CASC Knowledge Essentials14 · Physical signs and investigations
14 · Physical signs and investigations
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Written by Resident Doctor Committee · Published
14.1 Four antipsychotic movement disorders
Syndrome | Recognise it | Treatment principle |
|---|---|---|
Acute dystonia | Painful sustained contraction, often soon after starting/increasing a dopamine blocker: torticollis, jaw spasm, tongue involvement, oculogyric crisis | Antimuscarinic treatment; airway involvement is an emergency |
Drug-induced parkinsonism | Bradykinesia, rigidity, reduced facial expression, shuffling gait ± rest tremor; often days to weeks | Review dose/drug; sometimes a short course of an antimuscarinic |
Akathisia | Inner restlessness, often with pacing, rocking or repeated leg movements, often after a medication change | Review dose/titration; propranolol may help selected patients |
Tardive dyskinesia | Repetitive involuntary movements, especially lip-smacking, chewing and tongue movements; usually longer exposure | Specialist medication review; antimuscarinics can worsen it |
Timing helps, but is not diagnostic. Metoclopramide and other dopamine-blocking antiemetics can cause the same problems. Procyclidine treats acute dystonia; severe cases may need parenteral treatment. Laryngeal dystonia can obstruct the airway.
Akathisia: the patient feels driven to move
The patient may describe being unable to sit still or feeling as though they must escape their own body. Visible movements can be subtle or absent. Mistaking this for worsening psychosis and increasing the antipsychotic can make it worse. Severe distress, including suicidal thoughts, needs direct assessment.
Restless legs has a different pattern: unpleasant leg sensations at rest, worse in the evening/night, relieved by movement. Propranolol is unsuitable in asthma, significant bradycardia or hypotension.
Describe the movement precisely
Term | Meaning |
|---|---|
Rest tremor | Present with the limb supported and inactive |
Postural tremor | Appears while holding a position |
Intention tremor | Increases as the limb approaches a target |
Rigidity | Resistance through passive movement, relatively independent of speed |
Cogwheeling | Ratcheting resistance, often from tremor superimposed on rigidity |
Spasticity | Velocity-dependent resistance; points to an upper motor neurone lesion |
Lithium: fine postural tremor may be an ordinary side effect; coarse tremor with ataxia or confusion suggests toxicity. Drug-induced parkinsonism is often symmetrical, but can be asymmetric. Persistence after withdrawal may reveal underlying Parkinson's disease.
Antimuscarinics can worsen cognition, constipation, urinary retention and tardive dyskinesia. Match the scale to the problem: Barnes → akathisia; Simpson–Angus → parkinsonism; AIMS → abnormal involuntary movements.
14.2 Weakness and neurological localisation
Pattern | Findings |
|---|---|
Upper motor neurone | Weakness, increased tone, brisk reflexes, extensor plantar response; an acute lesion can initially be flaccid |
Lower motor neurone | Weakness, reduced tone/reflexes; later wasting and fasciculations |
Polyneuropathy | Distal, often symmetrical sensory loss and reduced ankle reflexes; consider alcohol, diabetes and nutritional deficiency |
Cerebellar | Incoordination, intention tremor, dysdiadochokinesia, dysarthria, broad-based unsteady gait |
Functional weakness | Positive inconsistency between voluntary and automatic movement; may coexist with neurological disease |
MRC power: 0 = no contraction; 1 = contraction without movement; 2 = movement with gravity removed; 3 = against gravity; 4 = against resistance but weak; 5 = normal. Pain, fatigue and understanding can affect the result.
Hoover's sign: apparently weak voluntary hip extension improves during resisted flexion of the opposite hip. This supports functional weakness in context; it does not show that the person is pretending. Sudden focal weakness still needs an urgent neurological differential.
Romberg is not a cerebellar test in isolation
Standing uses vision, proprioception and vestibular input. Marked deterioration on closing the eyes suggests that vision was compensating for impaired position sense or vestibular input. Cerebellar unsteadiness is usually evident with the eyes open too.
