Download infectious diseasres of the nervous system

INFECTIOUS DISEASRES OF THE NERVOUS SYSTEM (Dr. E. Sobrevega)
Generalities:
1.
2.
3.
4.
5.
The CNS is well-protected from the outside environment
The CNS has poorly developed immune response
The infections may spread rapidly in the CNS via the CSF. The CSF serves as a good
medium for the spread of infections
CNS infection is more common than PNS infections
CNS infections are usually secondary
SOURCES of INFECTION:
5.
1. Via HEMATOGENOUS – most common
2. VIA CONTIGUITY OF STRUCTURES – e.g. Mastoiditis – brain abscess
3. DIRECT - - e.g. Penetrating injuries
4. CRANIAL & SPINAL NERVES
LYMPHATICS
INVOLVEMENT:
1.
2.
3.
4.
5.
SKULL – periosteum and sphenoid
MENINGES – arachnoid mater and subarachnoid space
BLOOD VESSELS – venous sinuses (Superior saggital, lateral, cavernous)
BRAIN PARENCHYMA
VENTRICLES
CNS INFECTIONS
1.
SKULL
 not commonly affected; some portions are potential sources of infection:
A. Piteous area
B. Sphenoid
C. Mastoid
2.
MENINGES
 most commonly affected in CNS infections
 Layers: (From outside to inside)
1.
2.
3.

Dura mater
Arachnoid mater Leptomeninges
Pia mater
Spaces:
1. Epidural – focal abscess may result from infection
2. Subdural – abscess or effusion may result
3.


Subarachnoid space
In CNS infections, arachnoid mater and sub arachnoid space are most often affected.
In Meningitis, leptomeninges are affected
3. BLOOD VESSELS
1. Arteritis – thrombosis ---infarction
2. Venous Sinus Thrombosis
 Superior sagittal;
 Cavernous
 Lateral
Manifestations are focal and depend on the site.
4. BRAIN PARENCYHMA
 Diffuse – encephalitis
 Focal/ localized – abscess or granuloma
 Brain Parenchyma – more commonly infected than spinal cord parenchyma
5. VENTRICLES
 contain CSF which may disseminate infection
 ventriculitis is usually a part of meningitis
TERMS:
 Meningitis
 Encephalitis
 Meningoencephalitis
 Encephalitis
 Ventriculitis
 Arachnoiditis
 Neuritis
 Myelitis
CNS INFECTIONS MAYBE:
1.
2.
Generalized – Encephalitis
Focal
 Abscess – usually temporal love and cerebellum
 Granuloma – schistosoma, TB, Syphilis
RELATIONS OF THE BOPDY TO CNS INFECTIONS:
1.
2.
3.
Inflammatory response – fever, chills, leucocytosis
Increased ICP
Other signs and symptomsMeningitis –with nuchal rigidity
Abscess – focal neurologic deficits
NEUROSYPHILIS

Treponema pallidum
Primary Infection
Secondary Stage (Latent neurosyphilis)
unapparent meningeal inflammation
Tertiary Neurosyphilis:
A.
-
MENINGOVASCULAR SYPHILIS
Basal meningitis
Syphilis spinal Arachnoiditis
Pachymeningits hypertrophic cervicals
Meningeal gumma
B. SYPHILITIC ARTERITIS
C. PARENCHYMATOUS NEUROSYPHILIS
C. – tabes dorsalis
general paralysis of the insane (Paretic dementia)
Syphilitic optic atrophy
Syphilitic deafness
D. CONGENITAL SYPHILIS
Relative Incidence of Various Forms of Neurosyphilis
Type of Neuro-syphilis
Asymptomatic
Tabetic
Paretic
Tabo-paretic
Vascular
Meningeal
8th Nerve
Optic Neuritis
Spinal Cord
Miscellaneous
TOTAL
No. of Cases
219
%
31
203
78
19
30
12
3
66
37
9
20
19
6
10
6
1
3
3
1
676
SYMTPOMS OF DEMENTIA PARALYTICA
100
EARLY STAGE
LATE STAGE
Irritability
Fatigability
Conduct slump
Personality changes
Headaches
Forgetfulness
Tremors
Impaired Memory
Defective Judgment
Depression or elation
lack of insight
confusion or disorientation
poorly systemized delusions
seizures
Transient Paralysis or aphasia
SIGNS OF DEMENTIA PARALYTICA
Common
1. Relaxed, expressionless facies
2. Tremors of facial & Lingual muscles
3. Dysarthria
4. Impairment of handwriting
5. Hyperactive DTR
RARE
1. Focal signs – hemiplegia, hemanopsia, etc.
2. Optic atrophy
3. Eye muscle palsies
4. Absent reflexes
5. Babinski toe signs
Symptoms & signs in TABETIC NEUROSPYHILIS
Symptoms
%
Signs
Laminating Pains
94
Ataxia
48
Bladder distention
Paresthesias
Gastric or visceral Crises
94
Visual Loss
Rectal incontinence
Deafness
55
75
Abnormal Pupils
42
Argyll-Robertson
33
24
Others
Reflexes Abn
(-) Ankle Jerks
64
16
14
7
(-) Knee Jerks
(-) Reflexes
Romberg’s Sign
81
11
18
%
Impotence
4
impaired sensation/vibratory 52
sense
Impaired vision
43
Impaired touch & pain
Optic atrophy
Ocular palsy
Charcot joints
13
20
10
7
TYPE
I. Asymptomatic
II.
A.
1.
2.
B.
CLINICAL SYMPTOMS
No symptoms/CSF Abnormal
PATHOLOGY
Various, chiefly
leptomeningitis, Arteritis
encephalitis
Increased ICP & Cranial
nerve palsies
Leptomeningits with
hydrocephalus degeneration
of CNS arteritis
Granuloma (Gumma)
Meningeal & Vascular
Cerebral Meningeal
Diffuse
Focal
Cerebral Vascular
Increased ICP and Focal
cerebral symptoms of slow
onset
Focal Cerebral Symptoms and
signs of sudden onset
C.
Spinal Meningeal &
Vascular
III. PARENCHYMATOUS
A. TABETIC
B.
PARETIC
Endarteritis with
encephalomalacia
Paresthesias, weakness,
atrophy sensory loss in
extremities and trunk
Admixture of endarteritis &
meningeal infiltration and
thickening with degeneration
of nerve roots and substance
of the cord—myelomalacia
Pains, parasthesias, crises,
ataxia, impairment of
papillary reflexes, loss of
DTR’s, impairment of
propioceptive sensation and
tropic changes
Leptomeningits and
degenerative changes in
posterior roots, dorsal
puniculi & in the brainstem
Personality changes,
convulsion & mental
deterioration, physical
deterioration in late stages.
Meningoencephalitis
Loss of vision, pallor or optic
discs
C. OPTIC ATROPHY
Chronic Viral Infections
“Slow Virus”
Leptomeningitis, atrophic
changes





