A subarachnoid haemorrhage (SAH) occurs when there is spontaneous bleeding into the subarachnoid space and is often a catastrophic event. The incidence of SAH is 9 cases per 100,000 people per year, and it typically affects individuals between the ages of 35 and 65.

The majority of SAH cases (80%) are caused by the rupture of berry (saccular) aneurysms, while 15% are caused by arteriovenous malformations (AVM). In less than 5% of cases, no specific cause can be found. Berry aneurysms are associated with polycystic kidneys, Ehlers-Danlos Syndrome, and coarctation of the aorta.

There are several risk factors for SAH, including smoking, hypertension, bleeding disorders, alcohol misuse, mycotic aneurysm, and a family history of the condition.

Patients with SAH typically experience a sudden and severe occipital headache, often described as the worst headache of my life. This may be accompanied by vomiting, collapse, seizures, and coma. Clinical signs of SAH include neck stiffness, a positive Kernig’s sign, and focal neurological abnormalities. Fundoscopy may reveal subhyaloid retinal haemorrhages in approximately 25% of patients.

Re-bleeding occurs in 30-40% of patients who survive the initial episode, with the highest risk occurring between 7 and 14 days after the initial event.

Untreated SAH has a mortality rate of nearly 50% within the first eight weeks following presentation. Prolonged coma is associated with a 100% mortality rate.

The first-line investigation for SAH is a CT head scan, which can detect over 95% of cases if performed within the first 24 hours. The sensitivity of the CT scan increases to nearly 100% if performed within 6 hours of symptom onset. If the CT scan is negative and there are no contraindications, a lumbar puncture (LP) should be performed at least 12 hours after the onset of headache to diagnose SAH. Approximately 3% of patients with a negative CT scan will be confirmed to have had an SAH following an LP.

The normal intracranial pressure (ICP) for an adult lying down is typically between 5 and 15 mmHg.

Further Reading:

Intracranial pressure (ICP) refers to the pressure within the craniospinal compartment, which includes neural tissue, blood, and cerebrospinal fluid (CSF). Normal ICP for a supine adult is 5-15 mmHg. The body maintains ICP within a narrow range through shifts in CSF production and absorption. If ICP rises, it can lead to decreased cerebral perfusion pressure, resulting in cerebral hypoperfusion, ischemia, and potentially brain herniation.

The cranium, which houses the brain, is a closed rigid box in adults and cannot expand. It is made up of 8 bones and contains three main components: brain tissue, cerebral blood, and CSF. Brain tissue accounts for about 80% of the intracranial volume, while CSF and blood each account for about 10%. The Monro-Kellie doctrine states that the sum of intracranial volumes is constant, so an increase in one component must be offset by a decrease in the others.

There are various causes of raised ICP, including hematomas, neoplasms, brain abscesses, edema, CSF circulation disorders, venous sinus obstruction, and accelerated hypertension. Symptoms of raised ICP include headache, vomiting, pupillary changes, reduced cognition and consciousness, neurological signs, abnormal fundoscopy, cranial nerve palsy, hemiparesis, bradycardia, high blood pressure, irregular breathing, focal neurological deficits, seizures, stupor, coma, and death.

Measuring ICP typically requires invasive procedures, such as inserting a sensor through the skull. Management of raised ICP involves a multi-faceted approach, including antipyretics to maintain normothermia, seizure control, positioning the patient with a 30º head up tilt, maintaining normal blood pressure, providing analgesia, using drugs to lower ICP (such as mannitol or saline), and inducing hypocapnoeic vasoconstriction through hyperventilation. If these measures are ineffective, second-line therapies like barbiturate coma, optimised hyperventilation, controlled hypothermia, or decompressive craniectomy may be considered.

Haloperidol should not be used in patients with Parkinson’s, Lewy body dementia, or prolonged QT syndrome. It is the first choice for controlling aggressive behavior in most patients with delirium, but lorazepam is preferred for patients with Parkinson’s, Lewy body dementia, prolonged QT syndrome, extrapyramidal side effects, or delirium due to alcohol withdrawal. Haloperidol can reduce the effectiveness of levodopa in Parkinson’s disease by blocking dopamine receptors in the corpus striatum, which can lead to worsened motor function, psychosis, or a combination of both.

