Cardiac arrhythmias associated with spinal cord injury

Abstract

Context/Objectives

To review the current literature to reveal the incidence of cardiac arrhythmias and its relation to spinal cord injury (SCI).

Methods

Data source: MEDLINE database, 304 hits, and 32 articles were found to be relevant. The relevant articles all met the inclusion criteria: (1) contained original data (2) on cardiac arrhythmias (3) in humans with (4) traumatic SCI.

Results

In the acute phase of SCI (1–14 days after injury) more cranial as well as more severe injuries seemed to increase the incidence of bradycardia. Articles not covering the first 14 days after injury, thus describing the chronic phase of SCI, showed that individuals with SCI did not have a higher incidence of cardiac arrhythmias compared with able-bodied controls. Furthermore, their heart rate did not differ significantly. Penile vibro-stimulation was the procedure investigated most likely to cause bradycardia, which in turn was associated with episodes of autonomic dysreflexia. The incidence of bradycardia was found to be 17–77% for individuals with cervical SCI. For individuals with thoracolumbar SCI, the incidence was 0–13%.

Conclusion

Bradycardia was commonly seen in the acute stage after SCI as well as during procedures such as penile vibro-stimulation and tracheal suction. These episodes of bradycardia were seen more often in individuals with cervical injuries. Longitudinal studies with continuous electrocardiogram recordings are needed to uncover the true relation between cardiac arrhythmias and SCI.

Introduction

If uncontrolled by the autonomic nervous system, the human heart beats at a rate of approximately 100 beats per minute (bpm),¹ which is the spontaneous rate produced by the pacemaker cells in the sinoatrial node situated in the wall of the right atrium. During rest the normal heart rate (HR) is considerably lower reflecting the inhibiting action of the parasympathetic tone.² The parasympathetic fibers, controlling the heart, exit the central nervous system at brain stem level, i.e. the vagal nerve (cranial nerve X). In contrast, the sympathetic control of the heart originates from the upper thoracic spinal cord segments (Th1–Th5). A trauma to the cervical region of the spinal cord will therefore typically only influence the spinal sympathetic neurons involved in heart regulation. It is known that sympathetic and parasympathetic innervations typically function in opposition to each other. Parasympathetic action depresses the HR, while activation of sympathetic nervous system results in increase in HR and stroke volume to increase the cardiac output when needed.

Unopposed parasympathetic control is believed to cause episodes of marked bradycardia and asystolia. Injuries that damage the spinal sympathetic pathways that control the heart and maintain the vascular tone below the level of spinal cord injury (SCI) are more likely to result in neurogenic shock and of developing HR abnormalities that could contribute to early mortality following SCI.³ It is therefore important to be aware of this additional cardiovascular challenge when investigating cardiac arrhythmias after SCI.

The ultimate goal is to be able to identify patients in need of aggressive pharmacological therapy and temporary or permanent cardiac pacemaker soon after injury. These therapies, in combination with vascular support, could potentially avoid life-threatening neurogenic shock in the acute phase of SCI.

The incidence of cardiac arrhythmias among individuals with SCI remains unclear, especially in the group of individuals with thoracic injuries. If clinicians could stratify patients by high and low risk for cardiac arrhythmias and death after SCI, lives could perhaps be saved. The aim is therefore to review the incidence of cardiac arrhythmias among individuals with traumatic SCI reported in the literature, including the possible effect of the level and the severity of the spinal cord lesion.

Method

In January and June 2011 and in August 2012, MEDLINE searches were carried out using the search terms (arrhythmias, cardiac OR electrocardiography) AND (paraplegia OR spinal cord injury OR tetraplegia OR quadriplegia).

After filtering out all non-English articles, this rendered 304 hits.

Inclusion criteria required that the articles (1) contained original data, (2) on cardiac arrhythmias, (3) in humans, with (4) traumatic SCI.

Arrhythmias were defined according to The Minnesota Code Classification System⁴. If the author's definition of bradycardia differed from the ‘below 50 bpm’ standard stated by The Minnesota Code Classification System, then the authors’ definition was reported with the result of the study. Therefore, the definitions of bradycardia presented in Tables 1–3 are not always the same, occasionally making direct comparison impossible. Among the 304 articles were 19 reviews and 24 animal studies. After considering the titles of the 261 remaining articles, 175 were excluded because they were not found to be relevant. The articles were excluded if the title indicated that the studied illness was anything else than SCI or if the objective was to study the effect of a medication. Articles that tested the efficiency of surgery or surgical implants were likewise excluded. If there was any doubt to the relevance of the article, the abstract was read.

