Case history

A 75 year old man presented with a four week history of an acute confusional state, marked weight loss, and deteriorating mobility. After admission he suffered a grand mal seizure. He was known to have longstanding essential hypertension controlled with atenolol and chlorthalidone. He had smoked 15 cigarettes a day for almost 40 years. He had previously worked as an electrician and had occasionally been in contact with asbestos sheets.

On examination he was drowsy with a Glasgow coma scale of 8/15, haemodynamically stable with a blood pressure of 108/60 mm Hg, and a heart rate of 76 beats/min with an irregular rhythm. He was apyrexial and there were no obvious signs of sepsis. Chest examination revealed tracheal deviation to the left, decreased left sided chest expansion, normal breath sounds and no additional sounds. Neurological examination revealed left sided signs with decrease in power of 4/5, normal reflexes, and up going plantar.

Investigations on admission

Haemoglobin 14.0 (normal range 11.0-16.5) g/l, white cell count 9.79 (4-11) * 10⁹/l, platelets 418 (140-400) * 10⁹/l, erythrocyte sedimentation rate 60 (0-10) mm in first hour, albumin 24 (35-50) g/l, phosphate 1.09 (0.75-1.40) g/l, corrected calcium 2.38 (2.22-2.56) g/l, alkaline phosphatase 110 (30-120) g/l, sodium 132 (135-145) g/l, potassium 3.4 (3.7-5.0) g/l, urea 8.2 (3.5-8.0) g/l, creatinine 136 (50-105) g/l, glucose 22.3 g/l, haemoglobin A_1c 9.7% (3.6%-6.8%), C reactive protein 59 (<10).

Liver and thyroid function test results were normal. On 4 litres of oxygen, arterial blood gases were pH 7.365 (7.35-7.45), Po₂ 23.15 (>10.6) kPa, Pco₂ -7.16 (4.7-6.0) kPa, and bicarbonate 30 (24-30) mmol/l.

Questions

1. What are the possible causes of this patient's acute confusional state?
2. Describe the chest x ray and computed tomography head findings
3. What is the diagnosis?
4. What is the likely explanation for the electrolytes and bicarbonate?
5. What is the calculated serum osmolality?

Answers:

(1) (a) Cerebrovascular accident

(b) Intracranial haemorrhage

(c) Hyperglycaemia

(d) Sepsis elevated white cell count in absence of clinical signs

(e) Malignancy

(f) Hypercapnia

(g) Space occupying lesion

(h) Depression

(i) Constipation

(j) Temporal lobe epilepsy

(k) Rapid dementia process

(2) The chest x ray film shows loss of the aortic arch and right heart border, loss of cardiac silhouette sign, and an elevated left hemidiaphragm. There is complete left upper lobe and lingular collapse and hyperinflated right lung.

The computed tomographic scan of the head shows multiple metastatic deposits in the right frontal lobe and right side of the brain stem extending to the right thalamus. There is surrounding oedema and mass effect. The lateral ventricles are distorted and displaced medially.

(3) Bronchogenic carcinoma with cerebral metastasis.

(4) Hypokalemic alkalosis and hyponatraemia could be explained on the basis of secretion of ectopic adrenocorticotrophic hormone and antidiuretic hormone, respectively.

(5) Calculated serum osmolality using the formula [2(Na+K)+urea+glucose] is 301.3 (normal range 275-305) mmol/kg.

Non-metastatic effects

• Hypertrophic pulmonary osteoarthropathy
• Thrombophlebitis migrans
• Non-bacterial thrombotic endocarditis
• Anaemia, pruritus, herpes zoster
• Acanthosis nigricans and Erythema gyratum repens
• Gynaecomastia
• Endocrine--Syndrome of inappropriate secretion of antidiuretic hormone secretion, ectopic adrenocorticotrophic hormone, and parathormone
• Neuropathy--Peripheral neuropathy, encephalopathy, cerebellar degeneration
• Proximal myopathy, polymyositis, and dermatomyositis
• * Eaton-Lambert syndrome--reversed myasthenia

Discussion

The overwhelming majority of older adults are active, independent, and mentally intact. Physiological changes that occur with ageing and the comorbidity of multiple illnesses lead to atypical presentation of diseases in elderly people. Serious illness can be present despite non-specific symptoms and findings. The non-specific presentation of disease includes confusion, falls, immobility, incontinence--each of which may be the result of specific, often remediable, and commonly multiple disease processes. These factors make the history and physical examination especially challenging in older adults. Elderly people have been found to have more undiagnosed disease, greater morbidity and mortality, and longer recovery times than other groups.¹

Small cell bronchogenic carcinoma comprises 20% of cases of lung cancer, and 50% metastasise to the brain. The average time interval between the diagnosis of a primary lung tumour and metastasis to the brain is four months. Sixty per cent of patients with brain metastases have subacute symptoms. Headache, seizures, and cognitive dysfunction are the most common presenting symptoms, and 33% have motor dysfunction on direct questioning. New onset of seizures in a patient older than 35 years is highly suggestive of primary or metastatic disease.²

Medical management of metastatic diseases has focused mainly on the treatment of headache, cerebral oedema, and seizures.³ Cerebral oedema of metastatic disease is mainly vasogenic, which results in secondary insult to the surrounding healthy brain, which may result in worsening of cognitive function with or without motor and sensory deficits. Severely compromised cerebral perfusion results in cerebral infarction. Dexamethasone is the treatment of choice for cerebral oedema. Thirty to forty per cent of patients with metastatic brain tumours have seizures. Half of patients who experience seizures have seizure as their presenting symptom. Status epilepticus occurs infrequently but carries a high mortality (6-35%).

Radiotherapy provides significant palliation in all forms of bronchogenic carcinoma. Small cell bronchogenic carcinoma is highly susceptible to radiation and the median survival is 3-6 months depending on number of lesions, their radiosensitivity, and the status of systemic disease. Prevention and risk avoidance, particularly smoking cessation, are the best means for reducing morbidity of bronchogenic carcinoma.