Neurology -- Correspondence for Jin et al., 68 (19) 1618-1621

Correspondence published:

Tracheostomy can fatally exacerbate sleep-disordered breathing in multiple system atrophy: Michael H. Silber (22 August 2007)

Tracheostomy can fatally exacerbate sleep-disordered breathing in multiple system atrophy: Takayoshi Shimohata, Tetsutaro Ozawa, Hideaki Nakayama, Masahiko Tomita, and Masatoyo Nishizawa (22 August 2007)

Reply from the authors: Kazutaka Jin, Hiroshi Onodera, Yasuto Itoyama, Sendai, Japan (22 August 2007)

Tracheostomy can fatally exacerbate sleep-disordered breathing in multiple system atrophy 22 August 2007

Michael H. Silber,
Department of Neurology and Sleep Disorders Center, Mayo Clinic College of Medicine
200 First Street SW, Rochester, MN 55905
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Re: Tracheostomy can fatally exacerbate sleep-disordered breathing in multiple system atrophy

msilber{at}mayo.edu Michael H. Silber

I read the article by Jin et al with interest. [1] I am concerned that the title is misleading and not supported by the authors’ data.
The phenomenon of central sleep apnea (CSA) developing after tracheostomy in multiple system atrophy (MSA) has been noted before and is of uncertain prognostic significance. [2,3] Jin et al describe CSA in seven patients following tracheostomy for vocal cord paralysis. In three patients, polysomnography (PSG) was also performed before surgery. However, comparison of the studies showed that obstructive apneas had changed to central apneas in one patient with a lower apnea-hypopnea index while pre-existing central apneas had increased in frequency in the other two.
As pre-tracheostomy PSG was not reported in the other four patients, it is impossible to know whether there was any change in apnea type or severity. The authors do not mention that any of the patients died during the course of the study. Table E-1 on www.neurology.org indicates that the three patients with both pre- and post-tracheostomy studies survived a mean of 11.4 years from disease onset and 5.8 years after tracheostomy (range 4.3-8.0 years). As the mean life expectancy in MSA is 8-10 years from onset [4], there is no evidence that tracheostomy resulted in reduced life expectancy by “fatally” exacerbating sleep disordered breathing.
CSA should be distinguished from central neurogenic hypoventilation in MSA. The latter condition can result in hypercapnic respiratory failure and may be a factor causing death even in patients who have undergone tracheostomy. However, the patients described by Jin et al actually had lower PaCO2 levels than before tracheostomy with no evidence for hypoventilation. The presence of laryngeal stridor is associated with reduced survival in MSA [5] and there are many reports of sudden death occurring within days to weeks of identification of stridor.
While the first line treatment for mild stridor in MSA is probably continuous positive airway pressure (CPAP) therapy, tracheostomy remains the recommended choice for patients with daytime stridor, immobile vocal cords on laryngoscopy or stridor unresponsive to CPAP.
The article by Jin et al may lead neurologists to erroneously believe that tracheostomy is harmful in this population and should be avoided. On the contrary, it can be save lives in selected patients.
References
1. Jin K, Okabe S, Chida K. et al. Tracheostomy can fatally exacerbate sleep-disordered breathing in multiple system atrophy. Neurology 2007;68:1618-1621.
2. Kavey NB, Whyte J, Blitzer A, Gidro-Frank S. Sleep-related laryngeal obstruction presenting as snoring or sleep apnea .Laryngoscope 1989;99:851 -854.
3. Sadaoka T, Kakitsuba N, Fujiwara Y, Kanai R, Takahashi H. Sleep-related breathing disorders in patients with multiple system atrophy and vocal fold palsy. Sleep 1996;19:479-484.
4. Bower JH, Maraganore DM, McDonnell SK, Rocca WA. Incidence of progressive supranuclear palsy and multiple system atrophy in Olmsted County, Minnesota, 1976-1990. Neurology 1997;49:1284-1288.
5. Silber MH, Levine S. Stridor and death in multiple system atrophy. Mov Disord 2000;15:699-704.
Disclosure: The author reports no conflicts of interest

Tracheostomy can fatally exacerbate sleep-disordered breathing in multiple system atrophy 22 August 2007

Takayoshi Shimohata,
Niigata University
Dept of Neurology, Brain Research Inst, Niigata Univ, 1-757 Asahi-machi-dori Niigata, Japan,
Tetsutaro Ozawa, Hideaki Nakayama, Masahiko Tomita, and Masatoyo Nishizawa
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Re: Tracheostomy can fatally exacerbate sleep-disordered breathing in multiple system atrophy

nishi{at}bri.niigata-u.ac.jp Takayoshi Shimohata, et al.

