About Neurosurgery

Mercy Hospital is a not-for-profit surgical hospital committed to delivering 'exceptional care that makes a difference' to Otago and Southland residents. An independent specialist provides neurosurgical services that are concerned with the diagnosis and treatment of disorders of the nervous structures (such as nerves, the brain, or the spinal cord) that can be relieved or cured by surgical intervention. This surgical service is provided at our facility by the following medical specialist. For further information please seek a referral through your GP or contact your preferred specialist directly.


Mr Ahmad Taha
Mr Ahmad Taha
Consultant photo not available
Prof Giles Critchley

Procedures / Treatments

Cerebral Aneurysm

A cerebral (cranial) aneurysm is a weakened section in the wall of a blood vessel in the brain that bulges or balloons out.
Possible causes of cerebral aneurysm include: a defect in the blood vessels present at birth, brain tumour, head trauma or atherosclerosis (fatty deposits start to block the arteries).
A small aneurysm may produce no symptoms but as it grows it might cause vision problems, facial numbness or seizures.
A ruptured or burst aneurysm can cause bleeding in and around the brain which may affect mental skills and bodily functions and may, in serious cases, lead to brain damage, stroke, coma or death.

Surgical Clipping

This is a treatment that can be used for both unruptured and ruptured aneurysms. The skull is opened surgically (craniotomy) and the aneurysm is isolated from the rest of the blood vessel using a small metal clip that seals off each end of the aneurysm.

Endovascular Clipping

This is a less invasive form of treatment that avoids the need for surgery. A catheter (a small, flexible tube) is inserted into an artery in the groin and gently pushed up to the brain. At the site of the aneurysm, the catheter releases soft wire coils that block the aneurysm from inside the blood vessel. Sometimes a tiny balloon is also released to help hold the coils in place.

Brain Tumours

Brain tumours may be primary (they arise in the brain or nearby tissue) or metastatic (they have originated in another part of the body and travelled to the brain). Primary tumours may either be benign (they do not spread to other tissues) or malignant (they spread).

Surgery may be the only treatment approach for a brain tumour, or it may be used in combination with radiation therapy and/or chemotherapy. Typically, the skull is opened up (craniotomy) giving the surgeon access to the tumour and allowing removal of as much of the tumour as possible without damaging brain tissue.

A stereotactic biopsy is another surgical procedure often performed to aid in tumour diagnosis. A small hole is drilled into the skull and a sample of tissue removed for examination under the microscope.

Radiation therapy used high energy x-rays to kill abnormal cells, while chemotherapy uses chemicals (medicines) to destroy cancer cells.

Spinal Tumours

Tumours may be found within the spinal cord itself, between the spinal cord and its tough outer covering, the dura, or outside the dura. They may be primary (they arise in the in the spine or nearby tissue) or metastatic (they have originated in another part of the body and traveled to the spine, usually via the bloodstream).

Spinal tumours may be treated by any combination of surgery, radiotherapy and chemotherapy. Surgery may be performed to take a small sample of tissue to examine under the microscope (biopsy) or to remove the tumour. Typically, the patient will be lying face downwards and a procedure known as a laminectomy is performed (the bone overlying the spinal cord is removed). This gives the surgeon access to the spinal cord and allows removal of the tumour.

Subdural Haematomas

A subdural haematoma is a collection of blood that forms beneath the outer protective covering of the brain, the dura mater. It is usually caused by tiny blood vessels becoming torn as the result of serious head trauma such as a fall, blow to the head or car accident.

 Symptoms include:

  • Headache
  • Speech problems
  • Vision problems
  • Seizures
  • Confusion
  • Weakness
  • Nausea and vomiting

With an acute haematoma, symptoms appear within 24 hours of the trauma while in the case of subacute or chronic haematomas symptoms take longer to appear.

If a haematoma is left to grow, it puts pressure on the brain which may lead to brain damage and possibly death.

Surgical treatment involves drilling a small hole in the skull, allowing the haematoma to drain and thus relieving the pressure on the brain. In the case of a larger haematoma, a hole may be cut in the skull (craniotomy) allowing the surgeon access to the brain to repair damaged vessels and remove the blood clot.

Herniated Discs

Between the vertebrae in your spine are flat, round discs that act as shock absorbers for the spinal bones. Sometimes some of the gel-like substance in the center of the disc (nucleus) bulges out through the tough outer ring (annulus) and into the spinal canal. This is known as a herniated or ruptured disc and the pressure it puts on the spinal nerves often causes symptoms such as pain, numbness and tingling.
Initial treatment for a herniated disc may involve low level activity, nonsteroidal anti-inflammatory medication and physiotherapy. If these approaches fail to reduce or remove the pain, surgical treatment may be considered.


This surgery is performed to remove part or all of a herniated intervertebral disc.

Open discectomy – involves making an incision (cut) over the vertebra and stripping back the muscles to expose the herniated disc. The entire disc, or parts of it are removed, thus relieving pressure on the spinal nerves.

Microdiscectomy – this is a ‘minimally invasive’ surgical technique, meaning it requires smaller incisions and no muscle stripping is required. Tiny, specialised instruments are used to remove the disc or disc fragments.

Laminectomy or Laminotomy

These procedures involve making an incision down the centre of the back and removing some or all of the bony arch (lamina) of a vertebra.
In a laminectomy, all or most of the lamina is surgically removed while a laminotomy involves partial removal of the lamina.
By making more room in the spinal canal, these procedures reduce pressure on the spinal nerves. They also give the surgeon better access to the disc and other parts of the spine if further procedures e.g. discectomy, spinal fusion, are required.

Spinal Fusion

In this procedure, individual vertebrae are fused together so that no movement can occur between the vertebrae and hence pain is reduced. Spinal fusion may be required for disc herniation in the cervical region of the spine as well as for some cases of vertebral fracture and to prevent pain-inducing movements.


Surgical repair of a bone defect in the skull that’s left behind after a previous operation or injury.

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