Table 1.

Reported arrhythmias within the first 14 days after SCI, i.e. acute category

First author and year	Population characteristics	Results according to neurological level or severity of SCI, numbers (%)	Bradycardia defined as heart rate less than
Franga (2006)7	30 Patients with cervical SCI		60 bpm
	30 Cervical	5 (17) Bradycardia
Garner (1985)8	10 Patients, 10 able-bodied controls		60 bpm
	2 C5	1 (50) Bradycardia, 1 (50) JPB
	4 C6	2 (50) Bradycardia (one patient with nodal rhythm, tachycardia, and atrial fibrillation)
	2 C7	2 (100) Bradycardia
	2 C8	1 (50) Bradycardia
	10 Controls	*
Guly (2007)11	301 Patients with cervical SCI		60 bpm
	301 Cervical	75 (25) Bradycardia
Lehmann (1987)9	71 Patients		60 bpm
	31 Frankel A + B cervical	31 (100) Bradycardia, 6 (19) supraventricular tachycardia, 2 (6) ventricular tachycardia, 5 (16) cardiac arrest
	17 Frankel C + D cervical	6 (35) Bradycardia
	23 Frankel A − E Thoracolumbar	3 (13) Bradycardia
Moerman (2011)10	106 Patients with cervical SCI		60 bpm
	106 Cervical	15 (14) Bradycardia
Piepmeier (1985)12	45 Patients with cervical SCI		50 bpm
	31 Frankel A + B	25 (81) Bradycardia, 6 (19) supraventricular tachycardia, 2 (6) ventricular tachycardia
	14 Frankel C + D	4 (29) Bradycardia 1 (7), supraventricular tachycardia
Winslow (1986)13	374 Patients		50 bpm
	83 Complete cervical injury	22 (26) Bradycardia
	153 In-complete cervical injury	*
	98 Thoracic	0 (0) Bradycardia
	40 Lumbar	0 (0) Bradycardia

JPB, junctional premature beat.

*Incidence of arrhythmias not reported for this group.

Table 2.

Reported arrhythmias after the first 14 days after SCI, i.e. chronic category

First author and year	Population characteristics	Results according to neurological level and severity of SCI, numbers (%)	Bradycardia defined as heart rate less than
Claydon (2006)15	27 patients		60 bpm
	19 AIS A	5 (26) Bradycardia (one patient had tachycardia and VPB)
	7 AIS B	1 (14) Bradycardia
	1 AIS C	0 (0) Bradycardia
	19 Cervical	5 (26) Bradycardia
	8 Thoracic	1 (13) Bradycardia (one patient had tachycardia and VPB)
Claydon (2006)16	13 male patients		60 bpm
	8 AIS A	3 (38) Bradycardia (one patient also had VPB and APB)
	3 AIS B	3 (100) Bradycardia,
	2 AIS C	1 (50) Bradycardia
	8 Cervical	4 (50) Bradycardia
	5 Thoracic	3 (60) Bradycardia (one patient also had VPB and APB)
Blocker (1983)14	98 Patients	Not indicated who had the cardiac arrhythmias. 2 (2% of 98) VPB	**
	41 Cervical,
	44 Thoracic
	4 Lumbar
	9*
Kessler (1986)17	14 patients, 7 controls	No arrhythmias found	**
	7 Cervical
	7 Thoracic
	7 Controls
Leaf (1993)18	47 patients		**
	25 Cervical	4 (16) VPB
	17 Thoracic
	5 Lumbar	1 (20) VPB
Prakash (2002)19	654 Patients and 26734 controls		**
	394 Th5 and above	7 (2) Atrial fibrillation, 7 (2) VPB
	260 Th6 and below	2 (1) Atrial fibrillation, 5 (2) VPB
	26734 Able-bodied controls	727 (3) Atrial fibrillation, 1170 (4) VPB

AIS, American Spinal Injury Association Impairment Scale; JPB, junctional premature beat; VPB, ventricular premature beats; APB, atrial premature beat.

*Patients not found in other groups.

**Bradycardia not used or not systematically reported in these studies.

Table 3.