We read with interest the article by Jin et al regarding the effect of tracheostomy on sleep-disordered breathing in patients with multiple system atrophy (MSA). [1] The authors reported that tracheostomy aggravated central sleep apnea (CSA) thereby increasing the risk of nocturnal sudden death. This observation is clinically important because tracheostomy has been considered the optimal treatment for upper airway obstruction in the advanced stage of MSA. [6]
The results of the study should be interpreted with caution because tracheostomy is usually required in the advanced stage of the disease. The authors compared the sleep apnea parameters of tracheostomized and nontracheostomized patients and demonstrated that disease severity was not different between the two groups using the Hoen and Yahr score. However, the Hoen and Yahr score is not the appropriate parameter for estimating the disease severity in MSA and it is preferable to use the Unified Multiple System Atrophy Rating Scale (UMSARS). [7]
The disease duration of tracheostomized patients was twice as long as that of nontracheostomized patients (6.8±1.4 years and 2.9±0.50 years, respectively), although the authors mentioned that there was no significant difference between the two groups.
In addition, Table 1 indicates that most tracheostomized patients had dysphasia that caused the decrease in body mass indexes. This suggests that the tracheostomized patients had a relatively advanced stage of degenerative changes in the central nervous system because the swallowing function has been shown to become gradually disturbed with disease progression. [8] Therefore, it may be premature to conclude that the tracheostomy exacerbates CSA in patients with MSA.
We also recommend measuring intraesophageal pressure during polysomnography to determine a precise frequency of CSA. Further studies should be performed to determine the effect of tracheostomy on sleep-disordered breathing and the risk of nocturnal sudden death in MSA.
References
6. Munschauer FE, Loh L, Bannister R, Newsom-Davis J. Abnormal respiration and sudden death during sleep in multiple system atrophy with autonomic failure. Neurology 1990;40:677-679.
7. Wenning GK, Tison F, Seppi K, et al. Development and validation of the Unified Multiple System Atrophy Rating Scale (UMSARS). Mov Disord 2004;19:1391-1402.
8. Higo R, Nito T, Tayama N. Swallowing function in patients with multiple-system atrophy with a clinical predominance of cerebellar symptoms (MSA-C). Eur Arch Otorhinolaryngol 2005;262:646-50.
Disclosure: The authors report no conflicts of interest.

Reply from the authors 22 August 2007

Kazutaka Jin,
Department of Neurology, Tohoku University Graduate School of Medicine
1-1, Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan,
Hiroshi Onodera, Yasuto Itoyama, Sendai, Japan
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Re: Reply from the authors

jink{at}em.neurol.med.tohoku.ac.jp Kazutaka Jin, et al.

We reported on the risk of sudden death in tracheostomized patients with MSA.[1] We are satisfied that many neurologists were interested in our paper.
An aggravation of central sleep apnea (CSA) is sometimes observed in “healthy” subjects suffering from obstructive sleep apnea(OSA) after CPAP. This phenomenon is thought to be caused by the following factors: the effect of an alteration in the PaCO2 levels on the respiratory center; and a dysfunction in respiratory rhythmogenesis caused by the removal of the airway obstruction. CSAs might be masked by frequent OSAs before tracheostomy and become obvious after tracheostomy.
Although such phenomena are well-known among respiratory physiologists, our short discussion might not have been sufficient to persuade neurologists. We suggest that it would be beneficial for the readers to review other data.[9-11]
As a matter of course, tracheostomized patients showed more advanced stage and longer duration of the disease than non-tracheostomized patients in our study. We have never mentioned that there was no significant difference of the disease duration between the two groups. In our study, the multivariate model of logistic regression analysis revealed that the occurrence of severe sleep-disordered breathing was associated with the status after tracheostomy even after adjustment for disease duration(p<0.05).
Table E-1 indicates that sleep studies after tracheostomy were performed at a mean of 5.8 years(range 4.3-8.0 years) after the disease onset. However, our tracheostomized patients with MSA have never revealed reduced life expectancy as Dr. Silber pointed out. That is because nocturnal SaO2 monitoring had been performed for the patients.
We were astonished to observe such a fragile respiratory system in MSA.[1,12] Thus, nocturnal SaO2 monitoring has been performed for all tracheostomized patients with MSA. None of these ten patients, including three patients under mechanical ventilation, experienced nocturnal sudden death during the observation period [8.7(1.1) years from the onset]. These data suggest that sudden death in MSA patients results from a dysfunction of the respiratory regulation system.
Exacerbations of hypercapnia are usually slowly progressive and could not be the primary cause of sudden death. We previously studied the respiratory regulation system in patients with MSA and observed marked impairments in the ventilatory response to hypoxia, while the chemosensitivity to hypercapnia was normal.[12] Severely impaired chemosensitivity to hypoxia can greatly increase the risk of sudden death under hypoxic episodes. Therefore, hypercapnia would not likely be the cause of sudden death in MSA patients.
We agree that tracheostomy is a suitable choice of treatment for patients with severe stridor or immobile vocal cords. We emphasize that MSA patients still have a risk of sudden death even after tracheostomy, mainly due to a dysfunction of the respiratory regulation system in the brainstem. As Dr. Nishizawa et al. pointed out, measuring intraesophageal pressure during polysomnography is needed to determine a precise frequency of CSA. The disease subtype, staging, and degree of airway obstruction differ among MSA patients.
Future larger scale studies of the respiratory physiologic findings and clinical outcome of MSA are necessary.
References
9. Xie A, Rutherford R, Rankin F, et al. Hypocapnia and increased ventilatory responsiveness in patients with idiopathic central sleep apnea. Am J Respir Crit Care Med. 1995;152:1950-1955.
10. Badr MS, Kawak A. Post-hyperventilation hypopnea in humans during NREM sleep. Respir Physiol. 1996;103:137-145.
11. Xie A, Skatrud JB, Dempsey JA. Effect of hypoxia on the hypopnoeic and apnoeic threshold for CO(2) in sleeping humans. J Physiol. 2001; 535:269-278.
12. Tsuda T, Onodera H, Okabe S, et al. Impaired chemosensitivity to hypoxia is a marker of multiple system atrophy. Ann Neurol 2002; 52: 367-371.
Disclosure: The authors report no conflicts of interest.