What is a craniotomy?

Indications and Procedures

Problems requiring craniotomy include tumors, abscesses, hematomas, and vascular
lesions. The cranium may also be opened to excise an area of cortex or to disrupt various nerves and fiber tracts for the relief of pain, seizures, tremors, or spasms that do not respond to pharmacologic therapy. Skull fractures and other traumatic head wounds may be repaired by opening the cranium. Bony defects, dural tearing, bleeding, and removal of penetrating objects are also treated with this procedure. In case of a neoplasm (tumor), the goal of surgery is to remove the pathology completely while preserving the normal neural and vascular structures.

In craniotomy, the skin is cut to the skull bone. Small bleeding arteries are sealed with electric current, and the skin is pulled back. Three burr holes are drilled into the skull, and a fine-wire Gigli’s saw is used to connect the holes. The skull piece is hinged open, and the dura mater, a tough membrane covering the brain, is dissected away. After the required procedure on the brain is completed, the dura mater is stitched together, the bone flap is replaced and secured with soft wire, and the scalp incision is closed.

An intracranial operation can be considered a planned head injury, and the complications are similar. Postoperatively, the degree of impairment depends on the extent of damage to neural tissue caused both by the neurological disorder and by surgical manipulation. Damage may be transient or permanent.

Uses and Complications

With craniotomy, complications include cerebral edema (swelling), which is a normal reaction to the manipulation and retraction of brain tissue. Periorbital edema and ecchymosis (bleeding under the skin) usually follow frontal and temporal surgery. Focal motor deficits result from cerebral edema and are transitory. Permanent focal motor deficits may occur and are a direct and predictable consequence of the surgical procedure or the result of a complication such as stroke. Hematomas are the most devastating and dreaded complication. The clots may be extradural, intradural, or both and usually are caused by a single bleeding vessel rather than a generalized bleed.

Pain and discomfort are expected following cranial surgery, with headache being most common. Pain control may be accomplished with mild analgesics. Fever may occur following operations in the region of the upper brain stem and hypothalamus, and it requires vigorous treatment. Infection may occur, with the risk being greater following open head trauma and if a cerebrospinal fluid leak is present. Postoperative seizure risk is related to the underlying pathological condition and the degree of damage caused by surgery. Diabetes insipidus and the syndrome of inappropriate antidiuretic hormone (SIADH) secretion are also possible complications of craniotomy. These endocrine disorders may be transient or permanent. If unchecked, either may be life-threatening because of the severity of the fluid and electrolyte imbalance precipitated.

A cerebrospinal fluid leak may occur immediately following surgery but usually appears later in the postoperative course. Fluid seeps from the wound edges. Discharge from the nose (rhinorrhea) or ears (otorrhea) of cerebrospinal fluid is frequent with basal skull fractures, but these conditions may also occur following surgery in the frontal sinus or mastoid cavity. Anosmia
(loss of sense of smell) frequently occurs following head injury or frontal craniotomy. Visual loss may be caused by damage to the optic nerve, resulting in blindness and lack of response to direct light. Hydrocephalus may develop as a result of postoperative adhesions secondary to blood sealing the subarachnoid space. Postoperative meningitis, abscess formation, and osteomyelitis of the bone flap occur as complications of a break in sterility or the introduction of organisms as a result of a contaminated open wound.

Bibliography

Aminoff, Michael J., David A. Greenberg, and Roger P. Simon. Clinical Neurology. 8th ed. New York: McGraw-Hill Medical, 2012.

Bakay, Louis. An Early History of Craniotomy: From Antiquity to the Napoleonic Era. Springfield, Ill.: Charles C Thomas, 1985.

Jasmin, Luc. "Brain Surgery." MedlinePlus, February 9, 2011.

Kellicker, Patricia Griffin. "Craniotomy." Health Library, February 6, 2013.

Rowland, Lewis P., ed. Merritt’s Textbook of Neurology. 12th ed. Philadelphia: Lippincott Williams & Wilkins, 2010.

Samuels, Martin A., ed. Manual of Neurologic Therapeutics. 7th ed. New York: Lippincott Williams & Wilkins, 2004.