Further Reading:

Delirium is an acute syndrome that causes disturbances in consciousness, attention, cognition, and perception. It is also known as an acute confusional state. The DSM-IV criteria for diagnosing delirium include recent onset of fluctuating awareness, impairment of memory and attention, and disorganized thinking. Delirium typically develops over hours to days and may be accompanied by behavioral changes, personality changes, and psychotic features. It often occurs in individuals with predisposing factors, such as advanced age or multiple comorbidities, when exposed to new precipitating factors, such as medications or infection. Symptoms of delirium fluctuate throughout the day, with lucid intervals occurring during the day and worse disturbances at night. Falling and loss of appetite are often warning signs of delirium.

Delirium can be classified into three subtypes based on the person’s symptoms. Hyperactive delirium is characterized by inappropriate behavior, hallucinations, and agitation. Restlessness and wandering are common in this subtype. Hypoactive delirium is characterized by lethargy, reduced concentration, and appetite. The person may appear quiet or withdrawn. Mixed delirium presents with signs and symptoms of both hyperactive and hypoactive subtypes.

The exact pathophysiology of delirium is not fully understood, but it is believed to involve multiple mechanisms, including cholinergic deficiency, dopaminergic excess, and inflammation. The cause of delirium is usually multifactorial, with predisposing factors and precipitating factors playing a role. Predisposing factors include older age, cognitive impairment, frailty, significant injuries, and iatrogenic events. Precipitating factors include infection, metabolic or electrolyte disturbances, cardiovascular disorders, respiratory disorders, neurological disorders, endocrine disorders, urological disorders, gastrointestinal disorders, severe uncontrolled pain, alcohol intoxication or withdrawal, medication use, and psychosocial factors.

Delirium is highly prevalent in hospital settings, affecting up to 50% of inpatients aged over 65 and occurring in 30% of people aged over 65 presenting to the emergency department. Complications of delirium include increased risk of death, high in-hospital mortality rates, higher mortality rates following hospital discharge, increased length of stay in hospital, nosocomial infections, increased risk of admission to long-term care or re-admission to hospital, increased incidence of dementia, increased risk of falls and associated injuries and pressure sores.

This patient has developed Wernicke’s encephalopathy, a condition that is associated with alcohol abuse and other causes of thiamine deficiency. It is important to note that the infusion of glucose-containing intravenous fluids without thiamine in a patient with chronic thiamine deficiency can trigger Wernicke’s encephalopathy. In this particular case, it seems that this is what has occurred.

Wernicke’s encephalopathy is typically characterized by a triad of symptoms, which include acute confusion, ophthalmoplegia, and ataxia. Additionally, other possible features of this condition may include papilloedema, hearing loss, apathy, dysphagia, memory impairment, and hypothermia. It is also common for peripheral neuropathy, primarily affecting the legs, to occur in the majority of cases.

This condition is characterized by the presence of acute capillary haemorrhages, astrocytosis, and neuronal death in the upper brainstem and diencephalon. These abnormalities can be visualized through MRI scanning, although CT scanning is not very useful for diagnosis.

If left untreated, most patients with Wernicke’s encephalopathy will go on to develop a Korsakoff psychosis. This condition is characterized by retrograde amnesia, an inability to form new memories, disordered time perception, and confabulation.

Patients who are suspected to have Wernicke’s encephalopathy should be promptly treated with parenteral thiamine (such as Pabrinex) for a minimum of 5 days. Following the parenteral therapy, oral thiamine should be administered.

Occlusion of the branches of the basilar artery that supply the midbrain leads to the development of Weber’s syndrome. This condition is characterized by contralateral hemiplegia, which affects the limbs, face, and tongue due to damage to the descending motor tracts within the crus cerebri. Additionally, there are ipsilateral deficits in eye motor activity caused by damage to cranial nerve III.

