Most of you reading this series would be wondering why this author is bombarding your gray matter with information about conditions that we may never encounter in practice. A very good example to illustrate the point might be the case of a young boy whose glioma of the pons was first detected only after he developed strabismus. My argument is simple; that the eyes are part of the central nervous system and many issues pertaining to the brain could have an effect on one’s sight. Observing pupil sizes and reactions can reveal vital information on one’s actual state of mind.
Each and every one of us, at some stage, has experienced patients fainting during contact lens fitting and some do so on insertion of eye drops. First aid would suggest getting the patient to put their head down to increase blood flow to the head. We often hear about brain tumours, but never actually get to see brain scans and I am grateful to all my patients featured in this series who have given me the opportunity to enhance the knowledge of optometric colleagues.
Case 1
A type 2 diabetic 56-year-old Asian male patient, back in April 2015, suffered from loss of consciousness, confusion, weakness, dizziness and an acute onset headache following a long haul flight. He was referred to a cardiac unit to check for any heart disease. His cardiac diameter, measurement of the diameters of the cardiac cavities (ventricles and atria) as well as the septal wall thickness, were normal. Coronary artery lumen diameter was also normal with no tortuosity or stenosis which would affect blood flow.
The next test was the brain scan which revealed interesting findings.
An axial CT scan (figure 1) showed in detail a 25mm (2.5 x 2.2cm) high density extra-axial dural mass involving the underlying anterior right frontal lobe abutting the superior sagittal sinus (venous drainage) and falx cerebri medially (the dural fold that separates right and left brain). Adjacent to the lesion, small density vasogenic oedema was seen. The mass had regular edges and there was no secondary mass effect or midline shift.
Figure 1: Extra-axial right parietal lobe meningioma of size 2.5 by 2.2cm close to the sagittal sinus (parasagittal) and falx cerebri (the dural fold that separates the right and left brain) with sharp and regular margins
Scattered paranasal sinus inflammatory changes, moderate muco-membraneous reactive changes involving the maxillary, frontal and sphenoid sinuses, were found along with partial opacification of the ethmoid air cells. Mild deviation of the nasal septum right of midline (figure 2) was also present.
Figure 2: Pan-sinusitis, the purple arrow indicating chronic muco-membrane inflammation. The blue arrow indicates deviation of the nasal septum to the right
A diagnosis was made of a meningioma of the right frontal lobe together with vasogenic oedema. The moderate chronic pan-sinusitis explained the dizziness and caused the deviated septum to the right.
This patient’s experience of weakness, confusion, headaches and loss of consciousness led to a decision to treat the meningioma with targeted cyber knife radiation therapy (figure 3).
Figure 3: A head frame is fitted to the patient’s head and gamma rays produced from decaying cobalt 60 are targeted precisely on the tumour
Three months following his successful radiation therapy the patient suffered a couple of seizures at home. Further examination revealed increased vasogenic oedema in the right frontal lobe adjacent to a previously unchanged meningioma (figure 4).
Figure 4: Increasing vasogenic oedema (red arrows) close to the meningioma (purple arrows) which led to the patient suffering multiple bouts of seizures three months subsequent to successful radiotherapy
The patient was prescribed levetiracetam (brand name Keppra), an anti-epileptic drug, and the steroidal anti-inflammatory dexamethasone (4mg twice a day) to control the swelling. The effect of the steroid was to increase blood sugar levels such that he had to be given insulin instead of his usual metformin. He also found the steroid altered his sleep patterns, so much so that he found it hard to sleep. Ask anyone taking steroids and they complain of mood swings together with increased energy and alertness.
Discussion
Meningioma is an extra-axial tumour, meaning it grows outside the brain, and is derived from the meninges. The meninges protect the brain and spinal cord and lie under the skull. They are comprised of three layers; the outermost layer, the dura mater, a middle pia arachnoid mater layer and the innermost pia mater. Meningiomata (meningiomas) grow from the arachnoid cells that form the middle layer and are firmly attached to the dura mater.
