Neurologist Dr Giles Elrington offers advice on some trickier aspects of referring neurological conditions
Conditions that we think of as being neurological include a wide range of aetiologies, and a referral to neurology is not necessarily the most appropriate. Clinicians – and this is especially true of GPs – tend to see symptoms rather than diagnoses, so this article will consider them separately.
Symptoms
Headache
This accounts for 25-33% of all neurological referrals. Though it can be disabling, headache is almost always benign. Exceptions are thunderclap headache, which raises the possibility of subarachnoid haemorrhage and so belongs in the emergency department, and people with known cancer that spreads to the brain. Always consider erythrocyte sedimentation rate (ESR) or CRP in people over 50 with new headache to help rule out temporal arteritis – refer according to local protocols.
When headache is accompanied by other neurological problems, such as epilepsy or loss of function, it is those other problems – not the headache itself – that require investigation.
Some 40% of headache referrals in the neurology clinic are diagnosed as medication overuse headache (MOH) – something under-recognised in primary care. Much of the offending medication is purchased over the counter, so prescription data can be misleading. Feel free to refer these patients to the neurology clinic, but first consider MOH.
Brain scans are not indicated for the majority of people with headache, but many patients seem to think they've been referred for a scan. Refer directly for a scan if you think the patient needs one. But some PCTs don't allow this for headache patients, and for good reason. As well as the radiation risk, it overlooks many serious pathologies, giving a false sense of security.
MRI is safer and overlooks little, but it finds abnormalities in many healthy people, and these are known as ‘incidentalomas'. One in four healthy 20-year-olds has an brain MRI which is ‘not strictly normal'. Of those aged 75-97 who are asymptomatic, 18% have unsuspected stroke, 1.6% have a meningioma and 1.6% have an aneurysm on MRI.
Transient loss of consciousness
This accounts for about 25% of neurological referrals. The differential diagnosis is epilepsy, syncope, cardiac arrhythmia, psychosocial issues and, rarely, metabolic causes. All can result in a ‘convulsion', which is easily mistaken for epilepsy. The referral choice is between cardiology and neurology, depending on the available clues.
In the neurology clinic, the key diagnostic test is the witness account. This is best obtained face-to-face, so the witness should be invited to attend with the patient, or at least be available on the telephone at the time of the consultation. Written accounts are usually unhelpful.
Dizziness
This non-specific symptom needs clarifying, so ask patient to describe the symptoms without using the word ‘dizzy'.
In episodic true vertigo the patient experiences an illusion of movement, usually spinning, which often begins with an acute severe episode including vomiting. This is usually an inner-ear problem and is normally managed by ENT specialists together with physiotherapists.
Ataxia and other impairments of gait and balance can usually be detected from a careful history and examination. Sudden onset implies cerebrovascular disease (CVD), which may require urgent referral to the stroke team. Subacute or gradual onset ataxia has a neurological differential diagnosis and requires a neurological opinion, with urgency proportional to the speed of onset and examination findings.
A feeling of imbalance, such as ‘I feel I will fall, but haven't actually done so yet' or ‘I feel pulled to one side while walking', with normal examination, does not need referral or treatment, though concern about serious cause may trigger a neurological referral.
Weakness
Objective findings and the speed of onset are key. Abrupt onset of lateralised weakness raises the possibility of stroke, for which urgent intervention by the stroke team may be indicated. Gradual onset with objective abnormality on examination requires neurological referral, with urgency determined by speed of onset and clinical examination. Try to distinguish weakness from fatigue or tiredness, which rarely have a neurological cause. All organic neurological weakness has a specific pattern, such as pyramidal, proximal, distal, and radicular.
Sensory change
Sensory symptoms with no loss of function and normal neurological examination are unlikely to have a serious cause.
Numb feet with diminished reflexes is usually neuropathic, the most common causes being diabetes and alcohol dependence. A numb hand, particularly if it wakes the patient from sleep, is likely to be carpal tunnel syndrome – properly the remit of the orthopaedic surgeon or rheumatologist.
Sensory change in the face or head quite often remains undiagnosed. Neurological opinion for unexplained sensory change is certainly reasonable, but rarely needs to be urgent.
Memory difficulty
Memory clinics are set up to assess suspected Alzheimer's and vascular dementias.
The differential diagnosis of other cognitive dysfunction may be better addressed in a neurology clinic, though this differential commonly includes mood disorder, for which psychiatric referral may be appropriate.
Genuine concern about cognitive problems requires a witness history – obviously, a person with a poor memory may forget important matters. You should plan for this when making the referral.
Vision
The referral choice for visual symptoms lies between neurology, ophthalmology and, rarely, endocrinology. Bear in mind that ophthalmologists are usually more accessible than neurologists.
Double vision is more often neurological than ophthalmic. Binocular diplopia (cover an eye and the symptom vanishes) is neurological until proven otherwise.
Loss of vision may be neurological or ophthalmic. Visual field loss in both eyes is neurological. So too is optic neuritis, which presents with painful monocular visual loss, though it can mimic chiasmal (pituitary) mass lesions. Abrupt, transient, painless monocular visual loss – amaurosis fugax – is a form of TIA and should be managed as such, though the prognosis is better than for other TIAs.
Migraine visual aura is normally easily recognised, though if definitely monocular, can be confused with retinal detachment. Formed visual hallucinations are largely neurological. They occur in toxic confusional states and in Lewy body disease associated with Parkinson's disease.