Arrhythmias in individuals with spinal cord injury exposed to specific provocations

First author and year	Population characteristics	New arrhythmias during/after exposure, numbers (%)	Provocation	Bradycardia defined as heart rate less than
Claydon (2006)16	27 patients	No clinically significant changes compared with the resting electrocardiographic activity?	Arm cycling exercise	60 bpm
	19 AIS A
	7 AIS B
	1 AIS C
	19 Cervical
	8 Thoracic
Claydon (2006)15	13 male patients		Penile vibro-stimulation	60 bpm
	8 AIS A	5 (63) Bradycardia, 3 (38) VPB, 3 (38) APB
	3 AIS C	3 (67) VPB 2 (67) APB
	2 AIS C	1 (50) Bradycardia
	8 Cervical	4 (50) Bradycardia, 4 (50) APB, 1 (13) VPB
	5 Thoracic	2 (40) Bradycardia, 1 (20) VPB
Dollfus (1965)20	7 patients	No arrhythmias found	Tracheal suction	***
	6 Cervical
	1 Thoracic
Garner (1985)8	10 patients cervical, 10 able-bodied controls	No new arrhythmias reported	Facial water immersion	***
	2 C5
	4 C6
	2 C7
	2 C8
	10 Controls
Guttmann (1963)21	17 patients	No arrhythmias reported	Tilting	***
	7 Cervical
	10 Thoracic
Hopman (1992)22	11 patients, 11 controls	No arrhythmias reported	Arm exercise	***
	11 Thoracic
	5 Knee and foot injured
	6 Able-bodied
West (2012)23	7 participants cervical		Wheelchair exercise	***
	6 AIS A	6 Tachycardia (100)
	1 AIS B	1 Tachycardia (100)
Yoo (2001)24	54 patients, 20 controls		Laryngoscopy	60 bpm
	22 Cervical	1 (5) Bradycardia, 1 (5) tachycardia, 1 (5) dysrhythmias
	8 Thoracic T1–T4	2 (25) Bradycardia, 6 (75)* tachycardia, 2 (25) dysrhythmias
	24 Thoracic below T5	0 (0) Bradycardia, 8 (33)* tachycardia, 4 (17) dysrhythmias
	20 Controls	0 (0) Bradycardia, 3 (15) tachycardia, 2 (10) dysrhythmias
Yoo (2003)25	160 patients, 25 controls		Tracheal intubation	60 bpm
	26 Cervical <4 weeks	12 (46)* Bradycardia, 0 (0) tachycardia, 1 (4) dysrhythmias
	27 Cervical >4 weeks	2 (7) Bradycardia, 2 (7) tachycardia, 2 (7) dysrhythmias
	24 Below T5 <4 weeks	1 (4) Bradycardia, 6 (25) tachycardia, 4 (17) dysrhythmias
	29 Below T5 >4 weeks	3 (10) Bradycardia, 14 (48)* tachycardia, 4 (14) dysrhythmias
	25 Controls	2 (8) Bradycardia, 3 (12) tachycardia, 2 (8) dysrhythmias
Yoo (2010)26	214 Patients, 20 able-bodied controls		Tracheal intubation	60 bpm
	27 Cervical <4 weeks	9 (33)* Bradycardia, 0 (0) tachycardia, 2 (7) dysrhythmias
	23 Below T5 <4 weeks	2 (9)** Bradycardia, 3 (13) tachycardia, 3 (13)** dysrhythmias
	14 Cervical 4 weeks–1 year	1 (7) Bradycardia, 2 (14) tachycardia, 1 (7) dysrhythmias
	21 Below T5 4 weeks–1 year	1 (5) Bradycardia, 7 (33)* tachycardia, 1 (5) dysrhythmias
	9 Cervical 1–5 years	2 (22) Bradycardia, 2 (22) tachycardia, 0 (0) dysrhythmias
	22 Below T5 1–5 years	2 (9) Bradycardia, 11 (50)* tachycardia, 1 (5) dysrhythmias
	10 Cervical 5–10 years	1 (10) Bradycardia, 0 (0) tachycardia, 1 (10) dysrhythmias
	30 Below T5 5–10 years	4 (13) Bradycardia, 11 (37)* tachycardia, 2 (7) dysrhythmias
	10 Cervical 10–20 years	1 (10) Bradycardia, 0 (0) tachycardia, 2 (20) dysrhythmias
	29 Below T5 10–20 years	4 (14) Bradycardia, 8 (28) tachycardia, 3 (7) dysrhythmias
	1 Cervical >20 years	0 (0) Bradycardia, 0 (0) tachycardia, 0 (0) dysrhythmias
	18 Below T5 >20 years	2 (9) Bradycardia, 3 (13) tachycardia, 3 (13) dysrhythmias
	20 Controls	2 (11) Bradycardia, 1 (6) tachycardia, 3 (10) dysrhythmias

