Hyperventilation-Induced Tetany: a Case Report and Brief Review of the Literature

Neurological Bulletin

Volume 1 Issue 1 Article 3

2009-10-21

Hyperventilation-Induced Tetany: A Case Report and Brief Review of the Literature

Daniel Schneider University of Massachusetts Medical School

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Repository Citation Schneider D. Hyperventilation-Induced Tetany: A Case Report and Brief Review of the Literature. Neurological Bulletin 2009;1:11-13. https://doi.org/10.7191/neurol_bull.2009.1002. Retrieved from https://escholarship.umassmed.edu/neurol_bull/vol1/iss1/3

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Neurol. Bull. 1: 11-13, 2009 http://escholarship.umassmed.edu/neurol_bull doi:10.7191/neurol_bull.2009.1002

Hyperventilation-Induced Tetany: A Case Report and Brief Review of the Literature

Daniel Schneider

Department of Neurology University of Massachusetts Medical School, Worcester, MA

The consultation for a paroxysmal event is a handed female who reported that she was common diagnostic challenge for neurolo- driving earlier in the day when suddenly she gists. Diagnoses such as seizure and transient experienced paresthesias in her hands and ischemic attack are often in the differential feet. These rapidly spread over her entire and this can have significant implications for body, including her face. About 30 seconds the patient, including limitations on the abil- after the paresthesias began, she found that ity to drive, time lost performing multiple she was unable to move her legs, then arms, tests, and even the prescribing of unneces- and then her entire body. When she began to sary medications. The ability to recognize lose movement of her legs, she turned her car relatively benign syndromes before an exten- into a parking lot and continued at a low sive and unnecessary work-up is begun is speed until she hit a guard rail at the far side therefore imperative in the ideal management of the lot. She denied any loss of conscious- of a patient. ness or confusion after the event. She was told by a bystander that her speech was In this report, I present the case of a healthy “funny,” and she believed he meant it was 22 year old woman who presented to the slurred but was uncertain. She denied incon- Emergency Department (ED) of the Univer- tinence or tongue-biting. She denied anxiety sity of Massachusetts Medical Center follow- or panic prior to episode. She experienced ing a low speed car accident. The preliminary some nausea and vomiting in the AM and differential diagnosis from the ED staff was noted, “I think I was hung over from last seizure vs. conversion disorder, and a neuro- night”. She then elaborated that she drank logical consultation was requested to help about four beers and smoked some marijuana guide the work-up and disposition of the pa- at a concert the night before and explained tient. that this was unusual for her since she rarely drank that much or used marijuana. Case Report There was no significant medical or psychi- The patient was a 22 year old, healthy, right- atric history. Her only medication was a birth

Correspondence to Daniel Schneider: [email protected] Keywords: calcium, Chvostek’s sign, hypocapnia 11 Schneider: Hyperventilation-Induced Tetany

Neurol. Bull. 1: 11-13, 2009 doi:10.7191/neurol_bull.2009.1002 control pill for years. She denied any aller- gies to medications. She currently lived with Hyperventilation can be defined as a state in her mother and was finishing a BA in busi- which breathing in excess of metabolic re- ness management. She had a long-term boy- quirements results in hypocapnia.1 Many friend who was her sole sexual partner. She medical and psychiatric conditions can lead denied any history of abuse or dependence to this condition, and there is a long literature on alcohol or illicit drugs. She did drink alco- examining the body’s response to hypocap- hol on occasion but rarely drank more then 3 nia.1-3 The individual manifestations of hypo- beers and only about once a week on a week- capnia vary widely, but symptoms can in- end. Also she smoked marijuana rarely at clude paresthesias in the face, trunk, and ex- social events. She denied tobacco use or oth- tremitities, fasciculations, and tetany, among er drug use. Her only significant neurological others. family history was ALS in her grandfather. Tetany can be understood as a hyperexcita- Her physical exam was largely unremarka- bility of the axons of peripheral nerves lead- ble. She was afebrile and her vital signs were ing to the generation of repetitive discharg- normal. She was appropriately dressed and es;3 it is physically manifested by spasms of well-groomed. Her neck was supple, her the hands and feet (carpopedal), either bilat- heart and lung exam were normal. She was erally or unilaterally.1,2 The most common alert and oriented with intact cognitive func- cause is decreased calcium ion concentration, tions. Her cranial nerves were unremarkable, but the literature reports numerous cases of strength was full with intact bulk and tone normocalcemic tetany in the context of hy- and no abnormal movements noted, reflexes perventilation. The prevailing notion is that 2+ with downgoing toes, and gait, coordina- this is due to alkalosis causing a change in tion and sensation were also normal. the relative amounts of bound versus free calcium ions in the plasma.3 This interpreta- Metabolic panel, including calcium, phos- tion has been supported by the frequent ob- phorus and magnesium, was normal. Her servation that normocalcemic patients with blood count was normal. A urine HCG was tetany still present with Chvostek’s sign or a negative. An EKG was performed that re- positive Trousseau test, both generally con- vealed sinus tachycardia at 104 bpm. sidered indicative of low calcium. However, this theory has come under fire in recent The most pertinent, and ultimately most re- years, as some have argued that other factors vealing, test was forced hyperventilation. She such as magnesium deficiency,4 hypoglyce- was asked to hyperventilate for three minutes mia,5 or malfunction at the brainstem reticu- and after about one minute she began to ex- lar formation unrelated to ionic imbalance6 perience the same paresthesias she had re- also may be playing a role. ported earlier and shortly thereafter experienced a spastic flexion of both hands and feet Once the diagnosis of hyperventilation and in a pattern characteristic of tetany. She re- tetany is made, the next step is to evaluate ported that all these symptoms exactly repli- the patient for causative factors. Many disor- cated her presenting complaint. On further ders have been implicated in hyperventilation exam, she also had a positive Chvostek’s and hypocapnia, including respiratory diseas- sign on the left. es (including asthma), left ventricular failure, pulmonary emboli, chronic pain, aspirin Discussion overdose, anxiety and panic states, prolonged

