In the cranial nerves, herpes zoster has a predilection for the fifth and seventh nerve. ‘Ophthalmic herpes’ is infection of the first division of the fifth nerve and may lead to corneal scarring and secondary panophthalmitis. ‘Geniculate herpes’ (the Ramsay Hunt syndrome, seep. 889) leads to facial palsy accompanied by vesicles on the pinna, external auditory meatus and fauces. The local complications of shingles are secondary bacterial infection, very rarely purpura and necrosis in the affected segment (‘purpura fulminans’), generalized herpes zoster, and postherpetic neuralgia.
A myelitis, meningo-encephalitis or motor radiculopathy may be caused by varicella zoster. Treatment with acyclovir is given (see p. 1015).
Postherpetic neuralgia Postherpetic neuralgia is pain in the zone of the previous eruption; it occurs in some 10% of patients (often elderly). It is a burning, continuous pain responding poorly to all analgesics. Depression is almost universal. Treatment is unsatisfactory but there is a trend towards gradual recovery over 2 years.
Tertiary neurological disease is now rare but a wide variety of syndromes still occur, particularly in those who may have had many sexual partners.
For practical purposes, negative sero ogical tests for syphilis in blood exclude the disease. The main syphilitic syndrome are described below. Asymptomatic neurosyphilis This is the term used to describe positive CSF serology without signs.
This presents as:
SUBACUTE MENINGITIS often with cranial nerve palsies and papilloedema
A FOCAL FORM (a gumma), is an expanding intracranial mass which causes epilepsy, raised pressure and focal deficits, e.g. hemiplegia
PARAPARESIS caused by a spinal meningovasculitis Tabes dorsalis
This is a complex syndrome in which demyelination occurs in the dorsal roots. Many of the features are due to ‘de-afferentation’. The elements of the syndrome are:
• Lightning pains
• Ataxia, loss of reflexes, widespread sensory loss andsome muscle wasting
• Neuropathic joints (Charcot’s joints)
• Argyll Robertson pupils
• Ptosis and optic atrophy
General paralysis of the insane (GPI)
The grandiose title indicates that this is a syndrome of madness and weakness. The dementia is often similar to that associated with Alzheimer’s disease (see p. 965). Progressive dementia, brisk reflexes, extensor plantar reflexes and tremor occur. Death follows within 3 years of the onset.
Argyll Robertson pupils are usually present. Seizures may occur.
Mixtures of the syndromes described above occur. In congenital neurosyphilis (acquired in utero), there are features of both tabes dorsalis and GPI in childhood; this is known as taboparesis.
In secondary syphilis, a self-limiting meningeal reaction occurs that may be symptomless or may cause a subacute meningitis.
Benzylpenicillin 1 g daily by injection for 10 days in primaryinfection eliminates the risk of future tertiary syphilis. Established neurological disease can be arrested but ot usually reversed with penicillin. Parenteral penicillin for 2-3 weeks is given for all forms of neurosyphilis. Allergic reactions (Jarisch-Herxheimer reactions) may occur; high-dose steroid cover is usually given with penicillin to reduce their severity.
AIDS AND THE NERVOUS SYSTEM
Individuals with HIV infection frequently present with ordevelop neurological disease. In addition, HIV-infected patients have a high rate of cerebrovascular disease. There is a variety of clinical neurological pictures, which may e confusing.
ACUTE ASEPTIC MENINGITIS. This is believed to be a primary HIV meningitis. Spontaneous recovery is usual. CHRONIC MENINGITIS. This may occur with HIV itself, fungi (e.g. Cryptococcus neoformans or Aspergillus), tuberculosis, Listeria monocytogenes, Escherichia coli or other organisms. Treatment is typically difficult and unsuccessful.
AIDS-DEMENTIA COMPLEX. This is a diffuse, progressive,usually fatal HIV -related dementia, sometimes associated with a cerebellar syndrome, thought to be due to a primary cerebral HIV infection.
ENCEPHALITIS. Cytomegalovirus, herpes simplex, Toxoplasma and other organisms cause a severe and often fatal encephalitis.
CNS LYMPHOMA AND PROGRESSIVE MULTIFOCAL LEUCOENCEPHALOPATHY. These are progressive late complications of HIV infection. They are usually fatal.
This occurs in AIDS in the following patterns.
ACUTE HIV TRANSVERSE MYELITIS. This is believed to be a primary HIV myelitis. Spontaneous recovery is usual.
MYELOPATHY DUE TO INFECTION, e.g. with herpes simplex or zoster, cytomegalovirus.
CNS LYMPHOMA. Lymphomatous masses cause cord compression or malignant meningitis.
Three patterns occur:
1 Mononeuropathy, e.g. a common peroneal nerve lesion
2 Mononeuritis multiplex
MANAGEMENT OF AIDS OTHER INFECTIONS
The nervous system is involved in many infective diseases. Rabies Rabies is transmitted to humans from infected animals via penetrating wounds. The rabies virus multiplies in the wound and migrates via the peripheral nerves and dorsal root ganglia to the eNS. A fatal encephalitis follows in
which, at autopsy, characteristic neuronal inclusion bodies (Negri bodies) are observed.
Tetanus may follow even a trivial wound. There is liberation of a powerful toxin that travels within motor nerves to reach the eNS, where it binds irreversibly with certain sialic acid-containing gangliosides. The toxin blocks inhibition of spinal reflexes, resulting in spasms.
Botulism. The paralytic symptoms of botulism are caused by a presynaptic block in neuromuscular transmission.
This produces a chronic radiculopathy. A paraparesis can occur.
In tuberculoid leprosy a mononeuritis multiplex is seen. The infected nerves become large and palpable as hard cords. The peripheral nerves are also affected in lepromatous leprosy.
