ON ExAMINATION.-she was a friendly, happy, and attractive child of normal development and nutrition. She was mentally retarded, but less so than one would expect as a result of her confined existence. The head circumference was 24% in. ; but, apart from enlargement of the head, hydrocephalus appeared to cause no symptom, nor was there any evidence of brain-stem compression. The upper limbs were normal. Over the upper part of the sacrum was a tough, thick-walled sac, which measured 26 in. in diameter. There were bed-sores 2 in. in diameter over the ischial tuberosities. Structures supplied by sacral nerves showed almost complete paralysis ; but the thigh muscles were strong, and easily able to support the body-weight. There was a little fixed flexion of hips and knees. It was thought that she could be made to walk, and that orthopaedic treatment would be well worth while if the hydrocephalus could be arrested. There was no indication to interfere with the sac in the sacral region. OPERATION (Dec. I, 1945).-Operation was performed under local anaesthetic, without using a telescope. In the days following operation, changes in cerebrospinal fluid pressure, although less marked than in Case I, were clearly reflected in the size and tension of the sacral sac, which became smaller, softer, and more wrinkled. Changes in size were recorded by taking plaster casts of the sac. During the month since operation her vocabulary and general knowledge have increased enormously; and she has learned to walk with the aid of a walking frame.
SUMlMARY
I.A simple and apparently safe method of performing third ventriculostomy (floor of the ventricle) by means of a hollow needle introduced from above by way of the lateral ventricle, foramen of Monro, and third ventricle is described.
2.It is hoped that the method will be of use to surgeons who, in the past, have hesitated to use more formidable procedures.3. I n the past, third ventriculostomy has been reserved for cases of non-communicating hydrocephalus.4. The division of hydrocephalus into communicating and non-communicating types is an arbitrary one, and has been over-emphasized. Two cases are reported to show that there are also types of communicating hydrocephalus which respond to third ventriculostomy.5. Cauterization of the choroid plexus seems to be wrong in principle. Also floating debris after operation must sometimes aggravate the hydrocephalus.6. Suggestions are made for the prevention and treatment of the type of hydrocephalus associated with lumbar meningomyelocele.