Wilkinson. Essential Neurology 2005

Fig. 15.6 CSF abnormalities in various CNS infections.

level is depressed are often required of medical, nursing and physiotherapy staff (see Fig. 11.7, p. 187).

Reason for the infection

In every patient with a CNS infection, the question must be asked ‘Why has this infection occurred in this patient?’. Such a question will detect imperfections of immunization, the presence of diabetes, a state of impaired immunity, a previously undetected site of access or source for infection, a personal contact accounting for the infection, or a visit to a part of the world where the infection is endemic. Such an enquiry is an essential part of the patient’s management.

Reye’s syndrome

In this condition, which occurs in young children, there is damage to the brain and liver in the wake of a viral infection (especially influenza and varicella). Treatment of the child’s infection with aspirin seems to increase the chances of developing Reye’s syndrome (so avoidance of the use of aspirin in young children has been recommended).

Vomiting is a common early persistent symptom, rapidly progressing to coma, seizures, bilateral neurological signs and evidence of raised intracranial pressure due to cerebral oedema.

The primary insult seems to involve mitochondrial function in both the brain and liver.Abnormal liver function is evident on investigation, with hypoglycaemia, which may clearly aggravate the brain lesion.

Post-streptococcal syndromes

The classic neurological sequel of Group A steptococcal sore throat is subacute chorea, sometimes accompanied by behavioural disturbance, termed Sydenham’s chorea or St Vitus’ dance. It is usually self-limiting, subsiding after a few weeks. It is now rare in the UK but remains common in some parts of the world such as South Africa (see p. 75).

A different post-streptococcal syndrome is now seen more often in the UK, where the movement disorder is dominated by tics or sometimes parkinsonism, and does not always remit. Such cases can be indistinguishable from Gilles de la Tourette syndrome and post-encephalitic parkinsonism (encephalitis lethargica) respectively, and it is possible that an autoimmune response to streptococcus lies behind these conditions (see p. 76).

In all these conditions, positive streptococcal serology (raised antistreptolysin O or anti-DNAse B titres) points towards the diagnosis.

Chapter 3

Case 1

a.She has signs of a lesion in the left cerebellopontine angle, with ataxia, loss of the corneal reflex (cranial nerve 5) and deafness (cranial nerve 8). It has come on slowly, starting with deafness, so it is more likely to be an acoustic neuroma than a metastasis from her previous cancer.

An MR scan confirmed this. The neuroma was too large to treat with radiotherapy but was successfully removed, giving her a transient left facial weakness (cranial nerve 7) and permanent complete left deafness.

Case 2

a.It is hard to localize his symptoms to a single part of the brain. There are problems with memory (temporal lobes), behaviour and expressive language (frontal lobes) and spatial ability (parietal lobes). This could indicate a multifocal process such as metastases, a widespread diffuse process such as a glioma, or just possibly a focal tumour with hydrocephalus.

The drowsiness and papilloedema indicate raised intracranial pressure, making a degenerative disease or metabolic encephalopathy unlikely. There are pointers towards an underlying systemic disease in the weight loss and lymphadenopathy.

His CT brain scan showed widespread multifocal areas of high-density tissue in the white matter around the lateral ventricles. The appearances were typical of a primary CNS lymphoma. His HIV test was positive and his CD4 lymphocyte count was very low, indicating that the underlying disorder was AIDS. He continued to deteriorate despite steroids and highly active anti-retroviral therapy, and died 4 weeks later. The diagnosis of lymphoma was confirmed by autopsy.

Areas with a very high HIV prevalence, such as subSaharan Africa, are seeing a huge and increasing burden of neurological disease due to AIDS.

Chapter 4

Case 1

a.Your initial management plan would comprise:

•admission to hospital;

•half-hourly neurological observations recorded on a

Glasgow Coma Scale chart by competent staff, regardless of the boy’s location, e.g. A& E, ward, CT scanner etc.;

• urgent CT brain scan.

b.When he starts to deteriorate, you should obtain immediate neurosurgical advice and follow it.

The clinical situation strongly suggested a left-sided extradural haematoma which was confirmed by the CT scan and immediately drained in an emergency operation. Thankfully the boy made a full recovery from a potentially life-threatening situation.

Case 2

a.The point here is that you cannot simply assume that his coma is due to alcohol intoxication. People who abuse alcohol are very prone to head injury either through accidents or assaults. If they have a long-standing problem their clotting may be defective because of liver disease, increasing the risk of subdural, extradural and intracranial haemorrhage. They have an increased risk of epileptic seizures when intoxicated, when withdrawing from alcohol and as a consequence of previous head injuries, and he could be in a post-epileptic coma. Aseizure can cause a head injury. Alcohol abuse increases blood pressure and the risk of stroke. People with alcohol problems often neglect their health: he could be in a diabetic coma. He may be depressed and have taken an overdose. He might even have contracted meningitis in the back bar. Do not jump to conclusions when assessing an intoxicated patient.