Can be caused by:
conventional agents:
SSPE – subacute sclerosing encephalitis
PML – progressive multifocal encephalopathy
AIDS – acquired immunodeficiency syndrome
PRP – progressive rubella pancencephalitis
UNCONVENTIONAL AGENTS:
 Do not cause cytopathic changes in cell culture
 No virus like particles in electron microscope
 Difficult purify
 Resistant to ionizing radiation, ultraviolet exposure
 May not contain nucleic acid but may be compose only of proteins (prion)
“proteinaceous infectious particles)
 E.g.
KURU
CJD – Creutzfeldt – Jacob Disease
GSS- Gerstmann- Strausler- Scheinker Dse
FFI – Fatal Familial Insomnia

KURU
Progressive fatal Neurologic Disorder
Occurs exclusively among natives of New Guinea
Manifestations:
in coordination, truncal/ limb ataxia
involuntary movement (Myoclonus/ Chorea)
dementia
80 % are women
principal mode of transmission: Cannibals
Pathology: Widespread Neuronal Loss:
 Neuronal/ Astrocytic Vacuolization
 Changes most prominent in cerebellum
CREUTZFELDT-JAKOB DISEASE
progressive disease of the cortex, basal ganglia and spinal cord
middle aged and elderly adults
spastic pseudo sclerosis
cortico- striato-spinal degeneration
gradual onset of dementia
Pyramidal Tract disease
Extrapyramudal tract disease
Myoclonus
CSF Normal
-
EEG periodic complexes of spike or slow wave activity with intervals of 0.5 to 2
seconds
CT scan – cerebral atrophy (Late in the course)
NO SPECIFIC TREATMENT
SSPE (SUBACUTE SCLEROSING PANCENCEPHALITIS)
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
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
Dawson’s disease
Sub acute inclusion body encephalitis
Caused by defective measles virus (M protein)
Presence of Type A intranuclear inclusions
Children younger than 12 years are predominantly affected.
Boys are more often affected than girls
5 to 10 SSPE cases/ 1 million clinical measles
SYMPTOMS:
gradual onset with out fever
forgetfulness
inability to keep up with school work
incoordination ataxia
myoclonic jerks; aphraxia, aphasia
rigid quadriplegia
CSF = Normal pressure, increased levels of measles antibody, oligoclonal bands
EEG = “Burst suppression” pattern
CT SCAN = cortical atrophy and focal Multifocal LOW-density lesions of the white matter
Course is prolonged
 NO DEFINITVE SPECIFIC THERAPY
PML (Progressive Multifocal Leukoencephalopathy)
 Sub acute demyelinating disease
 Caused by papova virus
 Occurs in patients with defective cell mediated immunity (Lymphoma, leukemia)
 Carcinomas, immunosuppresed patients
PATHOLOGY: Multiple/ Confluent areas of demyelineation; perivascular infiltration
EM Shows: papova particles
JC stains; SV – 40
SIGNS & SYMPTOMS:
 Onset is sub acute to chronic
 Focal or Multifocal hemiplegia, secondary to abnormalities, cranial nerve palsies
 Dementia
CSF = Normal
EEG = diffuse slowing
CT SCAN = non enhancing multiple lucencies in the white matter
ECEPHALITIS LETHARGICA (1917-1928)
 Sleeping sickness
 Von economo’s disease
 Acute/subacute onset: FEVER, HEADACHE, LETHARGY, EXTRAPYRAMIDAL Sxs
BACTERIAL TOXINS:
Corynebacterium diphteriae – exotoxin has predilection for sensory and motor nerves
(Peripheral nerves) and cranial nerves
TETANUS (Lockjaw)
 Clostridium tetani
 Localized/ generalized spasm of muscle die to the toxin which travels through the
blood and the peripheral connective tissue
 TETANOSPASMIN TOXIN acts on the muscles/ motor nerve endings as well as on the
spinal cord and brainstem.
 Incubation Period – 5-10 days
 Trismus
 Risus sardonicus
 No pathologic changes in CNS/PNS
 No specific changes in blood, urine
 Mortality rate is > 50%
