Intracranial elderly

Figure 3.4 Graph showing mean values for cardiac index (Cl) and heart rate (HR) in young (n=20) and elderly (n=20) patients during induction of anaesthesia with isoflurane (1 MAC) in 100% oxygen. Data from McKinney MS, Fee JPH, Clarke F J. British Journal of Anaesthesia 1993 71 696-701.) anaesthesia. Marked cerebral vasodilation occurs with an increase in intracranial pressure. This can be mitigated by hyperventilation even in the presence of a space-occupying lesion.

Cerebral blood flow depends on cerebral perfusion pressure and cerebrovascular resistance. The perfusion pressure is the difference between systemic arterial pressure at the base of the brain when in the recumbent position and the venous pressure at exit from the subarachnoid space, the latter being approximated by the intracranial pressure. Cerebral perfusion pressure divided by cerebral blood flow gives the cerebrovascular resistance. In normal humans, cerebral blood flow remains almost constant when the mean systemic blood pressure is between approximately 50 and 170mmHg, which, under normal circumstances when the intracranial venous pressure is negligible, is the same as the cerebral perfusion pressure. This homeostatic mechanism to maintain a constant cerebral blood flow in the face of changes in cerebral perfusion pressure is known as autoregulation (Reed and Devous 1985 Powers 1993). Autoregulation is less effective in the elderly, and so postural hypotension is more likely to be symptomatic (Wollner et al. 1979 Parry et al. 2006). 

Gradual onset of stroke over hours or days, rather than seconds or minutes, is unusual and is much more likely to occur in ischemic than in hemorrhagic stroke. If the onset is gradual, and not Ukely to be caused by low flow or migraine (Ch. 8), then a structural intracranial lesion must be excluded. In younger patients, multiple sclerosis should also be considered. However, focal neurological deficits that develop over hours, or up to two days, in elderly patients are still most likely to have a vascular cause since vascular disease is so common in older patients. 

Partial or generalized epileptic seizures occur for the first time in about 2% of those with acute strokes at around the time of onset, rising to approximately 10% at five years, more with large cortical infarcts or intracranial hemorrhage (Ch. 9) (Ferro and Pinto 2004). Seizures are more common with large strokes, especially if hemorrhagic, and with cortical as opposed to lacunar strokes. Cerebrovascular disease is the most common cause of epilepsy in the elderly, and late-onset epilepsy is a predictor of subsequent stroke (Cleary et al. 2004). Seizures may cause neurological deterioration or be mistaken for recurrent stroke. Intractable recurrent seizures are distinctly unusual. 

Brass LM, Lichtman JH, Wang Y, Gurwitz JH, Radford MJ, Krumholz HM. Intracranial hemorrhage associated with thrombolytic therapy for elderly patients with acute myocardial infarction results from the Cooperative Cardiovascular Project. Stroke 2000 31 1802-1811. 

Inagawa T, Hada H, Katoh Y (1992) Unruptured intracranial aneurysms in elderly patients. Surg Neurol 38 364-370 Inci S, Erbengi A, Ozgen T (1998) Aneurysms of the distal anterior cerebral artery report of 14 cases and a review of the literature. Surg Neurol 50 130-139 discussion 139-140... 

Absolute history of previous severe allergic reaction to hydrocodone or acetaminophen. Relative head injury, increased intracranial pressure, elderly patient, severe liver or renal impairment, acute abdominal conditions, hypothyroidism, Addison s disease, prostatic hypertrophy, urethral stricture, history of drug abuse, and patients with respiratory depression [8]. 

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