It's not always obvious whether the cause of head pain is primarily ophthalmic, or attributable to some other system. If the symptom lasts more than a day, it is not caused by eye disease – unless the eye is red.
Facial pain and sensory change
This hardly ever ‘belongs' to ENT, the exception being craniofacial cancers that give objective trigeminal and other cranial nerve impairment. Chronic facial pain has the same causes as other cranial pain – it is not caused by chronic sinusitis. In general, facial pain should be managed by the same team who deal with headache. But, referral choice depends on local interest – some ENT, maxillofacial and dental surgeons have an interest here.
Diagnoses
Epilepsy
When seizures continue despite epilepsy treatment, the chance of the diagnosis being wrong is 20-33%, especially when there is psychosocial dysfunction – such as psychopathy. Beware of patients with ‘known epilepsy' – known to whom? On what evidence? Patients should be referred to a specialist, ideally an expert in epilepsy. Whoever reviews the diagnosis needs to see the evidence for the original diagnosis, which often proves to be presumptive, not evidence-based. Convulsions in pubs, clubs and aeroplanes, or on micturition, are usually convulsive syncope, not epilepsy.
Multiple sclerosis
When multiple sclerosis (MS) has been diagnosed it is easy to assume that new problems must be related to it. MS relapse may require steroid treatment, or review
of disease-modifying drugs. Before referring, rule out infection, particularly urinary or viral. Most large centres have MS specialist nurses who are an easier first contact than a neurologist. If the problem involves the bladder, the continence team or a urologist may be more help than a neurologist.
TIA and stroke
It is easy to overdiagnose CVD. A common mistake is to assume that cerebrovascular change on MRI, or stenosis on angiography, proves a diagnosis of CVD. Recurrent TIAs are often migrainous aura or partial epilepsy in reality. Clarifying the diagnosis may well require neurological referral.
Parkinson's disease
This is always a provisional diagnosis as there is never any proof without autopsy – so keep an open mind about patients with Parkinson's disease. It is often hard to know whether problems are caused by too much, too little, or the wrong sort of medication. A specialist nurse is often the first contact – they may work with a neurologist or they may work with an elderly care physician, many of whom know more than some neurologists.
Bell's palsy
This is usually managed appropriately in primary care. Sometimes specialists get overly concerned about serious disease, leading to unnecessary imaging and overtreatment. Alternative diagnoses can usually be excluded with a simple examination. A short course of steroids may be offered if the diagnosis is made early, but antivirals are not normally needed. Ophthalmic opinion is indicated if there is risk of corneal damage – beware of red eye in Bell's palsy.
Medically unexplained symptoms (MUS)
One in three people referred to neurologists has no neurological diagnosis. The MUS label helps as it doesn't assume that what is not explained by pathology or physiology is psychological.
In making a neurological referral for possible MUS, it is helpful to know which specialists and what tests the patient has already had. These patients can be demanding, so it is sometimes reasonable to ask a hospital doctor to carry the burden of supporting and containing the patients' needs for a while, to ease the strain in primary care – but we should try to avoid repeated rounds of re-investigation. It is helpful to be open about the referral agenda. Despite a psychiatric differential diagnosis for MUS, it is easy to offend with such a suggestion.
Special cases
Sometimes, patients' circumstances – such as family history or learning disabilities – can affect how you refer them.
Learning disability
Though caused by neurological disease, this is often managed by psychiatrists. All new referrals must state that the person is learning disabled, noting whether their disability is mild, moderate or severe. The key question is whether the patient is competent to make decisions. If not, this needs to be very clearly stated and the patient must always be accompanied to clinic by the person who normally makes those decisions.
The usual reason for neurological referral in these patients is difficult epilepsy. Early onset dementia, particularly in those with Down's syndrome, is another common reason.
In epilepsy, remember that treatment goals may be changed by the patient's inability to drive or work, or if they become pregnant. It is often better to limit anticonvulsant toxicity, to which the learning disabled are vulnerable, than to attempt seizure abolition.
Nursing and care home residents
The home needs to be advised to plan carefully for the consultation – it is all too easy to send the patient along with the least valuable team member, who is least likely to be able to give an account of the patient's difficulties, care needs and medication. Written handover is valuable.
Family history and genetics
It is easy to omit the objective data on the family history with the referral, relying instead on hearsay. Assemble background data before referral as there is rarely any hurry. If there is a family diagnosis, such as Huntington's disease, asymptomatic at-risk people may need referral to a geneticist – the exception is if the patient has a strong family history of berry aneurysm.
Brain tumours do not run in families, unless there is neurofibromatosis or von Hippel-Lindau disease. While MS shows some familial clustering, screening of family members is not indicated.
Newly registered patients
‘This patient has just registered. He was under his local neurologist and needs urgent review. We don't yet have his notes, but would you take over his care?' Step one is not to refer, but to ask the patient where they were seen and contact the previous hospital for their data. Then decide whether a new referral is indicated.
New referrals and second opinions
Primary care has the advantage of background knowledge – don't forget this in the referral letter. Consultation frequency is often more informative than a list of diagnoses. Results of tests are best detailed rather than, for example, stating ‘routine blood tests'. When asking for a fresh opinion, please provide the old evidence with the referral.
Dr Giles Elrington is a consultant neurologist at Bart's and The London NHS Trust, London
A short course of steroids may be offered if Bell's palsy is diagnosed early Bell's palsy