Poliomyelitis (see p. 50)
In this condition there is invasion of the anterior horn cells by the pathogenic virus. Many infections are subclinical but in a minority there is serious paralytic disease involving the respiratory muscles and sometimes causing a bulbar palsy.
Other examples of infection involving the eNS are summarized in Table 18.45. See also individual viral infections.
Progressive rubella encephalitis Some 10 years after the primary infection there is rarely a progressive syndrome of mental impairment, fits, optic atrophy, cerebellar and pyramidal signs. There is evidence of local antibody production against rubella viral antigen within the CNS.
Subacute sclerosing panencephalitis (SSPE) The persistence of measles antigen in the CNS is believed to be the cause of this rare late sequel to measles infection. Progressive mental deterioration, fits, myoclonus
and pyramidal signs occur, usually in a child. Diagnosis is confirmd by demonstrating a high titre of measles antibody in the blood and CSF.
Creutzfeld-Iakob disease (CJD)
This is a slowly progressive dementia characterized pathologically by ‘spongiform encephalopathy’. It occurs worldwide and is transmitted by an agent resistant to many of the usual sterilization processes. This is an
example of a ‘prion’ (proteinaceous infectious particles) or ‘slow’ virus disease. Infection has been transmitted from post-mortem and surgical specimens and corneal grafts, and to the recipients of human growth hormone (which was obtained from human pituitary glandsremoved at autopsy). The pathology of CJD is very imilar to bovine spongiform encephalopathy of cattle. The condition has a long incubation period, sometimes up to several years. Death is almost invariable within 2years from the onset of symptoms.
This is a dementia and cerebellar ataxia occurring in thehighlands of New Guinea. It is believed to have been spread by ritual cannibalism. Spongiform change occursin the brain (very similar to that in CJD). This obscure condition is also believed to be transmitted by a slowVIrus.
Progressive multifocal leucoencephalopathy This is an opportunistic infection with the papovaviruses JC and SV-40 (and others) in patients who are immunocompromised. Multifocal demyelinating hemisphere lesions develop that contain virus particles. Death is usual
after several years.
This is a severe encephalitic illness, usually of children, accompanied by fatty infiltration of the liver and hypoglycaemia. A viral cause has been postulated but other factors, including aspirin therapy, have also been implicated. Mollaret’s meningitis
This term is used to describe recurrent episodes of ‘aseptic meningitis’ over many years. A viral cause is postulated. Some of these patients are helped by treatment with he mitotic poison colchicine. Vogt-Koyanagi-Harada syndrome This is a recurrent inflammatory disease of cells of neural crest origin, causing uveitis, meningo-encephalitis, vitiligo, deafness and alopecia.
ME: myalgic encephalomyelitis (epidemic neuromyasthenia) (see p. 963)
Headache, fever, lassitude, torpor, myalgia and depression sometimes follow viral infection (e.g. hepatitis, infectious mononucleosis, Coxsackie infections). It is paticularly difficult to distinguish between organic and psychological elements in these cases and there is wide variation of opinion about causation.
This condition may cause a chronic meningo-encephalitiswith sarcoid lesions within the brain and spinal cord, a peripheral neuropathy, cranial nerve palsies (particularly bilateral seventh nerve palsies) or, rarely, a myopathy.
The three principal features are recurrent oral and genital ulceration, inflammatory ocular disease and neurological syndromes. Brain stem and cord lesions, aseptic meningitis, encephalitis and cerebral venous thrombosis also occur.
ABSCESSES WITHIN THE NERVOUS SYSTEM
A focal area of infection within the cerebrum or cerebellum presents as an expanding mass lesion (see p. 932). The usual organisms are streptococci (aerobic, anaerobic and microaerophilic species), Bacteroides spp., staphylococci nd enterobacteria. Mixed infections are common. Fungi can also cause brain abscesses. Multiple abscesses may develop. A parameningeal (e.g. ear, nose, paranasal inus, skull fracture) or distant (e.g. lung, heart, abdomen) focus of infection may be present. Frequently no cause is found.
Tubercle bacilli cause chronic caseating intracranial granulomas-tuberculomas-which are the commonest single intracranial masses in areas such as India where tuberculosis is common. Tuberculomas either present as mass lesions or occur in the course of tuberculous meningitis.
They may also be symptomless and appear on skull X-rays as areas of intracranial calcification.
Headache, focal signs (e.g. hemiparesis, aphasia, hemianopia), epilepsy and raised intracranial pressure occur. Fever, leucocytosis and a raised ESR are usual in cerebral abscess but are not always present. The presentation may thus be remarkably similar to many cerebralneoplasms. The symptoms may be indolent, developing over we ks, particularly in the cerebral hemispheres. Cerebellar abscesses tend to develop more acutely.
Urgent CT or MRI scanning is essential. The search fora focus of infection should include a detailed examination of the skul l, ears and paranasal sinuses. Lumbar puncture is contraindicated in suspected brain abscess prior to scanning.
Treatment should be carried out with liaison between neurosurgeon and microbiologist. Surgical decompression may be necessary if antibiotics are unsuccessful. Despite treatment, the mortality of abscess remains high, at around 25%, and epilepsy is common in survivors.
This is usually secondary to local infection. The featuresare similar to those of a cerebral abscess. Intracranial epidural abscess
Rarely, a collection of pus tracks along the intracranial epidural space, causing sequential cranial nerve lesions, typically without evidence of raised pressure. There is usually evidence of local infection. Drainage is necessary Spinal epidural abscess Staphylococcus aureus is the usual organism responsible. It reaches the spine via the bloodstream, e.g. from a boil. There is fever and usually back pain followed by paraparesisor root lesions. Emergency myelography, decompression and antibiotics are indicated.