Chronic Subdural Hematoma: "Symptoms Are Indefinite, and the Diagnosis Cannot Be Made With Certainty"

THE CASE:A 69-year-old retired accountant presents with a 2-month history of daily headaches. The pain is moderate, constant,global, pressure-like, and occasionally pulsating; it is sometimes exacerbated when the patient lies down. He denies nauseaor vomiting, ocular symptoms, weakness, or sensitivity to light. His wife reports that years ago he experienced throbbingheadaches regularly.

About 3 or 4 months ago, the patient fell and hit his head on the nightstand. He did not lose consciousness and,because he felt well, did not seek medical attention.

He occasionally feels lightheaded and has had difficulty remaining asleep at night. His wife has observed increaseddaytime sleepiness, a major and sudden decline in his short-term memory, and personality changes. She no longer letshim drive because on several occasions he became confused and was unable to make appropriate decisions.

The patient has hypertension and atrial fibrillation and is taking metoprolol, digoxin, and warfarin. He is a nonsmokerand has consumed 3 to 5 alcoholic drinks per week for years. Until recently, he was very active.

This slightly lethargic man offers delayed and sometimes inappropriate responses to questions and has no interest inhis environment. He has short-term memory lapses. Blood pressure is normal; heart rate is regular; no evidence ofcarotid bruits. Cranial nerves are normal and there is no papillary edema. Neck is supple. Deep tendon reflexes andcerebellar examination are normal except for a slightly widened gait. There are no pathologic reflexes.

THE DIALOGUE:Headache specialist: Your patient does not demonstrateany focal or lateralized lesions, but he does show somefeatures of dementia.

In people over 50 who have headache of suddenonset and altered mental status, keep a high index of suspicionfor-and try to rule out-an organic intracerebrallesion, especially in the absence of head trauma. Hypothyroidismcan also explain these symptoms; this disorder isrelatively common in older people and is easy to exclude.

Clinician: I did order a noncontrast brain CT for this patient.It showed a large left-sided, hyperdense lesion thatextended from the frontal to the parietal lobe with bloodin the ventricles. The shape and location-and displacementof the brain parenchyma away from the skull-weretypical of chronic subdural hematoma (CSH). But isheadache a classic symptom of CSH?

Headache specialist: Headache is a manifestation of elevatedintracranial pressure. The incidence varies greatly(from 14% to 80%, depending on which study you look at).Headache is more common in younger patients with CSHand may be accompanied by nausea, vomiting, and neckstiffness. The incidence is lower in older patients; this isbecause the enlarged intracranial space from age-relatedcerebral atrophy allows more room for the hematoma.Headache may also occur later in the process in elderlypatients.

As many as 1 in 3 patients with CSH have symptomsof elevated intracranial pressure, such as papilledemaand pathologic reflexes. Changes in personalityand intellect, altered level of consciousness, confusion,disorientation, and aggressive behavior are also verycommon-and often mistaken for dementia or anotherpsychiatric abnormality. Lateralization of neurologicsigns is more common in older patients.

It is difficult to diagnose CSH based on the clinicalpicture alone. William Osler remarked that "the symptomsare indefinite, and the diagnosis cannot be made with cer-tainty." Cerebrovascular accident is initially suspected inalmost 50% of patients, acute infection in 20%, and worseningdementia in 5%. With a high index of suspicion andbrain CT scanning, however, the diagnosis of CSH can beestablished with certainty.

Clinician: How common is CSH, and what are the predisposingfactors?

Headache specialist: There are 1 or 2 cases per 100,000people each year in the general population. The rate increaseswith age and reaches more than 7 per 100,000 inpeople aged 70 to 79 years. The incidence is much higherin men, possibly because they are more prone to trauma.The Table lists the most common risk factors.

Clinician: How might the pathophysiology of CSH affectimaging results?

Headache specialist: The initial trauma to the bridgingveins results in hemorrhage into the subdural space. Aftera relatively short interval, the hemorrhage becomes organizedand a thin layer of fibrin covers the outer surface.Proliferation of fibroblasts leads, within a few days, to formationof a membrane over the clot. The membrane continuesto thicken, and the hematoma inside this closedspace begins to liquefy.

The growth of the hematoma is a result of osmoticforces and recurrent bleeding from the hematoma capsule.The protein in the encapsulated fluid attracts fluid fromthe adjacent vessels, and the recurrent bleeding furtherenlarges the hematoma. The subdural collection can bewatery, bloody, or filled with fresh blood clots.

In the acute phase, the hematoma looks hyperdenseon a CT scan because of the presence of fresh blood.During the next few weeks-the subacute phase-fibrinolysisproduces resolution. The blood collection appearsisodense, and CT diagnosis can be difficult at this stage.Repeated microhemorrhages lead to a more hyperdenseimage. In patients who have isodense lesions without midlineshift, MRI may be required.

Clinician: Is surgery the only treatment option?

Headache specialist: Surgery is not always indicated. Patientswith small hematomas experience spontaneous absorptionof the hematoma and show improvement with repeatedboluses of mannitol and/or high doses of corticosteroids.The standard operative procedure consists of burhole evacuation with closed external drainage of the subduralspace. Following this procedure, 80% to 90% of patientswith CSH recover their previous functional status.Mortality associated with the procedure is less than 5%. Inup to 25% of patients, the fluid collection may recur and requirefurther drainage.

In general, the outcome depends on the patient's initialcondition. CSH is graded on the Bender scale, whichgroups patients according to symptoms as follows:

• Grade 1: mildly symptomatic (headache, confusion,seizure).
• Grade 2: drowsy with variable neurologic deficit.
• Grade 3: stuporous.
• Grade 4: comatose, without motor response to pain, butwith decorticate or decerebrate posturing.

Half of patients have grade 1 CSH. A good outcomeis seen in 75% to 90% of patients in this group, althoughmild disability may persist in 15%. Advanced age and preexistingcerebral infection are associated with poor brainreexpansion. Dementia and other neuropsychiatric abnormalitiesseen in many patients with CSH resolve withsurgery.

Clinician: What are some of the complications of surgery?

Headache specialist: The most common is a re-accumulationof the hematoma. Some residual fluid, detected inas many as 80% of patients, remains clinically silent and isinsignificant. Symptomatic recurrence has been notedwithin 4 weeks in 8% to 37% of patients. Seizures may developin about 11%. Prophylactic anticonvulsant therapy isrecommended for up to 6 months.

References:

FOR MORE INFORMATION:

• Adhiyaman V, Asghar M, Ganeshram KN, Bhowmick BK. Chronic subduralhematoma in the elderly. Postgrad Med J. 2002;78:71-75.
• Chen JC, Levy ML. Causes, epidemiology, and risk factors of chronic subduralhematoma. Neurosurg Clin N Am. 2000;11:399-406.
• Mori K, Maeda M. Surgical treatment of chronic subdural hematoma in 500consecutive cases: clinical characteristics, surgical outcome, complications, andrecurrence rate. Neurol Med Chir (Tokyo). 2001;41:371-381.
• van Havenbergh T, van Calenbergh F, Goffin J, Plets C. Outcome of chronicsubdural hematoma: analysis of prognostic factors. Br J Neurosurg. 1996;10:35-39.