Neurology

Published on 24/06/2015 by admin

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Last modified 24/06/2015

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Common neurological conditions seen in the long case are stroke, multiple sclerosis, epilepsy and myasthenia gravis. Any one of these conditions can be the main problem of the case. But many other neurological conditions, such as Parkinson’s disease, other movement disorders, peripheral neuropathy, migraine, vertigo, tinnitus and myelopathy, can be present as an associated problem. It is important to look at the case as a whole when encountering these features, because another medical condition or a medication may be the causative factor of the neurological deficit. In such situations, treating the possible precipitating condition or changing the medication may resolve the neurological problem. An example is a patient with a background history of hepatitis C presenting with peripheral neuropathy. The neuropathy is sometimes caused by hepatitis C-associated cryoglobulinaemia. So it is important to contextualise the neurological symptoms and signs, in the interplay of multiple diseases and medications in the long case.

COGNITIVE IMPAIRMENT

It is unusual to encounter a significantly demented patient in the long case examination. However, there have been instances where patients with progressive dementia, but who could still hold a reasonably rational conversation, have been presented at the examination. The objective of such long cases is to assess the candidate’s ability to identify the problem of progressive intellectual deterioration and the candidate’s knowledge and skills in handling the issues involved, such as remedying any correctable causes, attempting to slow down the deterioration where possible, and preparing for the optimal care of the patient medically and socially in anticipation of the inevitable total dementia.

Approach to the patient

Candidates should be able to perform a very quick assessment of the patient’s cognitive function, and a formal ‘mini mental’ test is a useful tool for this. Because this is a standardised and quantitative test, it can provide an objective assessment (though not always very accurate) that would be acceptable to the examiners. A good method to employ here is to memorise the mnemonic, which incorporates the important components of the mini mental test:
The maximum score is 30. A score of < 25 may suggest dementia.
In addition to the above assessment, look for features that may give clues to possible intellectual impairment. General demeanor, the response to your initial introduction, smell of urine and extrapyramidal facies are some such important clues. Check for the frontal reflexes.

STROKE AND TRANSIENT ISCHAEMIC ATTACK

Approach to the patient

When approaching a stroke patient, the candidate should be well versed in the basic principles of stroke management.

History

In the young stroke patient, consider the possibility of patent foramen ovale and paradoxical embolus.
Also obtain history regarding other thrombotic events (DVT, PE, miscarriages) in the patient or first-degree family members. Ask about alcohol consumption and recent falls that may have caused an intracranial haemorrhage.
Enquire about premorbid as well as the current level of independence and mobility. If the patient is incapacitated, ask about the social support available at home. Ask about the patient’s mood.

Examination

Never forget to look for poorly controlled hypertension, fundoscopic changes of hypertension and diabetes, carotid bruits, orbital bruits (commonly heard in the side opposite the carotid occlusion, due to increased contralateral flow), atrial fibrillation, cardiac murmurs and evidence of peripheral vascular disease.
Check the blood pressure in both arms (a difference of more than 20 mmHg systolic may suggest subclavian stenosis and a steal phenomenon). Look for complications such as pressure sores, limb contractures and disuse atrophy of the weak limbs.
See whether the patient has a percutaneous gastrostomy (PEG) feeding tube inserted and, if present, inspect for cellulitis or pus around the insertion site. Check the patient’s temperature and look at the temperature chart for any evidence of fevers. Check for DVT in the lower limbs if a peripheral embolic cause is suspected, especially in the younger patient.
With the history and the physical examination, the candidate should be able to accurately characterise the exact neurological deficit and localise the area of the brain involved.

Management

Depending on the type and severity, transient ischaemic attack may be managed at home if timely investigation and adequate treatment can be arranged. Stroke with residual neurological deficit needs to be managed in hospital. Essential therapeutic goals in a stroke patient are early rehabilitation, the prevention of secondary complications such as DVT, aspiration pneumonia, urinary tract infections, limb contractures and pressure sores, prevention of recurrent stroke, and identifying/treating stroke risk factors. Rehabilitation should be planned according to the deficits identified on the examination.
Younger stroke patients (aged under 40 years) should be screened for unusual causes, such as illicit drug use (cocaine), vasculitic disorders, subacute bacterial endocarditis, patent foramen ovale or cardiac septal defects with a right-to-left shunt, paroxysmal atrial fibrillation or atrial flutter, thrombophilia, and inherited disorders such as CADASIL (see box) and homocystinuria. Some patients can develop a ‘post-stroke dementia’, and therefore the patient’s cognitive function should be assessed.

Investigations

The following investigations should be considered for the stroke patient, as guided by the clinical assessment:

1. Urine analysis and blood sugar levels—to exclude diabetes mellitus or a precipitating urinary tract infection

2. Full blood count—looking at haemoglobin levels (to exclude polycythaemia), white cell count (to exclude sepsis as a precipitating cause) and platelet count (rarely, essential thrombocythaemia can contribute to stroke)

3. Coagulation profile

4. ESR—to exclude any inflammatory arteritic/vasculitic process

5. Chest X-ray—for cardiomegaly/neoplasms/aspiration

7. Fasting blood lipid profile

8. CT or MRI of the head—looking for ischaemic infarcts, haemorrhage or mass lesions

9. Doppler scan of the carotid arteries—and, if the duplex ultrasonography suggests significant carotid stenosis, consider obtaining another confirmatory imaging study such as carotid CT angiography, carotid digital subtraction angiography or MR angiography. If the diagnosis is confirmed, discuss possibility of interventions such as carotid endarterectomy or stent placement in suitable patients.

10. If the patient is in AF, ask for the results of the transoesophageal echocardiogram (TOE)—looking for thrombus or spontaneous echo contrast in the left atrial appendage. This may also show up any atheromatous plaques in the ascending aorta and the arch of aorta that may have contributed to the stroke.

If there is evidence of right-to-left shunt, particularly when right-sided pressures become high (as in Valsalva manoeuvre), a follow-up TOE is indicated to better characterise this shunt with a view to closing it (Fig 5.2).

image

Figure 5.2 Percutaneous PFO closure using an Amplatzer PFO Occluder (left cranial oblique view). (A) The constrained Amplatzer PFO Occluder is advanced within the Amplatzer delivery sheath, which is positioned across the PFO in the left atrium. (B) The left atrial disc is deployed by withdrawing the delivery sheath and then gently pulling against the interatrial septum. (C) Further retention of the delivery sheath under tension of the left atrial disc against the interatrial septum allows for release of the right atrial disc. The device has reassumed its double disc shape connected by a thin waist passing across the PFO. (D) A right atrial contrast injection by hand through the delivery sheath opacifies the right side of the interatrial septum, confirming a correct position of the device. Note the nearly horizontal orientation of the Amplatzer PFO Occluder and the indentation of the septum by the lower part of the disc. This results from the tension of the delivery cable on the device. (E) Release of the device from its delivery cable by counter-clockwise rotation. The device assumes the more perpendicular position of the interatrial septum. (F) Control right atrial angiography by hand injection through the sheath delineating the right atrial septum and correct device position. The left atrial septum can be visualised during the levo-phase(reprinted from Adrouny Z A, Griswold H E 1963 Hemodynamics of mitral valve disease as altered by systemic hypertension. American Journal of Cardiology 11:3).