Neuropathology Flashcards
Role of CSF
Transport of metabolites
Cushions the brain and spinal cord
Immune regulation and defence
Auto regulation of blood flow to the brain
Circulation of CSF
[500ml a day circulates]
Lateral ventricle-[Foramen of Monro]—> Third ventricle
[Cerebral aqueduct]
Fourth ventricle–[Foramen of Luschka/ Magendie]–> Cisterna magna
Ascends over cerebellum and cerebral hemispher–[arachnoid granulation]–> Superior sagittal sinus
Ascends ventral subarachnoid space—> Over cerebral hemisphere—> arachnoid granulation…
Hydrocephalus Ex vacuo
Enlargement of ventricles and subarachnoid space due to shrinking of brain tissue.
Occurs in dementia
Raised intracranial pressure
- Definition
- Causes
CSF pressure above 200mm H2O
Causes:
- Hydrocephalus
- Intracranial space occupying lesion [neoplasm, bleed, abscess]
- Cerebral oedema [e.g in hypoxia, injury, trauma]
Consequence= herniation
Herniations
- Different types
Subfalcine
- Cingulate gyrus dispace under the free edge of the falx cerebri
Central/ transtentorial
- Cerebral hemisphere tissue pushed through tentorium cerebelli
Tonsillar/ cerebellar
- Cerebellar tissue pushed through foramen magnum
- Can compress the medulla and cause breathing and cardiac impairments.
Duret haemorrhages
Small linear bleeds in the midbrain and upper pons.
- Caused by tonsillar herniation—> compression in medulla oblongata
Examples of space occupying lesions
Haemorrhages:
- Extradural
- Subdural
- Subarachnoid
- Intracerebral
Oedema + haemorrhage [from ischemic infarct]
Neoplasm
Abscess
Vascular brain injury causes [include vessels involved]
- Extradural
- Subdural
- Subarachnoid
- Intraparenchymal
Extradural bleed
- Severe trauma with arterial laceration
- Middle meningeal artery
Subdural
- Trauma minor in atrophy
- Caused by ruptured vein [bridging vein]
- Seen in old age
Subarachnoid
- Rupture of saccular aneurysm in circle of willis
Intraparenchymal
- Bleeding into the brain, from BV inside the brain.
- Hypertension
Saccular aneurysm
Known as ‘berry aneurysm’
- Most common type of intracranial aneurysm
Can lead to subarachnoid haemorrhage if it ruptures
Vessels affected:
- Anterior communicating [40%, most common]
- Middle cerebral
- Internal carotid
- Tip of basilar
Cerebral oedema
- Causes
Vasogenic
- Increased vascular permeability
Cytotoxic
- Neuronal, glial/ endothelial cell damage
Global vs focal ischemia
Global- Includes wide range of brain tissue
- Hypoxia [low O2 in blood]
- Can still preserve brain if kept cold
Focal
- Localised to brain tissue
- Obstruction of blood flow
- More dangerous
Hemorrhagic vs ischemic cerebral infarction
Haemorrhagic
- Red blood cell in infarcted tissue
- Caused by emboli
- Petechial (small bleeds) lesions [ from bone marrow emboli]
Ischemic
- Lack of blood flow= infarction
- Caused by thrombosis
Histology of ischemic infarcts
ACUTE NEURONAL INJURY
Pyknosis [irreversible condensation of chromatin] in nucleus of neurones
Red neurones
Shrunken cell bodies
Loss of nucleoli
Eosinophilia [increased eosinophils] of cytoplasm
Glioma examples
Glioma- neoplasm of glial cells
Examples
- Astrocytoma
- Oligodendroglioma
- Glioblastoma [very malignant]
Neoplasm of the brain example
[25% are metastatic]
Gliomas
Ganglion cell tumours- neural tumours
Meningiomas
Medulloblastoma [poorly differentiated]
Primary CNS lymphona
Peripheral nerve tumours
Peripheral nerve tumours example
Schwanoma - Schwann cells
Neurofibroma [nerve cell tumour]
MPNST [malignant peripheral sheath tumour]
Encephalitis
Inflammation of the brain
Viral causes:
- Herpes simplex
- CMV
- HIV
Examples of parasitic infection of the brain
Toxoplasmosis
Cyscticerosis
-Localised infections
Spinocerebellar degenerative diseases
- Definition
- Symptoms
Accumulation of protein aggregates—> loss of cellular then CNS function
Symptoms:
- Dementia
- Personality changes
- Language disturbance
- Paralysis
- Movement distrubance
Prion disease
Progressive neurodegenerative condition
Example:
CJD [Creutzfeldt-Jakob]
Consequences of head trauma
Skull fracture
Contusion [bruise]
Laceration
Diffuse axonal injury [widespread lesion in white matter]
Vascular injury
Coup and contrecoup head injury
Coup- Injury of the brain occurs under the site of impact
- stationary head striking moving object.
Contrecoup
- Injury occurs in the opposite site of where head was hit.
