Careers in clinical neurophysiology
Authors: David Allen
Publication date: 02 4월 2008
David Allen makes the case
Clinical neurophysiology is the branch of medicine concerned with recording and clinically interpreting electrical signals from the peripheral nerves, muscles, retina, brain, and spinal cord. It is a hospital based specialty that stimulates clinical and academic interests while allowing an excellent work-life balance.
The immediate appeal of the specialty is that of being able to solve, or advance greatly, neurological diagnostic puzzles, and it should attract doctors with an eye for detail but who can also see the bigger clinical picture.
Clinical neurophysiologists usually see patients at the key diagnostic stage of their illness. They give an opinion based on clinical findings and a clinical interpretation of neurophysiological studies. It may surprise many readers that consultant clinical neurophysiologists will typically spend one third of their working week in clinical consultations with patients, which is comparable to other physician specialties. We are not usually concerned with day to day inpatient management, which might appeal to some, but we are often asked to help guide management with respect to treatment decisions.
The specialty is small, with about 90 consultants and 30 trainees across the United Kingdom. Departments are found in some district general hospitals but are mostly in teaching hospitals or tertiary centres. Most doctors have little or no exposure to clinical neurophysiology at medical school or during their early postgraduate training. It is therefore not surprising that the specialty is often overlooked by those making career decisions and that it remains undersubscribed. Doctors deciding what career to follow, especially those interested in neurology or neurosciences, should consider the specialty and should not be put off by any preconceptions that they might have. Why not spend a day at your local department?
Although the subject can seem inaccessible or dry, once you acquire a basic understanding its relevance to daily clinical practice can be appreciated. It entails some technology, but nothing that would be a problem for today’s junior doctors.
The three core neurophysiological studies are electroencephalography, nerve conduction studies and electromyography, and evoked potentials. These assess the function of the nervous system at different levels and are not themselves disease specific. It is the pattern, distribution, and quality of the findings that, when interpreted in a clinical context, allow sometimes very specific electro-clinical correlations to be made.
Electroencephalography is the recording of brain activity; it is used mainly in the investigation and management of epilepsy. It provides evidence for its diagnosis and classification, which is helpful for decisions on treatment and prognosis. The electroencephalogram is also useful for investigation of other causes of cerebral dysfunction—for example, coma, encephalopathies, and Creutzfeldt-Jakob disease.
A clinical neurophysiologist will usually review the electroencephalogram on a computer and interpret it in the light of the clinical information provided. Although most departments now record simultaneous video during routine electroencephalography, in some instances they will want to assess the patient during the recording to elicit specific information essential to its interpretation—for example, during a seizure or coma.
Videotelemetry, long term electroencephalography with simultaneous video, is used for diagnosis or presurgical evaluation of patients with refractory focal epilepsy. Diagnostic questions might include:
Nocturnal attacks—frontal lobe epilepsy, parasomnia, or rapid eye movement sleep behaviour disorder?
Recurrent events with apparent loss of consciousness—epilepsy or non-epileptic attacks?
In presurgical evaluation, videotelemetry allows study of the seizure discharges on electroencephalography and the clinical semiology (seizure behaviour). Both can indicate where the seizures arise, often to a lobar or sublobar level, and hence identify a focal surgical target, even when magnetic resonance imaging might be normal. In some cases electrodes are inserted intracranially (by a neurosurgical colleague). This increases localisation precision and also allows other essential techniques, such as cortical stimulation, for brain mapping of eloquent cortex.
Nerve conduction studies and electromyography
Nerve conduction studies and electromyography entail the recording of muscle activity and nerve responses to electrical stimulation. The consultation is a dynamic, face to face clinical examination. Most clinical neurophysiologists take a history and perform a directed neurological examination before doing appropriate tests of the nerves and muscles. These test the differential diagnosis and aim to identify specific abnormalities to provide a diagnosis during the consultation. Good neurology knowledge and skills are required, alongside technical ability and a thorough understanding of the underlying physiology and anatomy. Electromyography clinics will appeal to those who enjoy physiology and like the diagnostic challenge of “short cases.”
As in other specialties, most patients are seen in outpatient clinics. An electromyography clinic might include patients with diverse neuromuscular diseases, such as carpal tunnel syndrome, ulnar neuropathies, motor neurone disease, myasthenia gravis, inherited polyneuropathy, acquired polyneuropathy, nerve injury or trauma, or muscle disease.
