction. Examples include encephalitis, head injury and alcohol withdrawal. The principal chronic organic mental state is dementia.

FUNCTIONAL MENTAL STATES

In functional mental states, a specific underlying pathological or metabolic cause has not been identified. Psychotic states are those in which the individual has lost insight and neurotic states are those in which insight is preserved. The distinction is not absolute, however, and the terms are best avoided. In affective disorders, for example, anxiety, depression and mania, an alteration of mood is a major feature of the illness.

Schizophrenia has been classified into a number of types, although the entities defined are not absolutely distinct. It is characterised by thought disorder, blunting of emotional responses, paranoid tendencies and perceptual disorders. Thought disorder leads to irrational conversation, in which the development of ideas is either blocked or moves suddenly into unconnected channels. The emotions are blunted and the patient becomes increasingly withdrawn. Delusions are prominent and frequently contain paranoid elements. Auditory hallucinations are particularly characteristic of schizophrenia.

OBSESSIONAL STATES

In obsessional states, a preoccupation with mental or physical acts predominates. An obsessional personality displays these characteristics but not to the point where they interfere with the normal activities of life. In obsessional states, however, the relevant thought or action takes on a compulsive quality, ineffectively countered by the patient. Obsessional symptoms can feature in other psychiatric illnesses.

Symptoms and signs

The psychiatric patient

A full examination is performed to exclude any physical disorder that may contribute to the patient’s condition

HYSTERIA (CONVERSION HYSTERIA)

Hysteria is a disorder in which physical symptoms or signs exist for which there is no objective counterpart and which require, in the case of signs, an elaboration on the part of the patient of which he or she is unaware. Many of the symptoms are referred to the nervous system, for example, memory loss, paralysis, unsteadiness and visual impairment. Malingerers, on the other hand, consciously elaborate their disability.

HYSTERICAL PERSONALITY

Hysterical personality is distinct from hysteria, although individuals with this personality trait may develop conversion reactions. The hysterical personality is characterised by superficiality and shallow emotional responsiveness combined with a histrionic overwrought reaction to events.

Headache and facial pain

HEADACHE

Headache is a common complaint. Often the history suffices to separate the more serious causes. The length of history is particularly important, rather then necessarily the severity of the pain. Critical issues are whether the pain is continuous or intermittent and, if the latter, what is the duration of individual attacks. There may be particular precipitants for attacks, e.g. alcohol triggering an attack of cluster headache. Accompanying symptoms should be sought, e.g. nausea or vomiting. As for any pain, it is important to determine whether there are relieving factors. Patients often find it difficult to describe the quality of their pain – it may be helpful to provide them with a list of alternatives.

Examination

With recent onset headache, careful fundoscopy is essential to exclude the presence of papilloedema. Patients will seldom be seen during a migraine attack; between attacks their physical examination will be normal. Patients with tension (muscle contraction) headaches often show focal or diffuse scalp tenderness. Patients with cranial arteritis have tenderness of the scalp vessels which are more likely to show reduced rather than absent pulsation.

Differential diagnosis

Headache

• Migraine

• Tension headache

• Cluster headache

• Analgesic abuse headache

• Cranial arteritis

• Intracranial mass lesion

FACIAL PAIN

Facial pain is commonly of psychological rather than neurological origin. The first step in analysing facial pain is to determine whether it might be related to local causes, e.g. a dental abscess or focal sinus infection. Such causes will generally be associated with revealing local symptomatology, e.g. focal facial tenderness. Some facial pain is more or less continuous, but an important cause of severe, but episodic, facial pain is trigeminal neuralgia. Again seek the quality of the pain, its duration, if it is episodic, and its severity. Ask for specific triggers, e.g. particular trigger zones on the face, palpation of which can precipitate an attack of trigeminal neuralgia. In some instances facial pain is referred from the ear.

THE CRANIAL NERVES

The olfactory (first) nerve

STRUCTURE AND FUNCTION

The olfactory epithelium contains specialised receptor cells and free nerve endings, the latter derived from the first and second divisions of the trigeminal nerve. Unmyelinated axons from the receptor cells traverse the cribriform plate before synapsing in the olfactory bulb. From here, the olfactory tract passes backwards, dividing into lateral and medial roots in the region of the anterior perforated substance. The more important lateral root projects predominantly to the uncus of the ipsilateral temporal lobe.

Molecules derived from particular odours are absorbed into the mucus covering the olfactory epithelium. From here they diffuse via ciliary processes to the terminal processes of the receptor cells where they bind reversibly to receptor sites. This initiates an action potential in the olfactory nerve with a firing frequency related to the intensity of the stimulus.

Women have a more sensitive sense of smell than men. In both sexes, smell sensitivity declines with age. Many healthy individuals have difficulty naming or describing the quality of a particular odour even though they can distinguish it from others. The value of a particular odour for the testing of olfactory nerve function is determined principally by how selectively it stimulates the specialised receptor cells rather than the free trigeminal endings. Odours stimulating the latter include peppermint, camphor, ammonia, menthol and anisol. Highly selective stimulants of olfactory nerve endings include β-phenyl ethyl alcohol, methyl cyclopentenolone and isovaleric acid. Coffee, cinnamon and chocolate are useful everyday odours for the bedside testing of smell.

Symptoms and signs

Disturbance of smell

• Hyposmia-partial loss

• Anosmia-total loss

• Hyperosmia-exaggerated sensitivity

• Dyosmia-distorted sense

Differential diagnosis

Disturbances of olfaction

• Post-traumatic anosmia

• Postinfective anosmia

• Olfactory hallucinations in complex partial seizures

Olfaction is commonly disturbed by upper respiratory tract infection or local nasal pathology. Hyposmia can persist after an apparently banal viral illness and also after head injury. Smell sensitivity is diminished in dementia. Unilateral hyposmia is rarely the presenting symptom of a subfrontal meningioma. Olfactory hallucinations occur in complex partial seizures.

The optic (second) nerve

STRUCTURE AND FUNCTION

Two types of retinal photoreceptor, rods and cones, have been identified in humans. At the fovea only cones are found, with rods predominating in the periphery. Fibres from the nasal aspect of the fovea pass directly to the optic disc. Fibres from above and below the fovea pass almost directly but fibres from the temporal border pass almost vertically, both superiorly and inferiorly, before arching around the other foveal fibres on their way to the optic disc (Fig. 11.14). Axons in the papillomacular bundle originate in the cones of the fovea and occupy a substantial proportion of the temporal aspect of the optic disc. Fibres from the superior and inferior parts of the periphery of the retina occupy corresponding areas in the optic nerve. As the papillomacular bundle approaches the chiasm, it moves centrally. The crossing, nasal, macular fibres occupy the central and posterior part of the chiasm.

Fig. 11.14 Representation of the course of the retinal nerve fibres.

The superior peripheral nasal fibres cross more posteriorly than the ventral fibres, which loop slightly into the terminal part of the opposite optic nerve (Fig. 11.15). Crossed and uncrossed fibres are arranged in alternate layers in the lateral geniculate body. The optic radiation extends from the lateral geniculate body to the visual (striate) cortex, area 17 (Fig. 11.1). The ventral fibres of the radiation loop forward towards the tip of the temporal lobe. The visual cortex is situated along the superior and inferior margins of the calcarine fissure, extending approximately 1.5 cm around the posterior pole. The macular representation lies posteriorly, with dorsal and ventral retina above and below the fissure, respectively. The unpaired outer 30° of the temporal field is represented in the contralateral hemisphere at the anterior limit of the striate cortex (Fig. 11.16).