Most meningiomas are benign (non-metastatic) and slow growing such that symptoms appear gradually and vary depending on the location and area of the brain affected. Meningiomas, being extra axial, can be thought of as not being true brain tumours, unlike astrocytoma and other metastatic tumours which are intra-axial. Eighty per cent of extra-axial tumours are either meningiomas or schwannomas ( a malignancy of Schwann cells). Figure 5 illustrates the different types of meningioma. Meningiomas are often named according their location and symptoms.
Figure 5: Types of meningioma; F/PS - falx and parasagittal (venous sinus) meningiomas grow from the dural fold; OLF - olfactory groove meningioma grow along the olfactory nerves; SP – sphenoid meningiomas grow along the sphenoid ridge which lies behind the eye; CLIV and F/M – clivus and foramen magnum are posterior fossa meningiomas that grow along the underside of the brain; CBL – cerebellar meningiomas are meningiomas of the cerebellum; V – intraventricular ventricles grow inside the fluid-filled ventricles deep inside the brain; SPINAL – spinal meningiomas grow in the thoracic spinal region
Meningiomas are the second most common type of brain tumour, accounting for approximately 20% of all primary intra-cranial tumours and 12% of all spinal cord tumours in adults. Less than 10% of meningiomas become malignant. They are rare in children and they typically present between the ages of 30 and 70, with women more than twice as likely to develop them when compared to men. The exact cause of meningiomas is not certain, though patients with the genetic disorder neurofibromatosis type 2 (NF2) are particularly vulnerable. Patients exposed to radiation to the head are also at higher risk of developing meningiomas.
Symptoms with meningiomas develop gradually due to the tumour’s slow growth. For this reason, they are rarely diagnosed before they begin to cause symptoms. The most common symptoms can be remembered by the acronym F.C. BLUWNSHES:
- Fainting (syncope)
- Confusion.
- Blurred Vision
- Weakness in arms and legs.
- Numbness of face, arm and leg.
- Speech problems
- Headaches.
- Seizures.
Vasogenic oedema is an extracellular oedema affecting the white matter and due to leakage of fluid from capillaries. It is frequently seen around both primary and secondary brain tumours and also cerebral abscesses.
Gamma knife or cyber knife surgery is not a type of surgery but a treatment. It requires anything from a single or as many as five sessions, each employing a very high dose of radiation given to a very small and precise area. Meningioma, acoustic neuroma, recurring gliomas and many tumours less than 3cms are amenable to radiation treatment.
An external frame is attached to the head and, with computed topography (CT) scanning to monitor the procedure, the head is imaged and 3-dimensional co-ordinates are produced to identify the tumour’s position in relation to the head frame. The tumour is then targeted at the exact distance by gamma rays produced from the decay of cobalt 60. The high energy radiation (measured in Grays, abbreviated as Gy) causes selective ionisation of the tumour tissue. Ionisation is the production and inactivation of harmful ions and free radicals which are responsible for irreparable damage to DNA, protein and lipid resulting in cell death and disruption of further growth.
Case 2
A 26-year-old law graduate took part in a game of football on a warm July afternoon. He did not remember what happened next, until waking up in hospital two days later with his parents by his bedside. It appeared he had had a fall, hit his head on the concrete floor and lay unconscious before being attended to by his friends. They quickly summoned an ambulance which took him to the local hospital.
Figure 6: The left scan shows a concave right temporal lobe haematoma (3.9mm) and left biconvex temporal lobe epidural haematoma (4mm). The middle scan shows a high density spot indicative of a 3rd ventricle acute bleed, while the final scan on the right shows patency of the cerebral circulation with no signs of aneurysm
His CT scan and angiogram are shown in figure 6. This showed;
- A shallow extra-axial haematoma overlying the right cerebral hemisphere, associated subarachnoid blood and a parenchymal (brain tissue) haematoma within the right temporal lobe (3.9mm in size)
- A shallow extra-axial 4mm haematoma overlying the left temporal lobe
- Acute intraventricular bleeding demonstrated by a tiny focus of high density dots within the third ventricle.
- The ventricles and basal cisterns were patent.
- Circle of Willis and its branches were patent.
