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Tuesday, June 07, 2016

Traumatic brain injury and paroxysmal coughing

Traumatic brain injury and paroxysmal coughing don't add up to a single malady. Or do they?

H ere's an unusual case: Hillary Clinton had a brain injury resulting from a fall after fainting due to dehydration. Shortly thereafter, reports started circulating about her having ‘coughing fits’: episodes of paroxysmal coughing. This seems like a very unusual combination. Are there any conditions that could account for both symptoms?

First I tried running the symptoms through an online symptom checker. Even the computer couldn't make sense of them. One of its top suggestions was ‘rabies.’ Although we should keep an open mind, I think that diagnosis can probably be ruled out.

Some have speculated that the coughing fits result from hypothyroidism, which she is known to suffer from. Symptoms of hypothyroidism, according to Harrison's[1], are tiredness, hair loss, difficulty concentrating, weight gain, constipation, weight gain, hoarse voice, paresthesia, and impaired hearing. Contrary to what people are saying on the Internet, I could not find any mention of chronic cough as a symptom of hypothyroidism in any source or textbook.

There is very little in the literature linking these two syndromes. Coutinho et al. [2] discussed a type of autosomal dominant cerebellar ataxia, which is a genetic disease, in 19 Portuguese families in which attacks of spasmodic coughing preceded ataxia (loss of muscle coordination) for 1 to 3 decades. They conclude that spinocerebellar ataxia type 5 and type 20 are the same, and spasmodic coughing is a reliable marker for the disease.

Another case of chronic cough as a symptom of primary brainstem lesion was found in a 69 year old man whose cough preceded progressive truncal ataxia, incoordination, and nystagmus (involuntary movements of the eye)[3]. This patient had a tumor that was compressing the brainstem, causing cough. Chemotherapy got rid of his lymphoma but the cough persisted.

You might be surprised to know that we still aren't sure about the neurological mechanisms of cough. According to some neurologists, the cough center may be located in the brainstem[4].

But I couldn't find much else besides this smattering of papers, other than an old paper[5] where they claimed that cerebral concussion is a cause of cough syncope, which is fainting during a violent coughing episode due to rapid changes in blood pressure.

Greenfield's Neuropathology says[6] that CAT and MRI imaging have shown that the brain stem is frequently damaged in traumatic brain injury. This is something, they say, that was not recognized before the advent of brain imaging. The brain stem is essential for bodily function: primary brainstem hemorrhages carry a mortality rate of 83%, with almost half the survivors being left in a vegetative state.[7]

Even a mild head injury can produce a tentorial coup injury in some patients, depending on their brain anatomy. If a person falls on the back of the head, causing a midbrain contusion, it can also injure the brain stem. It's reasonable to suppose that this could result in a chronic cough, but I couldn't find any cases of it.

There's not much else in the scientific literature suggesting that coughing can be the result of brain trauma. However, a cough syncope can cause a fall and lead to brain injury. This syndrome occurs mostly in males; in one study 82% were current or ex-smokers.[8]

Many things, ranging from excessive vocalization to cancer, can cause chronic coughing. Reports about Hillary's coughing surfaced on the Internet only after reports of brain injury focused attention on her health. Even if they're not related, one thing doctors would agree on: a chronic cough is not always serious, but it's also nothing to sneeze at.

[1] Harrison's Principles of Internal Medicine, 17th ed., p. 2230.

[2] Arch Neurol. 2006 Apr;63(4):553–5. Cerebellar ataxia with spasmodic cough: a new form of dominant ataxia. Coutinho P, Cruz VT, Tuna A, Silva SE, Guimaraes J.

[3] J Surg Case Rep. 2014 Oct 24;2014(10). Chronic cough as a presenting feature of cerebral lymphoma. Williams SP, Bhutta MF.

[4] Eur Respir J. 1995 Jul;8(7):1193–1202. Neurophysiology of the cough reflex. Widdicombe JG.

[5] Arch Intern Med. 1961 Aug;108:248–252. Cerebral concussion as a cause of cough syncope. Keer A Jr, Eich RH.

[6] Greenfield's Neuropathology, 4th ed., p. 777

[7] Zuccarello M, Fiore DL, Trincia G, et al. Traumatic primary brain stem haemorrhage: a clinical and experimental study. Acta Neurochir (Wien) 1983, 67:103–113.

[8] Int J Addict. 1987 May;22(5):413–9. Smoking and cough syncope: follow-up in 45 cases. Bonekat HW, Miles RM, Staats BA.

Revised jun 07 2016, 6:45 pm; last updated jun 08 2016 6:11 am. Minor edits for clarity sep 07, 2016

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