Wernicke’s encephalopathy is a condition that is commonly associated with alcohol abuse and other causes of thiamine deficiency. It is characterized by a classic triad of symptoms, including acute confusion, ophthalmoplegia (paralysis or weakness of the eye muscles), and ataxia (loss of coordination). Additional possible features of this condition may include papilloedema (swelling of the optic disc), hearing loss, apathy, dysphagia (difficulty swallowing), memory impairment, and hypothermia. The majority of cases also experience peripheral neuropathy, which typically affects the legs.

The condition is marked by acute capillary haemorrhages, astrocytosis (increase in the number of astrocytes, a type of brain cell), and neuronal death in the upper brainstem and diencephalon. These abnormalities can be visualized using MRI scanning, while CT scanning is not very useful for diagnosis.

If left untreated, most patients with Wernicke’s encephalopathy will go on to develop a Korsakoff psychosis. This condition is characterized by retrograde amnesia (loss of memory for events that occurred before the onset of amnesia), an inability to form new memories, disordered time perception, and confabulation (fabrication of false memories).

When Wernicke’s encephalopathy is suspected, it is crucial to administer parenteral thiamine (such as Pabrinex) for at least 5 days. Following the parenteral therapy, oral thiamine should be continued.

Subfalcine herniation occurs when a mass in one side of the brain causes the cingulate gyrus to be pushed under the falx cerebri. This condition often leads to specific neurological symptoms. These symptoms include a motor deficit in the lower limb on the opposite side of the body, bladder incontinence, motor and sensory deficits on the same side of the body as the herniation, and difficulty with speech (dysarthria).

Further Reading:

Intracranial pressure (ICP) refers to the pressure within the craniospinal compartment, which includes neural tissue, blood, and cerebrospinal fluid (CSF). Normal ICP for a supine adult is 5-15 mmHg. The body maintains ICP within a narrow range through shifts in CSF production and absorption. If ICP rises, it can lead to decreased cerebral perfusion pressure, resulting in cerebral hypoperfusion, ischemia, and potentially brain herniation.

The cranium, which houses the brain, is a closed rigid box in adults and cannot expand. It is made up of 8 bones and contains three main components: brain tissue, cerebral blood, and CSF. Brain tissue accounts for about 80% of the intracranial volume, while CSF and blood each account for about 10%. The Monro-Kellie doctrine states that the sum of intracranial volumes is constant, so an increase in one component must be offset by a decrease in the others.

There are various causes of raised ICP, including hematomas, neoplasms, brain abscesses, edema, CSF circulation disorders, venous sinus obstruction, and accelerated hypertension. Symptoms of raised ICP include headache, vomiting, pupillary changes, reduced cognition and consciousness, neurological signs, abnormal fundoscopy, cranial nerve palsy, hemiparesis, bradycardia, high blood pressure, irregular breathing, focal neurological deficits, seizures, stupor, coma, and death.

Measuring ICP typically requires invasive procedures, such as inserting a sensor through the skull. Management of raised ICP involves a multi-faceted approach, including antipyretics to maintain normothermia, seizure control, positioning the patient with a 30º head up tilt, maintaining normal blood pressure, providing analgesia, using drugs to lower ICP (such as mannitol or saline), and inducing hypocapnoeic vasoconstriction through hyperventilation. If these measures are ineffective, second-line therapies like barbiturate coma, optimised hyperventilation, controlled hypothermia, or decompressive craniectomy may be considered.

The median nerve originates from the lateral and medial cords of the brachial plexus and receives contributions from the ventral roots of C5-C7 (lateral cord) and C8 and T1 (medial cord). It serves both motor and sensory functions.

In terms of motor function, the median nerve innervates the flexor muscles in the anterior compartment of the forearm, excluding the flexor carpi ulnaris and a portion of the flexor digitorum profundus, which are instead innervated by the ulnar nerve. Additionally, it innervates the thenar muscles and the lateral two lumbricals.

Regarding sensory function, the median nerve gives rise to the palmar cutaneous branch, which provides innervation to the lateral part of the palm. It also gives rise to the digital cutaneous branch, which innervates the lateral three and a half fingers on the palmar surface of the hand.