- e.g moving head hitting a stationary object
Hydrocephalus
- Causes
- Clinical differences
Obstruction of CSF flow
Impaired arachnoid granulation absorption
Dementia- shrinking of brain tissue
Over production of CSF [rare]
Clinical classification
- Communicating [or obstructive]
- Non-communicating
Concussion
Clinical term used to describe symptoms associated head trauma
Spinal cord injury
C4 injury and above
- May paralyse the diaphragm [C3-5 innervation]
C4 injury below
- Quadriplegia
Thoracic spine injury
- Paraplegia
Berry aneurysm risk factors
- Lifestyle
- Acquired conditions
- Genetic
Lifestyle
- Hypetension
- Obesity
- Smoking
- Excessive alcohol
Acquired conditions
- Head trauma
- Infections
Genetics:
- Marfan’s syndrome
- Autosomal dominant polycystic kidney disease
- Ehlers-Danlos syndrome
- Inherited hemorrhagic telangiectasia
Extradural bleed
Haemorrhage between the periosteum and periosteal dura mater.
Causes:
- ARTERIAL laceration from severe head trauma
- Most likely of middle meningeal artery
Treatment of berry aneurysm
If ruptured
- Decrease intracranial pressure [i.e craniotomy]
- Restoration of respiration
Prevention of rupture
- Surgical clipping [craniotomy required]
- Endovascular coiling [endovascular approach, radiology]
Subdural haemorrhage
Haemorrhage between the meningeal dura layer and arachnoid layer.
Causes:
- Ruptured bridging vein
- Head trauma minor in atrophy
- Shaken baby syndrome
Risk factors:
- Old age [more brittle veins and larger subdural space]
- Infants [ larger subdural space]
- Blood thinners
- Dementia
- Long-term alcohol use
Subarachnoid bleed
Hematoma between the subarachnoid matter and pia mater [subarachnoid space]
Cause:
- Rupture of saccular aneurysm in the Circle of Willis
Intraparenchymal bleed
- Mechanism
- Causes [9]
Haemorrhage into the neural parenchyma
- Caused by rupture of small vessels within the brain
- Can be accompanied with oedema
Causes:
- Hypertension
- Sickle cell disease
- Arteriovenous malformation
- Amyloid deposits
- Intracranial neoplasm
- Coagulopathy
- Infection
- Vasculitis
- Trauma
Cauda equina syndrome
- Definition
- Symptoms [7]
- Causes [6]
Set of symptoms due to damage/compression of spinal cord below the cauda equina [end of spinal cord]
Symptoms:
- Severe back pain
- Saddle anesthesia
- Bladder and bowel dysfunction—-> decreased tone of the urinary and anal sphincters.
- Urinary retention—> Detrusor weaknesses
- Weakness of the muscles of the lower legs (often paraplegia)
- Sexual dysfunction
- Absent anal reflex
Cause:
- Disc herniation in the lower region of the back.
- Spinal stenosis
- Neoplasm
- Epidural abscess
- Epidural hematoma
- Trauma
Spine tumours
Primary
- Tumour originated in spinal tissue
Secondary
- Metastatic
- Originated from cancers, common to spread to bone
- Breast, thyroid, prostate, lung [bronchi], myeloma
Can compress spinal cord or spinal nerves
Spinal abscess
Caused by infection
- Can be caused by IV drug use
- Can destroy spinal disc
Bacterial
- S. aureus
- TB
- Meningitis
Fungal
Causative agent of meningitis in the elderly [4]
Streptococcus pneumoniae
Meningococcus
Listeria monocytogenes
Causative agent of meningitis in newborns
Escherichia coli
Group B streptococci
Causative agent of meningitis in children
Streptococcus pneumoniae
Meningococcus
Haemophilus
Viral causative agents of meningitis
HIV
HSV VZV
CMV
Enterovirus
Fungal causative agents of meningitis
Candida
Crytococcus neoformans
Histoplasma
Parasitic causative agents of meningitis
Angiostrongylus
Schistosoma,
Toxocariasis
Schistosoma
Cysticerosis
Signs and symptoms of meningitis
Stiff neck
Vomiting
Confusion
Photophobia
Butterfly rash- does not blanche under pressure.
Investigations for meningitis
Lumbar puncture [except when intracranial pressure is high, due to tonsillar herniation risk]
- Cloudy CSF
- Increased protein levels [viral]
- Increased WBC count [bacterial]
- Decreased glucose levels
CT/MRI done before lumbar puncture to check ICP.
Meningitis risk factors
IV drug use
Cerebral shunt
Cochlear implant
Young children- developmental abnormalities
Skull trauma, allowing nasal cavity bacteria to enter CSF space
Non-infections causative agents of meningitis [5]
Drug interactions:
- Antibiotics
- Immunoglobulins
- NSAIDs
Sarcoidosis
Malignant/metastatic
Lupus erythematosus
Vasculitis
Bacterial causative agents of meningitis for adults
Meningococcus [N.meningitides]
Step. pneumoniae
Causative agents for meningitis in the immunosuppressed
Meningococcus
Step. pneumoniae
Listeria monocytogenes
virus, TB, fungi
Risk factors for spinal S.aureus abscess [5]
Skin abcess
Septicaemia/ bacteraemia
Back injury/ trauma
Lumbar puncture
Surgery
Intraparenchymal haemorrhage risk factors [6]
Age, >60
Hypertension
System coagulopathies
Vuscular malformations
Vasculitis
Cerebral amyloid angiopathy
Complications of subarachnoid haemorrhage
Acute:
- Vasospasm= focal/global ischaemia
Late:
- Hydrocephalus due to scarring and CSF obstruction.