 Death is due to: Paralysis of respiration
TREATMENT:
HTIG: 3000-6000 units IM
Tetanus toxoid: active immunization
Pen G
Sedatives, muscle relaxants
Anticonvulsants
Tracheoctomy for adequate hyperventilation
BOTULISM
 CLOSTRIDUM BOTULINUM
-
Botulinum toxin impairs release of acetylcholine at all peripheral synapses with resultant
weakness of striated and smooth muscles
 caused by toxin ingested after being produced in inadequately sterilized canned foods
 serotypes A * B – vegetables/ meat
 E – Fish/ marine mammal products
 Thermolabiles
 Symptoms appear 12-48 hours after ingestion of contaminated food
 Diagnosis: contaminated food examined, other family members also affected
 PROGNOSIS: depends on amount of toxins absorbed from the Gut
 DEATH: circulatory failure
Respiratory paralysis
Development of pulmonary complications
TREATMENT: Botulinum antitoxin – 20,000 – 40,000 UNITS
LEPROSY (Hansen’s disease)
 Mycobacterium leprae
 Predilection for skin and peripheral nerves
 Transmitted by direct contact
 Portal of entry is through abrasions in the skin/mucous membranes
 TYPES:
LEPROMATOUS – predominantly cutaneous
TUBERCULOID – predominately neural
 Commonly affected nerves, ulnar, auricular, posterior tibial, common peroneal, CN 5 & 7
DIAGNOSIS: Cutaneous nerve biopsy (sural)
TREATMENT: Dapsone (DBS-4, 4, diamino-diphossulfone)
PARASTITC INFECTIONS:
TRICINOSIS (TRICHINELLOSIS)
 Caused by roundworm – Trichinella spiralis
 Acquired by eating larvae (In cyst) in raw or undercooked pork
 PATHOLOGY: filiform larvae in cerebral capillaries, perivascular inflammation,
granulomatous nodules
 SxS: Fever, headache, muscle pains and tenderness , periorbital edema, subconjunctival
hemorrhage, confusion, seizures focal damage to the cerebrum, brainstem, cerebellum
DIAGNOSIS:
 Blood Exams - = increased muscle enzymes, eosinophilia
 Biopsy of muscle/ serologic tests
 TREATMEMT: THiabendazole to kill intestinal worms
Mebendazole to treat tissue larvae
SCHISTOMIASIS (Bilharziasis)
 S. Japonicum – most common
 Presence of OVA in the nervous System
 Inflammatory exudates containing EOSINOPHILS and GIANT CELLS (Granuloma)
Sxs: Granuloma may stimulate tumor (Increased ICP, focal deficits)
FOCAL SEIZURES
TREATMENT: PRAZIQUANTEL
ECHINOCOCCUS (HYDATID CYST)
 Tissue infection of humans caused by larvae of echinoccocus granulosus (tapeworm
parasite of DOG family)
 Brain involved in 2 %
 Cerebral cysts are usually single
 Most common in cerebral hemispheres
TREAMENT: Surgical Removal without puncturing the cyst
Albendazole or Mebendazole may decrease size of cyst
CYSTERCOSIS
 result of encystment of the larvae of Taenia solium, the pork tapeworm
 PATHOLOGY: cyst may be discrete and encapsulated and multicystic; military form is
common in children.

-
CLINICAL MANIFESTATIONS:
parenchymal, meningitis, intraventricular spinal

TREATMENT: ventricular shunting fir hydrocyst forms
Anti-convulsants for seizures
Praziquantel
Albendazole
MALARIA
 most common human parasitic disease
 transmitted by mosquitoes
 nervous system involvement = 2% of affected patients
 malignant tertian forma caused by Plasmodium falciparum
Neurologic Sxs due to:
congestion or occlusion of capillaries and venules with pigment laden, parasitize RBC and
to the presence of multiple petechial hemorrhages


Mortality rate: 20-40%
Treatment: Chloroquine
quinine,
pyrimethamine sulfadoxine (fansidar)
Tetracycline/clindamycin
TRYPANOSOMIASIS:
 Sleeping sickness




T. brucei, T. Cruzi (Chagas disease)
Transmitted by tsetse fly
PATHOLOGY: meningoencephalitis
TREAMENT:
Melaroprol
Nifurtimox
Maira’03