Within the forearm, the median nerve branches into two major branches. The first is the anterior interosseous nerve (AIN), which supplies the flexor pollicis longus, pronator quadratus, and the lateral half of the flexor digitorum profundus. The second is the palmar cutaneous branch, which provides sensory innervation to the skin of the radial palm.

Differentiating between damage to the median nerve at the elbow and wrist can be done by considering these two branches. Injury at the elbow affects these branches, while injury at the wrist spares them. It is important to note that the palmar cutaneous branch travels superficially to the flexor retinaculum and therefore remains functional in carpal tunnel syndrome. However, it can be damaged by laceration at the wrist.

A comparison of median nerve lesions at the wrist and elbow is presented below:

Median nerve at elbow:
– Motor loss: Weak wrist flexion and abduction, loss of thumb abduction and opposition, loss of flexion of index and middle fingers
– Sensory loss: Lateral 3 and ½ fingers and nail beds, lateral side of palm
– Hand deformity: Ulnar deviation of wrist, thenar wasting, papal benediction on flexing fingers

Median nerve at wrist:
– Motor loss: Loss of thumb abduction and opposition, wrist and finger flexion intact (due to intact AIN)
– Sensory loss: Lateral 3 and ½ fingers and nail beds, lateral side of palm (but can be preserved depending upon palmar cutaneous branch)
– Hand deformity: Thenar wasting, no ulnar deviation of wrist or papal benediction (due to intact AIN)

Wernicke’s encephalopathy is a condition that is commonly associated with alcohol abuse and other causes of thiamine deficiency. It is characterized by a triad of symptoms, including acute confusion, ophthalmoplegia (paralysis or weakness of the eye muscles), and ataxia (loss of coordination). Additional features may include papilloedema (swelling of the optic disc), hearing loss, apathy, dysphagia (difficulty swallowing), memory impairment, and hypothermia. Most cases also involve peripheral neuropathy, which typically affects the legs.

The condition is caused by capillary hemorrhages, astrocytosis (abnormal increase in astrocytes, a type of brain cell), and neuronal death in the upper brainstem and diencephalon. These changes can be visualized using MRI scanning, although CT scanning is not very useful for diagnosis.

If left untreated, most patients with Wernicke’s encephalopathy will develop Korsakoff psychosis. This condition is characterized by retrograde amnesia (loss of memory for events that occurred before the onset of amnesia), an inability to form new memories, disordered time perception, and confabulation (fabrication of false memories).

Patients suspected of having Wernicke’s encephalopathy should receive parenteral thiamine (such as Pabrinex) for at least 5 days. Oral thiamine should be administered after the parenteral therapy.

It is important to note that in patients with chronic thiamine deficiency, the infusion of glucose-containing intravenous fluids without thiamine can trigger the development of Wernicke’s encephalopathy.

The NICE recommendations for managing patients with suspected TIA are as follows:

– Offer aspirin (300 mg daily) to individuals who have experienced a suspected TIA, unless there are contraindications. This treatment should be started immediately.
– Immediately refer individuals who have had a suspected TIA for specialist assessment and investigation. They should be seen within 24 hours of the onset of symptoms.
– Avoid using scoring systems, such as ABCD2, to assess the risk of subsequent stroke or determine the urgency of referral for individuals with suspected or confirmed TIA.
– Provide secondary prevention measures, in addition to aspirin, as soon as possible after confirming the diagnosis of TIA.

The NICE recommendations for imaging in individuals with suspected TIA or acute non-disabling stroke are as follows:

– Do not offer CT brain scanning to individuals with suspected TIA, unless there is clinical suspicion of an alternative diagnosis that CT could detect.
– After a specialist assessment in the TIA clinic, consider performing an MRI (including diffusion-weighted and blood-sensitive sequences) to determine the area of ischemia, detect hemorrhage, or identify alternative pathologies. If an MRI is conducted, it should be done on the same day as the assessment.
– Carotid imaging is necessary for all individuals with TIA who, after specialist assessment, are considered candidates for carotid endarterectomy. This imaging should be done urgently.

For more information, refer to the NICE guidelines on stroke and transient ischaemic attack in individuals over 16 years old: diagnosis and initial management.