- No signs of aneurysm and no obvious source for the bleed could be identified
- Anterior and posterior intra cranial circulation were patent.
- No sign of trauma and no history of epilepsy or headaches in the past.
It was concluded that he may have fainted and a fall on the hard surface caused a cerebral contusion (brain bruising similar to bruises that can appear on the skin). No obvious signs of seizures were discovered and no sign of vessel aneurysm or cerebral circulation disturbance. A decision was made to keep him stable and monitor within the hospital environment.
A further scan two days later revealed;
- A size increase in the left extradural haematoma from 4mm to 10mm (figure 7B).
- The right temporal oedema surrounding haemorrhagic contusions had also increased from 3.9mm to 4.5mm (figure 7A).
- Oedema surrounding the right frontal lobe was clearly seen and there is parenchymal swelling with sulci effacement (loss of definition of sulci due to oedema – figure 7C).
- Degree of mid-line shift to the left improved – currently measuring 1.7mm compared to previously 3.3mm.
Eight weeks later, after regression of the haemorrhages and with physiotherapy, the patient was discharged from hospital. He was, however, still off work some four months after the fall and suffered bouts of emotional disturbance, slight memory loss, difficulties working with computers due to photosensitivity and pattern glare, slight balance issues but, thankfully, no problems with speech or vision.
Figure 7A: Right temporal subdural haemorrhage (yellow arrow) increasing in size from 3.9mm to 4.5mm. 7B: Left temporal epidural haemorrhage increased in size from 4mm to 9.9mm. 7C: Right frontal lobe and parenchymal oedema obscuring the sulci which are much more evident and prominent away from the area outlined in white
His family have been long term patients at our practice and they brought him to us to see if any optical or ophthalmic problem could be causing the photophobia. Routine examination proved unremarkable, with no oculomotor abnormality, no fundus abnormalities, and no visual field defects. The patient was reassured that the photophobia would slowly resolve itself. In practice, we have found that most brain injury patients take up to a year to recover.
Discussion
Brain contusions are caused most often by an impact to the head and normally present as swelling in areas below the site of impact, though sometimes in the area opposite to the site of impact. They cause multiple microhaemorrhages due to damaged blood vessels leaking into brain tissue so causing a form of brain bruising.
The interior of the brain has some sharp ridges, and consequently contusions occur in areas of brain tissue under the frontal and temporal lobe. Contusions typically form in a wedge shape, with the widest part being in the outermost part of the brain. People with contusions often spend time unconscious following the injury. There are five types of haemorrhage;
1 Epidural haemorrhages can be due to middle cerebral artery leakage (in 90% of cases) or due to venous leakage from the dura venous sinus. Blood accumulates between the skull and the dura and forms a bi-convex shape.
2 Subdural haemorrhages form in 15% of all cranial trauma, and are caused by torn cortical bridging veins due to a sudden head movement with the brain lagging behind so causing stress on the veins. It is when blood accumulates in the subdural space found between the dura mater and arachnoid mater. A subdural haemorrhage forms a concave shape as it moves or bows towards the brain.
3 Subarachnoid haemorrhages result from the rupture of an aneurysm and cause the most excruciating headache
4 Intraventricular haemorrhages
5 Intraparenchymal or intracerebral haemorrhage occur deep in the brain tissue.
Trauma to the head, fainting and violent trauma to the head can cause bruising to the brain tissue. Our patient may have suffered from dehydration, as it was a hot July day and he was exercising strenuously, and it is likely that he may have fainted resulting in his head hitting the concrete.
Symptoms of contusions include:
- Confusion
- memory loss
- attention problems
- emotional disturbances
- difficulty with motor co-ordination
- numbness
- loss of ability to understand or express speech.
Important signs include pupil anomalies and it is essential to look at the pupils to see whether they are dilated and whether they are reactive to light.
Case 3
A 60-year-old Asian type 2 diabetic was fasting and, during the day, felt a ringing in the ears and followed a few seconds later by the realisation he had been on the floor. The following day his wife saw him faint in front of her eyes and, on questioning, he claimed he had not realised that he had fainted. A few hours later, he had fainted again and this time hit his head on a table, sustaining a slight bleed on his scalp.
