CHAPTER 4 – DIAGNOSIS AND DIFFERENTIAL DIAGNOSIS
Diagnosis is not difficult if one is aware of the syndrome. It must be made on positive grounds with a clear knowledge of the pathogenesis. If a good history is taken the vast majority of cases give a story of periodic attacks of both peripheral and central nervous system disturbances. Such a story, in the absence of any signs of organic nervous disease, suggests the hyperventilation syndrome. If, in addition, there is respiratory distress unrelated to exertion, the diagnosis is certain. If a case presents with central symptoms alone, or with some other effect or overbreathing, such as tachycardia, the diagnosis may become more difficult. If careful attention is paid to all symptoms, however, and not only to the one which has made the deepest impression on the patient, it is usually possible to elicit the characteristic story of respiratory difficulty associated with paresthesia and giddiness. It must be remembered that patients seldom mention any respiratory difficulty because they are not aware of its relevance. In these cases leading questions are probably justified and the report of relatives may prove helpful.
Finally, a hyperventilation test will clinch the diagnosis. The patient is instructed to overbreathe for several minutes at the rate of 30 or 40 breaths per minute. In this series, most patients reproduced, in 1 to 3 minutes, the symptoms of which they had complained. Some took as long as 8 to 10 minutes. It is important to see that they are really overbreathing and to remember that the upright position is the best one for eliciting cerebral symptoms and the recumbent position the best for eliciting peripheral symptoms. The object of the test is to reproduce the patient’s symptoms so that the similarity between the symptoms and those produced by overbreathing is recognized. The time taken to develop the syndrome is not very important, except very broadly, because the depth and rate of breathing vary from patient to patient. A metronome is of help in regulating the rate. Patients also vary from time to time in their susceptibility to the test depending on their emotional state, blood sugar level, etc.
The following are some of the vague or erroneous diagnoses with which these patients presented themselves:
- Neurosis or “Functional disease”
Fifteen patients were thus diagnosed. In other words, their illness was recognized as being of emotional origin, but no further classification was attempted. There can be no real understanding by the doctor or the patient of an illness vaguely labeled “neurosis“. If the patient is getting symptoms as real as paresthesia or tetanic spasm his physiology is disturbed. Hyperventilation is one of the mechanisms by which this disordered physical state is brought about.
Three cases were thought to be epileptic. The diagnosis was made on a story of a sudden loss of consciousness. A careful history showed, however, that all these cases had premonitory signs of respiratory distress. If an attack is witnessed by a doctor the differentiation from an epileptic seizure is easy. In the tetanic “fit” the striking thing is the increased rate and depth of breathing. A general stiffening of the body occurs – opisthotonus is marked – but no motor jerking. Occasionally the posture or the hands is unmistakably tetanic. Consciousness is seldom completely lost though the patient may not respond to pin-prick for a few seconds. Tongue biting and incontinence seldom occur. Cyanosis is relatively uncommon though it may occur if overbreathing is followed by a long period of apnea. Many people imagine that grand mal seizures are readily precipitated by overbreathing. Most authorities say it is very uncommon to induce a grand mal seizure in this way though petit mal attacks are readily so induced. Gibbs, Lennox, and Gibbs (1940) claim that patients with petit mal have a low CO2 level in the blood and so are unusually susceptible to any loss of it through overbreathing.
Three patients were thought to be suffering from hypoglycemic attacks. There are several points of similarity: the periodic nature of the attacks, the excessive sweating, and confusion. However, respiration remains unaffected in hypoglycemia until the patient is deeply comatose and many transient attacks of hypoglycemia are uncommon without some obvious organic disease becoming manifest. One diabetic who was hypoglycemic through insulin overdosage was referred to as a case of the hyperventilation syndrome.
The diagnosis of thyrotoxicosis is always difficult and the physical similarity between an anxious and a thyrotoxic patient is well known. Here again, the respiratory difficulty and the reproduction of symptoms and signs by a hyperventilation test are valuable. Two cases in this series were thought to be thyrotoxic.
- Peripheral vascular disease
Many doctors who are aware of the hyperventilation syndrome do not realize that one of its manifestations is a striking peripheral vasoconstriction which, because of its periodic nature, may be confused with Raynaud’s disease. The relationship to cold is absent, however, and the other manifestations of the hyperventilation syndrome should help to differentiate the two conditions.
One case was admitted to an infectious diseases hospital with this diagnosis because of residual muscle tenderness and a feeling of “lameness” in the legs after a night of overbreathing.
- Organic cardiac disease
Almost half the patients in this series thought they had heart disease. In some cases, this belief had received support from their doctors. The error on the part of the doctor was usually made because of a lack of careful history taking, a fear of missing something organic, and ignorance of the ECG changes that occur with overbreathing. It is a serious error in an already anxious patient. Two patients had spent 6 weeks in bed – diagnosed as cases of coronary thrombosis. Both these patients described a very severe substernal pain and belching with the attack. They had probably been swallowing air and had developed an associated cardiospasm.
