Neuro surgery

 
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Fifth stage 

Neuro-Surgery

Lec-3 

د. عبدالرحمن 

2/5/2016 

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.  

 
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Classification of Hydrocephalus 

Non-communicating hydrocephalus (Obstructive):  

results from lesions that obstruct the CSF pathways from the lateral ventricles to the fourth 
ventricle. 

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.  

Aetiologty of Hydrocephalus 

Non-communicating  hydrocephalus (Obstructive): 

  Lateral ventricle obstruction by tumours, e.g. basal ganglia glioma, thalamic glioma. 
  Third ventricular obstruction, due to colloid cyst of the 3rd ventricle or glioma of the 

3rd ventricle 

 
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  Occlusion of the aqueduct of Sylvius (either primary stenosis or secondary to a 

tumour) 

  Forth ventricular obstruction due to posterior fossa tumour, e.g. medulloblastoma, 

ependymoma, acoustic neuroma. 

Communicating hydrocephalus: 

  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. 

  Oversecretion of CSF (choroid plexus papilloma). 

Clinical Features of Hydrocephalus 

Neonatal Hydrocephalus (Infantile): 

1.  Failure to thrive and feeding problems. 

2.  Enlargement of the head with increasing head circumference. 

3.  Craniofacial disproportion with expansion of the dome and "low set" ears and eyes. 

4.  The scalp is thin and glistening. 

5.  The veins of the scalp are distended. 

6.  The anterior fontanelle is enlarged, tense, and bulging. 

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. 

  Hydrocephalus in older children and adults: 

1.  Headache. 
2.  Nausea and vomiting. 
3.  Deterioration in the level of consciousness. 
4.  May be associated ataxia. 
5.  Visual disturbance.  

 
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Investigations of Hydrocephalus: 

A.    Skull x-ray: can show 

  Separation of sutures. 
  Features of increased intracranial pressure  

B.    Ultrasound of the brain: 

  can be done through opened anterior fontanelle to see the ventricular system. 

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. 

E.    Lumbar puncture:  

  Can be done in communicating hydrocephalus for both diagnostic and therapeutic 

aims. 

Management of Hydrocephalus: 

A. Medical management of Hydrocephalus: 

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

B. Surgical management: 

1.  Removal of obstructing lesion e.g. removal of tumour will resolve hydrocephalus. 

2.  Bypassing obstruction: either by: 

a.  Endoscopic third ventriculostomy 

b.  External drainage of CSF 

c.  Internal diversion (Shunting) 

Types of Internal Shunts 

  Ventriculo-Peritoneal Shunts. 
  Ventriculo-Atrial Shunts. 
  Ventriculo-Pleural Shunts. 

 
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The complications of shunting 

  Shunt obstruction:  
  Shunt infection. 
  Intracranial haemorrhage either: 

o  Intracerebral haemorrhage,  or 
o  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 

 
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  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: 

A.  Conservative Treatment: 

1.  Weight loss (the patients are usually obese). 
2.  Stopping any medication that may have led to the disease, e.g. oral contraceptives, 

tetracycline. 

3.  Diuretic therapy. 
4.  Acetazolamide (reduces CSF production). 
5.  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: 

1.  Persistent severe papilloedema despite conservative measures 
2.  Failing vision. 
3.  Intractable headaches despite conservative measures. 

The surgical procedures that can be performed are: 

•  Optic nerve sheath decompression 
•  Lumboperitoneal shunt.