His wife immediately called an ambulance and he was hospitalised for tests. CT scans, heart scans, blood tests all proved negative and he experienced no further fainting episodes after three days in hospital. It was initially thought that his fainting was due to his diabetes or perhaps dehydration. He was discharged only to, once again, suffer a further faint. This prompted more intensive investigation and it was then concluded that he may have suffered a vaso-vagal attack.
Discussion
Vasovagal attack, also called a neuro-cardiogenic syncope leading to a loss of consciousness, is mediated by the vagus, the parasympathetic tenth cranial nerve. Vagal C-type nerve fibres connect the heart with the brain stem. Episodes of vasovagal attacks are typically recurrent and occur in predisposed young adults (aged 10 to 30 years) who have been exposed to specific triggers. These include;
- sight of blood
- sexual arousal
- dehydration
- hunger
- lack of sleep
- trauma to the funny bone
- standing up very quickly
- low blood sugar levels
- recreational drugs such as cocaine, marijuana, opiates and alcohol, all of which may affect blood pressure.
Pressure upon the throat, eyes and sinuses (known as vagal reflex stimulation) can also cause fainting. In optometric practices, patients are known to faint during contact lens fitting and occasionally during tonometry.
In most cases of syncope, the prodromal symptoms before fainting are caused by reduced cerebral perfusion and range from a dimming of vision to a complete loss of vision, dizziness, weakness, fatigue and occasionally ringing in the ears (tinnitus).
Any loss of consciousness is usually brief, and falling down triggers a rush of blood to the head allowing the patient to recover quickly.
The mechanism is stimulation of the nucleus tractus solitaire of the brainstem resulting in simultaneous enhancement of the parasympathetic nervous system (vagal) tone and withdrawal of the sympathetic nervous system tone. Two responses, either individually or combined, are behind the vasovagal response:
1 Cardio inhibitory response – a drop in heart rate leading to a decrease in cardiac output resulting in loss of consciousness. This response primarily results from enhancement of the parasympathetic tone.
2 Vasodepressor response - vasodilation leads to a drop in blood pressure, perhaps to as low as 80/20, without any change in heart rate. This response is thought to be the result of withdrawal of the sympathetic nervous tone.
Brief periods of unconsciousness do no harm but the risk of injury due to falls can present the main danger from vasovagal syncope, evident in our case 2 patient.
In younger patients a neural-mediated mechanism is most common, whilst in elderly patients, cardiovascular causes are more prevalent. Also in the over-65s, the effects of blood pressure and diuretic medication, orthostatic and post-prandial hypotension are common causes of cardiac vasovagal syncope. Low sugar levels (hypoglycaemia) and sometimes diabetes can trigger low blood pressure.
Orthostatic hypotension occurs when something interrupts the body’s natural ability in counteracting a drop in blood pressure. When standing up, blood pools to the legs and blood pressure decreases as there is less blood returning to the heart. Normally, baroreceptor cells near the heart and within neck arteries sense this low blood pressure and send signals to brain centres which stimulate the heart to beat faster and pump more blood along with a narrowing of the arteries so as to increase the blood pressure and stabilise it.
Post-prandial hypotension is an excessive decrease in blood pressure (usually in elderly patients) after standing up 30 to 60 minutes after eating a large carbohydrate-heavy meal. Eating small, low carbohydrate meals may be preventative.
Non-pharmacological treatment is the fundamental first step of all treatment plans and may include;
- Crossing of the legs tightly
- preventing dehydration
- stopping alcohol or drug intake
- adjusting or stopping blood pressure medications
In some patients, medication such as beta blockers and serotonin re-uptake inhibitors are thought to help prevent recurrent syncope. Vasopressors such as midodrine, an alpha agonist vasoconstrictor that affects smooth muscle cells both in the arteries and veins without affecting heart rhythm, may also be effective.
Serotonin re-uptake inhibitors, such as paroxetine, reduce central sympathetic nervous system activity and have been found to be useful in reducing recurrent vasovagal syncope.
Kirit Patel is an optometrist in independent practice in Radlett, Hertfordshire.