12 Schneider: Hyperventilation-Induced Tetany

Neurol. Bull. 1: 11-13, 2009 doi:10.7191/neurol_bull.2009.1002 talking, pyrexia, pregnancy, and the second 3. Macefield G, Burke D. Paraesthesiae and half of the menstrual cycle. 1, 7, 8 Additional- tetany induced by voluntary hyperventila- ly, and of most relevance to my patient, there tion. Increased excitability of human cuta- have been case reports and studies of patients neous and motor axons. Brain 1991;114 presenting with hyperventilation and result- (Pt 1B):527-540. ing tetany in the context of headaches, pre- 4. Fehlinger R, Seidel K. The hyperventila- sumably due to changes in breathing in reac- tion syndrome: a neurosis or a manifesta- tion to the discomfort. 9 tion of magnesium imbalance? Magnesi- um 1985;4:129-136. In my patient, the diagnosis was made when 5. Anantharaman V. Hypoglycaemic tetany-- a trial of hyperventilation reproduced her a case report. Singapore Med J symptoms; the presence of a Chvostek’s sign 1988;29:524-525. while normocalcemic supported this interpre- 6. Kukumberg P. Hyperventilation tetany: tation. In some patients, attacks of hyperven- effect of carbamazepine. J Neurol Neuro- tilation-induced tetany are common surg Psychiatry 1991;54:937. (spasmophilia), and a chronic hyperventila- 7. Gardner WN, Bass C, Moxham J. Recur- tion syndrome can develop. This is frequent- rent hyperventilation tetany due to mild ly associated with anxiety, but an underlying asthma. Respir Med 1992;86:349-351. organic etiology can also be the cause.10 The 8. Moss PD, McEvedy CP. An epidemic of treatment of this syndrome is often directed overbreathing among schoolgirls. Br Med toward identifying and treating the underly- J 1966;2:1295-1300. ing cause, but at least one small study argues 9. Narchi H. A child with headaches and ab- that carbamazapine may be effective.6 normal movements. Eur J Pediatr 2000;159:219-221. In the case of my patient, the diagnosis was 10. Sarma RN, Rao KB. Tetany: An Analysis hyperventilation leading to paresthesias and of Fifty Cases. J Indian Med Assoc normocalcemic tetany. This syndrome was 1963;41:588-598. most likely brought on by the combination of her headache and any lasting metabolic changes brought on by the alcohol the night Disclosure: the authors report no conflicts of interest. before. As this was the only time she had ev- er had these symptoms, she was advised to All content in Neurological Bulletin, unless otherwise noted, is licensed under a Creative Commons avoid drinking to excess and to follow-up Attribution-Noncommercial-Share Alike License with us or her primary care doctor should the http://creativecommons.org/licenses/by-nc-sa/3.0/ symptoms recur. (ISSN 1942-4043)

References

1. O'Sullivan G, Harvey I, Bass C, Sheehy M, Toone B, Turner S. Psychophysiologi- cal investigations of patients with unilat- eral symptoms in the hyperventilation syndrome. Br J Psychiatry 1992;160:664-667. 2. Kukumberg P. Side-specific electromyo- graphic differences in tetany. Lancet 1991;337:1607.