AIS, American Spinal Injury Association Impairment Scale; JPB, junctional premature beat; VPB, ventricular premature beats; APB, atrial premature beat; dysrhythmia, ventricular or supraventricular premature beat or any sustained rhythm other than sinus.

*P<0.05 vs. control group.

**P<0.05 vs. cervical group.

***Definition of bradycardia used, not stated in the article.

The abstracts of the remaining 86 articles were read, and 40 additional articles were excluded because the content was not relevant for the review.

The 46 remaining articles were all read in extenso and 24 of these were found to meet the inclusion criteria of this review. The reference lists of the original articles, as well as the reviews were hand searched for possible relevant articles, but no additional references were found this way. Finally, we made several MEDLINE searches which in different constellations combined the search terms: spinal cord injury with pace maker, arrhythmias, tachycardia, bradycardia, heart block, atrial flutter, and autonomic dysreflexia. This search resulted in the inclusion of eight more articles referred to as ‘free-search’ in the flow diagram (Fig. 1).

Figure 1.

Flow diagram showing the process towards the final inclusion of articles for the review. Free search refers to a series of searches combining different relevant search terms in the MEDLINE database. (+1) The acute category (Table 1) contains one article also present in the specific exposure category. (+2) The chronic category (Table 2) contains two articles also present in the specific exposure category.

The original articles were divided into three categories:

• Studies that covered the time 1–14 days after the SCI were placed in the acute category.

• Articles with results that did not cover the first 2 weeks after SCI were placed in the chronic category.

• Articles describing arrhythmia occurring in direct relation to, for example, tracheal suctioning, exercise, or penile vibro-stimulation were placed in the specific exposure category.

• Data from articles in the specific exposure category often covered resting arrhythmias before the exposure. Those data also appear in the chronic category.

The results were presented according to the level or severity of neurological injury, or both. The level of neurological injury was referred to as cervical if it included the neck region, as thoracic if the chest region was involved and as lumbo-sacral if the lowest part of the spinal cord was injured. To present the severity of injury, the American Spinal Injury Association (ASIA) Impairment Scale (AIS)⁵ or the Frankel Grade⁶ are reported in accordance with the scale used.

Results

Acute

All articles in the acute category (Table 1) found bradycardia in patients with acute cervical SCI.^7–13 Lehmann et al.⁹ also found a trend related to the Frankel grade, i.e. individuals with more severe cervical injuries (Frankel A–B) had a higher incidence of bradycardia than those with less severe cervical injuries (Frankel C–D). Piepmeier et al.¹² found a similar trend. Winslow et al.¹³ reported 22 cases of bradycardia in a population of 374 patients with SCI. For all of the results mentioned above the bradycardia was self-limiting within 3–5 weeks and peaked at day 4–6 after injury (Fig. 2).

Figure 2.

Incidence of bradycardia within the first 14 days after spinal cord injury.

Supraventricular tachycardia was found in 19% of patients with severe cervical SCI with Frankel grade A and B.^9,12 This was only reported in individuals with cervical injuries. Ventricular tachycardia, nodal rhythm, junctional premature beats, atrial fibrillation, and cardiac arrest were also seen in small numbers of patients with acute cervical SCI (Table 1). For studies defining bradycardia as HR less than 60 bpm, the incidence was 14–77% for individuals with cervical SCI. The same incidence was 26–64% for studies using HR less than 50 bpm as definition of bradycardia (see Table 1). The incidence of other arrhythmias was 18–27% and 0% for individuals with cervical and thoracolumbar SCI, respectively.