Chapter 5

Case 1

a.She has clearly got parkinsonism, with gait disturbance, bradykinesia and rigidity. Parkinson’s disease is quite common at this age, but is not usually symmetrical like this. There are no additional neurological features to suggest a more complex neurodegenerative disease.

The vital part of the history is to establish what pills she is taking. The treatment for her gastro-oesophageal reflux turned out to be the dopamine antagonist metoclopramide. This was stopped and her drug-induced parkinsonism slowly resolved, although it was a year before she felt back to normal.

Case 2

a.This is a very difficult case. The main problem is cerebellar ataxia, with ataxia of gait accompanied by milder limb ataxia and cerebellar dysarthria. But the disease process is affecting several other systems: his optic nerves, causing optic atrophy; his spinal cord, giving extensor plantars; and his peripheral nerves, causing areflexia and impaired distal vibration sense.

b.This is a condition called Friedreich’s ataxia. It is a recessively inherited, early-onset form of multisystem degeneration that is classified under the term ‘spinocerebellar ataxia’. It is due to a trinucleotide expansion in the frataxin gene, which is believed to have a role in the function of mitochondria. It goes on to affect other systems of the body, causing cardiomyopathy or diabetes mellitus. It is very rare, except in clinical exams.

You may have considered the possibility of multiple sclerosis, which is a much commoner cause of cerebellar ataxia, optic atrophy and extensor plantars, but rare at this age, not usually gradually progressive and not affecting the peripheral nerves like this. If he was much older you would consider alcohol toxicity. This is a common cause of ataxia and peripheral neuropathy, but would not readily explain the optic atrophy or extensor plantars.

c.Clearly there are going to be a great many difficult matters to discuss with the patient and his family as they face the prospect of a progressive, disabling degenerative disease in early adult life. But there may be particular issues for the parents in relation to the genetics. Firstly, they may feel irrationally guilty that they have unknowingly each carried a genetic mutation that has contributed to their son’s illness. Secondly, they will have worries about his younger siblings, who each have a 25% risk of inheriting the illness too. The help of specialists in medical genetics is likely to be invaluable in helping them to approach these issues.

Chapter 6

Case 1

a.You should probably start by examining the patient yourself, but it is perfectly legitimate to say that if you are in doubt you should get advice from a more experienced colleague too.

The patient has a pattern of weakness that is typical of upper motor neurone weakness in the lower limbs, where the extensor muscles remain relatively strong and the hip

flexors, knee flexors and ankle dorsiflexors become weak. The extensor plantar responses also indicate an upper motor neurone problem. It often takes a few days before the reflexes become brisk when upper motor neurone weakness comes on acutely, so you should not worry that the reflexes are still normal here.

In other words, the problem is somewhere in the spinal cord. It is unlikely to be in the neck because the arms are not affected. You need an MR of the thoracic region, not the lumbosacral region, because the cord ends adjacent to the L1 vertebral body (Fig. 6.1).

The sensory signs may be very helpful in this situation. The patient felt pin-prick as blunt in his lower abdomen below his umbilicus and throughout both lower limbs. This is a T9 sensory level, indicating that the cord problem is at or above this dermatome. You call the radiologist back and ask for the appropriate scan. This shows a metastasis compressing the cord in the mid-thoracic region. His pain and neurological deficit improve with high-dose steroids and radiotherapy. Further investigation reveals several other bone metastases from prostate cancer. This is treated medically, with a useful period of palliation.

Case 2

a.The sensory symptoms on neck flexion (so-called L’Hermitte’s symptom) help to localize the problem to the neck. Urgency of micturition is also a helpful indicator of a problem in the spinal cord.

The signs are more specific, indicating pathology at the level of the 5th and 6th cervical vertebrae. He has the segmental sign of absent C5–6 biceps and supinator jerks, and tract signs below this level: brisk C7–8 triceps jerks and upper motor neurone signs in the lower limbs.

b.The most common pathology at this location in someone of this age is cervical spondylosis, with a C5–6 disc bulge and osteophyte formation compressing the cord. This turned out to be the cause here. There are several other rarer possibilities, including a neurofibroma. Because of his delicate manual occupation, he was keen to have decompressive surgery. This stopped his electric shocks and improved the sensation in his hands. The signs in his legs remained unchanged. His bladder symptoms persisted but responded to anticholinergic drugs.