Dysmetria means overshooting/undershooting a target; dysdiadochokinesia means impaired rapid alternating movements. Cerebellar limb signs are usually ipsilateral. Alcohol-related cerebellar damage, neuropathy and Wernicke encephalopathy can coexist; do not wait for the full Wernicke triad before treating.
14.3 Cranial nerves and visual pathways
Finding | Localisation |
|---|---|
Monocular visual loss | Retina or optic nerve, before the chiasm |
Bitemporal hemianopia | Optic chiasm; think of a pituitary-region lesion |
Homonymous hemianopia | Contralateral pathway behind the chiasm |
Superior homonymous quadrantanopia | Often contralateral temporal optic radiations |
Inferior homonymous quadrantanopia | Often contralateral parietal optic radiations |
Relative afferent pupillary defect | Asymmetric optic-nerve or substantial retinal dysfunction |
Facial sensation: trigeminal, except the angle of the jaw, which is supplied by upper cervical nerves. A peripheral facial-nerve lesion weakens the ipsilateral forehead and lower face; a supranuclear lesion often relatively spares the forehead.
Hearing: Rinne normally gives air conduction greater than bone conduction. Bone greater than air suggests conductive loss. Weber goes towards conductive loss, away from sensorineural loss; profound unilateral deafness can complicate interpretation.
A normal-looking disc does not exclude optic neuritis
Optic neuritis can cause reduced acuity, poor colour vision and pain on eye movement despite normal fundoscopy. Acute visual loss needs ophthalmic assessment, even after emotional stress.
Papilloedema is optic-disc swelling due to raised intracranial pressure. Headache, vomiting and transient visual obscurations may accompany it. A normal fundus does not exclude neurological disease.
14.4 Cognitive domains and lobar syndromes
Attention comes first. Someone with delirium may fail a memory task because they never registered the information.
Domain | Deficit | Example task |
|---|---|---|
Attention | Distractibility; difficulty holding/manipulating information | Months backwards, digit span |
Episodic memory | Poor new learning and delayed recall | Learn and later recall information |
Executive function | Poor planning, inhibition, switching or abstraction | Fluency, go/no-go, alternating sequences |
Language | Naming, comprehension, fluency or repetition impaired | Name objects, follow commands |
Visuospatial function | Poor spatial organisation or neglect | Clock drawing, figure copying |
Praxis | Cannot perform a learned act despite adequate basic movement | Demonstrate a familiar action |
Recognition | Cannot recognise familiar objects, faces or stimuli | Object/face recognition |
The useful localisation patterns are:
Frontal: disinhibition, apathy, perseveration, poor planning.
Dominant parietal: Gerstmann syndrome: agraphia, acalculia, finger agnosia and left–right disorientation.
Non-dominant parietal: neglect and poor awareness of a deficit.
Medial temporal: impaired new learning.
These are network clues, not rigid one-lobe rules. A low MMSE, MoCA or ACE score can reflect delirium, depression, sensory or language difficulties, education, medicines or dementia. A normal score does not exclude disease. Loss of independent function helps separate dementia from MCI, allowing for previous ability and physical disability.
14.5 Thyroid and other physical findings
State | Clinical picture | Typical blood pattern |
|---|---|---|
Overt primary hypothyroidism | Cold intolerance, constipation, weight gain, dry skin, fatigue, slowing, low mood; cognition may suffer | TSH ↑, free T4 ↓ |
Subclinical hypothyroidism | Often few symptoms | TSH ↑, free T4 normal |
Thyrotoxicosis | Heat intolerance, weight loss, tremor, tachycardia, anxiety, irritability | TSH ↓, free T4 and/or T3 ↑ |
Goitre means enlargement, not overactivity. Lithium-associated hypothyroidism can often be treated while lithium continues. Low free T4 with an inappropriately normal/low TSH suggests a different problem, such as central hypothyroidism or non-thyroidal illness. Acute illness can distort results.