Chronic

In the chronic category (Table 2) the results were less uniform.^14–19 The two articles by Claydon et al.^15,16 were the only examples in the chronic category that reported data on bradycardia. The study samples were small, but they found that 26–50% of the individuals with cervical and 13–60% of the individuals with thoracic SCI presented with bradycardia. All studies, that used bradycardia as variable, defined this as HR less than 60 bpm. Likewise ventricular premature beats (VPB) were frequent, although Prakash et al.¹⁹ reported that VPB was not more common among individuals with SCI than in able-bodied controls. Prakash et al.¹⁹ used computerized analysis to identify electrocardiogram (ECG) abnormalities in 654 patients with chronic SCI, and compared the result with those of 26 734 able-bodied controls. They reported that individuals with chronic SCI had no greater risk of having atrial fibrillation than the able-bodied controls. The level of neurological injury had no effect on atrial fibrillation or VPB in their study. The SCI group and the able-bodied controls did not differ significantly in mean HR.¹⁹ Leaf et al.¹⁸ made follow-ups on 47 patients with cervical, thoracic, and lumbar SCI during a 2-year period without finding any ‘clinical significant’ arrhythmias.

Specific exposure

In the specific exposure category (Table 3) the authors studied the response in HR to various stimuli including effects of exercise, penile vibro-stimulation, tracheal suction and intubation, facial water-immersion, and tilting in individuals with SCI.^{8,15,16,20–26} Claydon et al.¹⁵ reported that 6 of 13 male participants with cervical SCI developed new bradycardia when undergoing penile vibro-stimulation for sperm retrieval. Furthermore, some of these participants had episodes of atrial premature beats and VPB during or after the procedure. The severity or level of neurological injury had no influence on the results of this study.

Yoo et al.²⁶ divided their 214 participants in to groups categorized by level and time after injury (Table 3). They reported that individuals, with acute SCI <4 weeks, developed bradycardia more often than able-bodied controls, when being intubated before surgery. The participants with acute cervical injury developed bradycardia more often than the participants with acute injury below Th5. The participants with injuries older than 4 weeks did not develop bradycardia more often than the able-bodied controls, but individuals with chronic and low injuries had higher incidences of tachycardia after intubation.

Case reports

Bradycardia was the most commonly reported arrhythmia in the case reports, but tachycardia, atrial, and ventricle fibrillation were also reported.^27–38 The majority of cases of arrhythmia were reported during episodes of autonomic dysreflexia among individuals with cervical SCI. The patients were between 16 and 60 years of age and all were male. Bradycardia was often seen and Welply et al.³⁸ even reported two cases of cardiac arrest during tracheal suction. But spontaneous events of bradycardia were also reported. All except one³⁰ described that the participants had permanent or temporary pacemaker insertion.

Discussion

This review provides further evidence that bradycardia is a common problem among individuals with acute SCI. However, not much can be concluded about the relationship between other cardiac arrhythmias and SCI. Some studies, in the acute category, reported supraventricular tachycardia, ventricular tachycardia, and even cardiac arrest in patients with cervical injuries. None of the arrhythmias mentioned above were found in patients with thoracic injuries or in any control group. This could be a coincidence but it could also be a sign of the autonomic instability that is often seen after SCI to the cervical region¹² or by episodes of autonomic dysreflexia. The severity of injury seems to influence the risk of bradycardia, for persons with cervical injuries in the acute stage.^9,12,39 This could likewise be explained by the autonomic imbalance of the heart rate control after SCI.⁹ After high-level SCI the spinal sympathetic pathways involved in maintaining HR are disrupted, leaving the heart with unopposed parasympathetic vagal tone⁴⁰. This imbalance creates vulnerability to exogenous stimuli such as tracheal suction,²⁶ but also to spontaneous episodes of bradycardia.⁹ The incidence of bradycardia peaked at days 4–6 ^8,9,12 (Fig. 2) and were self limiting within 2–6 weeks after injury.^9,13 The largest study published to date showed that individuals with chronic SCI were not at greater risk of having cardiac arrhythmia nor did they have a lower resting HR than persons with intact CNS.¹⁹ In this study the level and severity of SCI had no influence on the prevalence of arrhythmias in the chronic stage.¹⁹

It has been documented previously that a patient with SCI and no history of heart disease experienced atrial fibrillation after sperm retrieval by penile vibro-stimulation.³⁴ Claydon et al.¹⁵ documented this procedure to be the most arrhythmogenic studied in this review, inducing bradycardia in 63% and VPB in 38% of the individuals with complete SCI (AIS A) (Table 3). The majority of individuals (10 out of the 13 participants) showed marked increase in mean arterial blood pressure, indicating that ejaculation induced autonomic dysreflexia (systolic blood pressure increase by >20 mmHg). Many of the men were unaware of these changes. For safety reasons, Claydon et al.¹⁵ therefore suggest that individuals with SCI should be appropriately monitored during penile vibro-stimulation for sperm retrieval.