- Da Costa’s syndrome
Attempts to explain the symptoms of this syndrome by hyperventilation have been made for a long time White and Hahn (1929) found that 80 of 100 patients with this syndrome had sighing dyspnoea, whereas only 76 of 400 normal controls showed sighing dyspnoea. They concluded that hyperventilation probably accounted for many of the symptoms of Da Costa’s syndrome.
Wood (1941) also investigated the problem and concluded that hyperventilation was unimportant in this syndrome. He thought, however, that the left mammary pain common in Da Costa’s syndrome might be caused by a habit of breathing intercostally with neglect of the diaphragm and resultant diaphragmatic spasm. There may be an overlap here with the hyperventilation syndrome as left mammary pain is not uncommon.
In 1938 Soley and Shock investigated seven patients in detail and concluded that “the respiratory alkalosis resulting from hyperventilation produces the symptoms of effort syndrome.”
In 1945 Friedman said, “although hyperventilation may occasionally be found in patients with neurocirculatory asthenia, it is not an initial aetiological factor of any real importance in the production of the symptoms from which they suffer“.
Although there may be some overlap between these two conditions the dyspnoea in De Costa’s is characteristically related to exertion, and neurogenic dysfunction which is so striking in the hyperventilation syndrome is absent.
Tetanic spasm is not a common feature of the hyperventilation syndrome. It occurred in six patients in this series and two of these patients were alkalotic through vomiting before they hyperventilated. Confusion with other varieties of tetany is unlikely. If difficulty does arise the normal serum calcium level will rule out hypocalcemia and the history will rule out alkalosis from ingestion of alkali or from excessive vomiting.
This condition has in common with the hyperventilation syndrome periodic attacks of paraesthesia in the fingers with no signs of organic nervous disease. Its symptoms, however, are related to posture, not to breathing, and are more often nocturnal. The patient with acroparesthesia often complains of a “bloated” feeling or actual swelling of the fingers. Only on hyperventilation patient (outside this series) complained of swelling of the hand during an attack.
CHAPTER 5 – TREATMENT
- Much of the treatment is built around the hyperventilation test already described, which is not only diagnostic but for the following reasons, of immense therapeutic importance:
(a) The majority of patients think that their symptoms are due to some serious organic disease. The reproduction of these symptoms by overbreathing does more than any words can do to assure them that either no serious organic disease is present, or, if such disease is present, it is not the cause of the symptoms and should be dealt with as a separate problem. A not uncommon example of the co-existence of the syndrome with organic disease is the patient who has had a cardiac infarction and has become anxious about his heart. The anxiety results in hyperventilation which causes distressing symptoms. The patient automatically assumes that these symptoms indicate that his heart condition is worse.
(b) During the test the patient is shown how much more difficult it is to hyperventilate through the nose and the value of nasal breathing in preventing hyperventilation is emphasized. Air swallowing is impossible with nasal breathing.
(c) Some observers, impressed by the predominantly intercostal character of these patients’ breathing, stress the importance of teaching them to breathe abdominally.
(d) A demonstration of the relief gained from symptoms by breath-holding or by re-breathing into a paper bag or hat etc., is an essential part of the test. Breath-holding is ideal because it not only relieves the symptoms which result from loss of CO2 but also relieves symptoms such as peripheral vasoconstriction, tachycardia, etc., which result from the mechanical act of overbreathing. Many patients, however, find it impossible to hold their breath because the sensation of “not getting enough air into the chest” is so overpowering. If they re-breathe into a bag or hat the relief of the alkalotic symptoms usually eventually stops the hyperventilation
- Medication is usually not necessary apart from sedation in anxious patients. For this purpose phenobarbitone, ½ – 1 grain three times a day, and sodium amytal 1 – 3 grains at night is useful.
- Calcium is of doubtful value. Many patients have been given calcium gluconate intravenously by their doctors during attacks or hyperventilation tetany and said that it relieved their symptoms. It is possible that the mere fact of calling in a doctor was so reassuring that they stopped overbreathing. It is not justifiable to keep a patient on regular calcium or vitamin D medication. O’Donovan’s claim that such therapy abolishes hypersensitivity to the effects of overbreathing is an isolated report and the therapy is not without danger.
- Kerr, Oliebe, Soley, and Shock (1939) found ammonium chloride of value in “acidifying” their patients so that it became more difficult for them to become alkalotic if they did overbreathe.
- The emotional stress which has caused the hyperventilation usually needs to be treated. The association between breathing disorder and stress is explained to the patient and he is given the opportunity to discuss his emotional problems. Occasionally this happens quite spontaneously immediately after a hyperventilation test because of loss of cortical inhibition.
No attempt was made to do any extensive psychoanalysis on the patients in this series. Patients appeared to adjust themselves well if given an early opportunity to discuss their problems.
Psychotherapy is not always necessary. Some patients, once shown the technique for breaking the vicious circle of symptoms from which they are suffering, appear able to make a good general adjustment on their own.
- The technique of progressive relaxation was taught to all patients who were very tense.