Keep the physical differential open: chest pain can be cardiac despite anxiety. Fever and breathlessness on clozapine may be pneumonia, aspiration or myocarditis. Sedation and impaired swallowing increase aspiration risk; constipation with distension/vomiting is urgent.
14.6 ECG essentials
Standard settings: speed 25 mm/s, voltage 10 mm/mV. One small square = 40 ms; one large square = 200 ms. For a regular rhythm, rate ≈ 300 ÷ large squares between R waves. For an irregular rhythm, count QRS complexes over ten seconds and multiply by six.
Interval | Meaning | Number to know |
|---|---|---|
PR | Atrioventricular conduction | About 120–200 ms |
QRS | Ventricular depolarisation | ≥120 ms is broad |
QT | QRS onset to T-wave end | Varies with heart rate; use QTc |
Bazett: QT/√RR. Fridericia: QT/∛RR. Use seconds in both. Bazett can overestimate QTc during tachycardia, including clozapine-related tachycardia.
QTc: thresholds and what changes the risk
BHRS antipsychotic guidance uses 440 ms in men, 470 ms in women as action thresholds; 500 ms is a major concern requiring urgent review. Check the tracing, potassium, magnesium, calcium, other medicines, bradycardia and cardiac disease. Syncope/presyncope with significant prolongation needs urgent rhythm assessment.
Stopping/changing the culprit is often required, with specialist input. Clozapine is an exception to an automatic switch because abrupt substitution can cause severe relapse; obtain specialist assessment.
Pattern | Think of |
|---|---|
Independent P waves and QRS complexes | AV dissociation: possible complete heart block, but interpret rates and their relationship |
Irregularly irregular, no consistent P waves | Atrial fibrillation; assess rate and thromboembolic risk |
Regional ST elevation in related leads | Possible acute coronary occlusion: assess as an emergency |
Widespread ST elevation + PR depression | Pericarditis in the right clinical setting |
Broad QRS after tricyclic overdose | Sodium-channel blockade and serious cardiotoxicity |
Peaked T waves/progressive conduction disturbance | Hyperkalaemia; check urgently |
A normal ECG does not exclude acute coronary syndrome or myocarditis. Lead positions: V1/V2 in the fourth intercostal spaces beside the sternum; V4 in the fifth at the midclavicular line; V3 between V2/V4; V5/V6 level with V4. Misplacement can mimic pathology.
14.7 Starvation, purging and substance-related signs
Starvation: bradycardia, hypotension, hypothermia, weakness, lanugo and oedema. Purging: dental erosion, parotid swelling, knuckle calluses and potassium depletion. Normal electrolytes do not prove stability. During refeeding, phosphate, potassium and magnesium can fall from normal baseline values. Weight trajectory, observations and function matter.
With alcohol, distinguish withdrawal (tremor, sweating, tachycardia), liver disease (jaundice, ascites, other stigmata), and neurological/nutritional damage. Asterixis is negative myoclonus seen in metabolic encephalopathy, not a specific sign of alcohol use. Confusion, ataxia or ocular signs with nutritional vulnerability suggest Wernicke encephalopathy.
Opioid withdrawal: dilated pupils, yawning, tears, rhinorrhoea, piloerection, aches, diarrhoea. Intoxication: sedation, respiratory depression, often small pupils. Fever, an infected injection site or a new murmur suggests infection, including endocarditis.
14.8 Know what an investigation can and cannot establish
Apparently reassuring result | What it does not exclude |
|---|---|
Normal FBC/inflammatory markers | Every medical cause of psychiatric symptoms |
Negative urine drug screen | Exposure outside the assay or detection window |
Normal routine EEG | Epilepsy |
Normal structural brain scan | Dementia or functional neurological disorder |
Choose tests to answer a clinical question. Electrolytes, renal function, calcium, glucose, thyroid tests and targeted nutritional/infection tests answer different questions. New focal signs, rapid cognitive decline, delirium, suspected toxicity and an atypical first presentation should keep the physical differential active.