Neurosurgery

HYDROCEPHALUS

Definition:
Hydrocephalus is defined as abnormal accumulation of cerebrospinal fluid (CSF) within the ventricles and subarachnoid spaces. It is often associated with dilatation of the ventricular system and increased intracranial pressure (ICP).

Physiology and circulation of CSF

The normal volume of circulating CSF is about 150 ml. The daily production of the CSF is about 450 ml, so the CSF volume is replaced approximately three times daily. CSF is produced by an active process independent of inracranial pressure (ICP). 80% of CSF is produced by the choroid plexus, and the rest is from the parenchyma

Functions of the CSF

1. Protect and support the brain and spinal cord. 2. Maintain homeostasis by acting as a transport medium for transmitters and as a method of removing the end-products of metabolism.

CSF Circulation

lateral ventricles. foramen of Monro third ventricle aqueduct of Sylvius fourth ventricle two foramina of Luschka foramen of Magendie subarachnoid space arachnoid villi venous blood blood stream.

CSF Circulation

CSF Circulation

CSF Circulation

Classification of Hydrocephalus
A. Non-communicating hydrocephalus (Obstructive): results from lesions that obstruct the CSF pathways from the lateral ventricles to the fourth ventricle. B. Communicating hydrocephalus: refers to circumstances in which the intracerebral CSF pathways are patent but there is accumulation of CSF, usually due to impaired CSF absorption.

Epidemiology of Hydrocephalus

The incidence of infantile hydrocephalus is about 3 to 4 per 1000 live birth

Aetiologty of Hydrocephalus

In patients with hydrocephalus, an imbalance has occurred between the normal physiological production of CSF and its absorption. This imbalance can be as a result of overproduction of CSF, an obstruction, or impaired absorption.

Normal Lateral Ventricle Vs Hydrocephalus

Normal Ventricles Vs Hydrocephalus

Normal Brain Vs Hydrocephaluscoronal section

Normal Brain Vs Hydrocephalus

Aetiologty of Hydrocephalus
A. Non-communicating hydrocephalus (Obstructive): 1. Lateral ventricle obstruction by tumours, e.g. basal ganglia glioma, thalamic glioma. 2. Third ventricular obstruction, due to colloid cyst of the 3rd ventricle or glioma of the 3rd ventricle 3.Occlusion of the aqueduct of Sylvius (either primary stenosis or secondary to a tumour) 4. Forth ventricular obstruction due to posterior fossa tumour, e.g. medulloblastoma, ependymoma, acoustic neuroma.

Aetiologty of Hydrocephalus

Communicating hydrocephalus: 1. Failure of absorption of CSF through the arachnoid granulations over the cerebral hemispheres. Sclerosis or scarring of the arachnoid granulations can occur after meningitis (bacterial or tuberculous), subarachnoid haemorrhage (either spontaneous, traumatic or postoperative), or trauma. 2. Oversecretion of CSF (choroid plexus papilloma).

Clinical Features of Hydrocephalus

Neonatal Hydrocephalus (Infantile): Failure to thrive and feeding problems. Enlargement of the head with increasing head circumference. Craniofacial disproportion with expansion of the dome and "low set" ears and eyes. The scalp is thin and glistening. The veins of the scalp are distended. The anterior fontanelle is enlarged, tense, and bulging.

Clinical Features of Hydrocephalus

Neonatal Hydrocephalus (Infantile): 7. Weakness of upward gaze (the setting-sun sign)(3rd ventricular pressure on midbrain tectum). 8. Diastasis of the cranial sutures. 9. Transillumination of the head is usually positive (if cortical mantle is less than 1cm and the patient is under 9 months age). 10. Bradycardia can be seen in extreme cases.

Neonatal Hydrocephalus (Infantile)

Neonatal Hydrocephalus (Infantile)

Neonatal Hydrocephalus (Infantile)

Neonatal Hydrocephalus (Infantile)

Neonatal Hydrocephalus (Infantile)

Clinical Features of Hydrocephalus
Hydrocephalus in older children and adults: Headache. Nausea and vomiting. Deterioration in the level of consciousness. May be associated ataxia. Visual disturbance.