Evoked potentials record responses from both the peripheral and central nervous system in response to exogenous stimulation. These can assess the function of the spinal cord, brainstem, optic nerve, or retina. They are often used to provide evidence to support a diagnosis of multiple sclerosis. In the visual system they can localise lesions in the visual pathway (from photoreceptor cell to cortex). They can also reveal specific findings (for example, retinitis pigmentosa) when clinical examination and sometimes vision are normal.
Intraoperative monitoring entails continuous recording of evoked potentials during a surgical operation and aims to avoid iatrogenic accidental permanent damage to nervous tissue. Typically this is done to assess spinal cord function during orthopaedic or neurosurgical spinal operations.
A clinical neurophysiologist’s armoury includes a number of other investigations, procedures, and treatments: for example, electromyography guided botulinum toxin treatment for spasticity and dystonia; sleep studies; specialised electromyography techniques, such as single fibre electromyography; and transcranial magnetic stimulation and event related potentials, which can interrogate higher cortical function.
The specialty is outpatient based and consultant led, but with considerable support from clinical physiologists, who have a technical background, and other members of the department including secretarial, information technology staff, and healthcare assistants. In most departments clinical physiologists do almost all the electroencephalography and evoked potential recordings, and recently some have developed extended roles to include peripheral neurophysiology under medical supervision. The work is varied and includes a considerable amount of urgent inpatient, operating theatre, and intensive treatment unit work.
Clinical neurophysiologists don’t work in isolation but with other clinicians, particularly neurologists, paediatricians, orthopaedic surgeons, and neurosurgeons.
Many consultants develop a subspecialist interest, typically either neuromuscular disease or epilepsy. Some specialise in other areas such as movement disorders, botulinum toxin treatment, sleep, or visual electrophysiology. The pattern of referrals to neurophysiologists means that they gain considerable experience in epilepsy and neuromuscular diseases. They see a number of interesting and rare conditions, making their electro-clinical opinion valuable.
Work is mainly during office hours, and where an on-call service is provided it is largely as required by local arrangement and is light. Urgent electroencephalography may be requested for possible status epilepticus, coma of unknown cause, or encephalitis, and urgent electromyography may be required for patients with acute neuromuscular weakness. These patients are often in the intensive treatment unit, and the differential diagnosis includes Guillian-Barré syndrome, critical illness myopathy, myasthenia gravis, and motor neurone disease.
The specialty is suitable for those wanting to work part time and should appeal to anyone with a family and interests outside medicine.
Recruitment to clinical neurophysiology is after the foundation years and entails two years of core medical training at specialty training year 1 and year 2 levels, followed by entry at year 3 level into four years of specialty training. Membership of the Royal College of Physicians is required by the end of year 3, but applications from those with a paediatric background, with membership of the Royal College of Paediatrics and Child Health, are also encouraged, given that a considerable amount of electroencephalography and epilepsy work is paediatric. The four year training consists of one year of neurology and three of neurophysiology, with the opportunity to do some research and specialised training. With Modernising Medical Careers it is likely that dual accreditation with neurology will remain possible.
Unlike neuroimaging techniques, neurophysiology can detect, millisecond by millisecond, changes in function of the nervous system. It can interrogate or record the function of individual cells as well as that of integrated systems. In future, in addition to its already growing number of applications, clinical neurophysiology may well be used in the routine clinical assessment of cognitive dysfunction. It is also likely to become increasingly useful for guiding genetic testing—for example, in neuromuscular diseases, epilepsy, and retinal diseases—through electro-clinical correlations, at a time when genotype-phenotype correlations are often becoming more blurred.
The specialty should appeal to those with a breadth of medical knowledge but a desire to specialise, an interest in neurology, and good examination and information technology skills. It will be of particular appeal to those who are interested in epilepsy and neuromuscular diseases. It provides an excellent opportunity to develop clinical and academic interests while maintaining an excellent work-life balance with minimal on-call commitments and a predictable working day.
Typical consultant weekly timetable
Electromyography clinics (4-5 programmed activities (PAs))
Electroencephalography, evoked potentials, nerve conduction studies—reporting and clinical administration (3.5 PAs)
Additional specialist reporting or clinic (0-1 PAs)
Supporting professional activities (2.5 PAs)
Continuing professional development, audit, management, and approved external activities
I thank Richard Van der Star and Jonathan Cole for their helpful comments on the manuscript.
David Allen specialist registrar in clinical neurophysiology and chairman of the Association of Trainee Clinical Neurophysiologists