A pacemaker implantation was required in up to 17% (2–17%) of all patients with cervical injuries.^7,41,42 This large variation could result from small study samples or perhaps different clinical adherence in pacemaker implantation guidelines. Patients who received a pacemaker were characterized by a high level of injury; all but one had a neurological lesion above C5.^7,41,42 Most bradyarrhythmias occurred during tracheal suction, events of hypoxia or when being turned in bed but spontaneous events of bradycardia were also recorded.⁷ Four out of the 10 cases described in three studies died before discharge from the hospital.^7,41,42 Individuals with SCI have increased mortality due to cardiovascular causes in the chronic stage.⁴³ Some of these events could be the result of cardiac arrhythmias induced by autonomic dysreflexia.

Limitations

The incidence of bradycardia reported in the reviewed studies ranged between 14–77% and 26–64% depending on the definition of bradycardia used, i.e. HR <50 bpm or HR <60 bpm, respectively. The lack of a clearer difference in this respect is somewhat unexpected but visualizes the challenge of comparing data across small and heterogeneous studies. Franga et al.⁷ reported only clinically significant bradycardia. They therefore reported the incidence of bradycardia to be only 17%. In contrast, Lehmann et al.⁹ labeled all individuals who had a record of a mean HR under 60 bpm during at least 1 day as bradycardic resulting in a reported incidence of 77% for individuals with cervical injuries. These differences clearly show the importance of using international accepted standards. According to the International Standards on Autonomic Function after SCI HR <60 bpm is defined as bradycardia² but others used the definition of <50 bpm stated by the Minnesota Code Classification System⁴. The American Heart Association's recomendations⁴⁴ state that bradycardia is defined as <60 bpm but, this rate is considered normal in healthy well-trained individuals. This will lead to an overestimation of the incidence of clinically significant bradycardia.

Kessler et al.¹⁷ use the term ‘level of spinal injury’ which makes it unclear if they refer to the neurological injury to the spinal cord or to the level of fracture to the spine. All other articles in this review use the term ‘spinal cord injury’ making it clearer that it is the neurological injury that is described.

Many drugs influence the electrical conduction of the heart. The arrhythmogenic effects of atropine and dopamine may explain the episodes of supraventricular tachycardia seen in patients with acute SCI.⁴⁵ These drugs were commonly used to manage bradycardia and hypotension in these patients.^9,12,46 Tricyclic antidepressants, commonly used to manage neuropathic pain in individuals with SCI,⁴⁷ may also influence the HR by inducing cardiac conduction delays. Some authors excluded participants who took medication that influences HR, had known diabetes mellitus, or had a history of cardiovascular disease prior to SCI. Four authors did not report on participant's medical history or medication.^7,8,13,14 This could mean that the arrhythmias recorded as associated with SCI were present before the injury or were adverse effects of pharmacological therapy. For this reason it may as well be advisable in future studies to use the International SCI Cardiovascular Function Basic Data Set⁴⁸ to make sure this information is standardized.

Most studies did not use continuous methods to record the HR or ECG. The authors using continuous measures^15,16 only recorded for short periods up to 1 hour. There is therefore a great risk of underestimating the incidence of both bradycardia and other arrhythmic events. Although never stated one may assume that most authors used the short-term ECG recording to determine the HR.

In this review, language bias could be a problem since all non-English articles were filtered out.

Conclusion

Bradycardia is seen frequently in the acute period after SCI among individuals with cervical injuries. The incidence of bradycardia peeks at 4–6 days after injury and is usually self-limiting after 3–5 weeks. In the chronic period after SCI, and at rest, cardiac arrhythmias are not more common among individuals with SCI than among able-bodied controls. When individuals with injuries to the spinal cord were introduced to exogenous stimulation, for example, tracheal suction, tracheal intubation, or penile vibro-stimulation, many reacted with bradycardia, and case-studies report episodes of autonomic dysreflexia and even cardiac arrest. There are still too little data in this area to produce a well-defined cut-off level for appropriate early cardiac intervention. We lack continuous and longitudinal data that records all arrhythmic events in individual patients from the acute period and through out the chronic phase.