Investigations of Hydrocephalus

A. Skull x-ray: can show 1. Separation of sutures. 2. Features of increased intracranial pressure

Investigations of Hydrocephalus

B. Ultrasound of the brain: can be done through opened anterior fontanelle to see the ventricular system.

Ultrasound of the brain

Investigations of Hydrocephalus
C. CT scan of the Brain: Ventricular dilatation. Can show the cause of obstruction as tumour. D. MRI of the brain: same as CT but no radiation so can be used for follow up.

CT scan of the Brain

CT scan of the Brain

Choroid Plexus Papilloma with Hydrocephalus

Third Ventricle Tumour with Hydrocephalus

MRI HYDROCEPHALUS

MRI Hydrocephalus

Investigations of Hydrocephalus
E. Lumbar puncture: can be done in communicating hydrocephalus for both diagnostic and therapeutic aims.

Management of Hydrocephalus

A. Medical management B. Surgical management

Medical management of Hydrocephalus

By using methods to reduce CSF production, but till now no definite medical treatment is satisfactory.

B. Surgical management

Removal of obstructing lesion e.g. removal of tumour will resolve hydrocephalus. Bypassing obstruction: either by: Endoscopic third ventriculostomy External drainage of CSF Internal diversion (Shunting)

Endoscopic Third Ventriculostomy

Endoscopic Third Ventriculostomy

Types of Internal Shunts
Ventriculo-Peritoneal Shunts. Ventriculo-Atrial Shunts. Ventriculo-Pleural Shunts.

Ventriculo-peritoneal Shunt

Shunted Hydrocephalus

The complications of shunting

Shunt obstruction: Shunt infection. Intracranial haemorrhage either: Intracerebral haemorrhage, or Subdural haematoma.

Complications of Ventriculo-Atrial Shunts

Infective Endocarditis. Volume Overload (Heart Failure). Arrhythmias (SA node).

Complications of Ventriculopleural Shunts:

Pneumothorax and Haemopneumothorax. Pleural Effusion. Pleural Empyema.


Benign intracranial hypertension
Benign intracranial hypertension, also known as pseudotumour cerebri, is, as its name implies, a disease of raised intracranial pressure, which usually runs a self-limiting course. Although termed ‘benign’, this condition can cause blindness due to severe papilloedema. The pathogenesis is poorly understood. The condition usually occurs in obese females.

Aetiology

Hypoparathyroidism. Vitamin A excess (used to treat acne)Pernicious anaemia.Drug reaction—tetracycline, nalidixic acid, sulfamethoxazole, indomethacin, danazole, lithium carbonate, oral contraceptive steroids.A similar condition results from venous sinus thrombosis.

Clinical features:

• Headaches• Visual disturbance.The headaches have the features of raised intracranial pressure in that they are worse in the morning and exacerbated by straining, stooping and coughing.The visual problems result from:• Papilloedema• Secondary optic atrophy• Diplopia due to sixth cranial nerve palsy.

Investigations

The CT and/or MRI scan will show no cause for the papilloedema and the ventricles will often be smaller than usual. Digital subtraction cerebral angiography or magnetic resonance venography may be performed to exclude thrombosis of a venous sinus as the cause. If the CT scan or MRI shows no mass or lesion a lumbar puncture is usually performed; the pressure will be raised. CSF examination is normal in benign intracranial hypertension but biochemistry and cytological investigations should be performed to exclude underlying pathology.

Medical (Conservative) Treatment

Benign intracranial hypertension is usually a self-limiting disease and most cases respond to simple conservative treatment. The usual measures undertaken are: Conservative Treatment: Weight loss (the patients are usually obese). Stopping any medication that may have led to the disease, e.g. oral contraceptives, tetracycline. Diuretic therapy. Acetazolamide (reduces CSF production). If there is no improvement with the above measures, treatment with glycerol or steroids may be tried.

Surgical Treatment

The major indications for surgical treatment are:Persistent severe papilloedema despite conservative measuresFailing vision.Intractable headaches despite conservative measures.The surgical procedures that can be performed are:• Optic nerve sheath decompression• Lumboperitoneal shunt.

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