Acute quadriplegia is a neurological emergency infrequently encountered in clinical practice. Localization of acute quadriplegia ranges from central nervous system, spinal cord, anterior horn cells, peripheral nerve, neuromuscular junction, and rarely muscles. Important etiologies of acute quadriplegia are cerebrovascular accident, trauma, demyelination, channelopathies, metabolic disturbances, and toxins. An astute physician can easily localize the neurological lesion, however, when there are confounding investigations particularly when the investigations are gold-standard for the etiologies under diagnostic consideration, it becomes difficult to attribute the cause of quadriplegia to a particular disease process. Then, the diagnosis is entirely clinical and depends on the type of clinical response obtained after the treatment of patients. We report a case of acute quadriplegia whose investigations favored both demyelination and metabolic derangement. Good clinical outcome was achieved when one of the etiologies was entertained for treatment for obvious reasons.
Keywords: Demyelination, flaccidity, Guillain–Barre syndrome, hypokalemia, quadriparesis
|How to cite this URL:|
Singh VP, Khullar J, Garg A, Vardani A. Acute quadriplegia: An interesting case with etiological and pathophysiological disparity. Indian J Med Spec [Epub ahead of print] [cited 2019 Aug 19]. Available from: http://www.ijms.in/preprintarticle.asp?id=261535
| Introduction|| |
There are various etiologies of hypokalemic paralysis, i.e., genetic, endocrine, gastrointestinal, and renal. The two major causes constituting acquired hypokalemic paralysis are renal tubular acidosis (RTA) and thyrotoxicosis. A common pathway for potassium loss is distal RTA in a variety of diseases, including connective tissue disorders such as Sjogren's syndrome (SS). SS is a chronic autoimmune inflammatory disorder, mainly affecting middle-aged females, having a prevalence ranging from 0.1% to 4.8%, and primarily involving exocrine glands. It can present either alone (primary SS [pSS]) or as an underlying connective tissue disorder (secondary SS). Very few case reports are described in literature with hypokalemic paralysis as a presenting feature of pSS.
Guillain–Barré syndrome (GBS) is an acute monophasic, immune-mediated, demyelinating polyneuropathy, usually caused by antecedent infection. Differentiating hypokalemic paralysis from GBS is extremely difficult clinically and is further compounded by the fact that electrophysiological differentiation based on nerve conduction (NC) studies can be challenging, especially in early stages. We present here a case of a patient of pSS presenting as hypokalemic acute quadriplegia initially and then re-presenting with similar complaints, but this time owing to an alternate diagnosis of GBS. To the best of our knowledge, this is the first case report of a patient presenting with recurrent episodes of acute flaccid quadriplegia with differing diagnosis of pSS associated hypokalemia and GBS, respectively.
| Case Report|| |
We are reporting a case of a 45-year-old Indian hypothyroid woman who was apparently well 1 day before admission, when at night, she observed dull aching, diffuse back pain followed by nausea and vomiting. She also developed weakness in both lower limbs which started on the same night after around 4 h of the onset of vomiting while being rushed to a local hospital in a four-wheeler. She was only weakly able to move her legs which started with her inability to move both feet and legs and later progressed to inability to move at all within the next 7–8 h. On the next day, in the morning, the patient complained of acute onset weakness in both arms which progressed to complete inability to move arms within the next 12 h. For the sake of brevity, this weakness was acute onset, painless, distal followed by proximal, rapidly progressive, symmetrical, and having no association with activity level. When the patient reported to us, she was fully conscious, hemodynamically stable, but with poor voluntary respiratory effort. Single-breath count was eight. There was no history of a similar episode in the past, trauma to head or upper spine, neck pain, fever, diarrhea, strenuous exercise, high carbohydrate diet, recent vaccination, exposure to heavy metals or pesticides, dog bite or snake bite, numbness or tingling sensation, bladder or bowel incontinence, difficulty in swallowing, diplopia, loss of vision, convulsions, or altered consciousness. Key findings of neurological examination done in an emergency room are depicted in [Table 1].
In view of acute flaccid quadriplegia and respiratory distress, she was immediately put on noninvasive ventilatory support through face mask and routine investigations, including arterial blood gases and electrolytes were obtained. Investigations done in the emergency room are enumerated in [Table 2]. A provisional working diagnosis of severe hypokalemia with metabolic acidosis leading to acute flaccid quadriplegia was inferred. Electrocardiogram done in the emergency room showed sinus tachycardia, flattening of T waves, and presence of U waves [Figure 1]. The patient was shifted to intensive care unit in view of impending respiratory arrest. Intravenous (IV) potassium chloride was started at 10 mEq/h. Patient's respiratory and neurological status improved appreciably in the next 24 h. Subsequent neurological examination revealed symmetric areflexia and inability to sense joint position and vibrations. Power in both upper and lower limbs improved dramatically.
|Figure 1: Electrocardiogram showing sinus tachycardia, flattening of T waves and presence of U waves|
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A clinical diagnosis of hypokalemia leading to flaccid quadriplegia was justified, but a history of backache, loss of posterior column sensations, and mute bilateral plantar reflexes were noted to be confounding elements from the etiological perspective. Vitamin B12 level was 1619 pg/ml (191–946). NC study was done on the next day of admission which revealed pure motor axonal demyelinating polyneuropathy with decreased amplitude of compound muscle action potential (CMAP) in both upper and lower limbs. Magnetic resonance imaging spine screening was unremarkable. Cerebrospinal fluid (CSF) examination showed 4 cells/mm3 (all lymphocytes), normal glucose levels, and raised protein levels of 68 mg/dl (15–45 mg/dl). Metabolic acidosis was investigated further as depicted in [Table 3] and calculations were done as per the values obtained in [Table 2] and [Table 3]. Blood anion gap was calculated as per the following equation:
Serum Na+ (138) + Serum K+ (1.6) − Serum Cl− (115) − Serum HCO3− (10.9) = 13.7 mmol/L (Normal range: 8–16 mmol/L).
As is evident, a normal anion gap/hypokalemic metabolic acidosis was found. Two most clinically important cause of a normal anion gap metabolic acidosis are diarrhea and RTA. Since the patient did not complain of diarrhea, RTA stood justified as the underlying phenomenon in this case. Nevertheless, a transtubular potassium gradient (TTKG) was obtained to objectively conclude the same. TTKG was calculated as per the following equation:
(Urine K+ (31.26)/Serum K+ [1.6])/(Urine osmolality (321)/serum osmolality (315)) = 19.33
(Normal range 8–9).
To further strengthen the case that the defect lies in the kidney, urine anion gap was calculated which was found to be positive:
(Urine Na+ (55) + Urine K+ (31.26) − Urine Cl− (73.9) = 12.36).
There are two types of RTA (Type 1 and Type 2) that cause hypokalemia. To ascertain which type was the underlying cause here, urine pH was obtained. A urine pH >5.3 is present in Type 1 RTA while Type 2 RTA exhibits variable urine pH. Thus, a positive urine anion gap with hyperchloremic hypokalemic metabolic acidosis along with high TTKG culminates in the penultimate diagnosis of distal (Type 1) RTA.
As part of a comprehensive workup, ancillary studies revealed the following. Serologies for anti-HIV antibodies, hepatitis B surface antigen, and anti-hepatitis C virus antibodies were negative. Urine analysis was negative for albumin and glucose. Ultrasonography of the abdomen was unremarkable. No calculus was noted in the urinary tract. There was no historical evidence of xerosis, however, Schirmer's test (normal value: >15 mm in 5 min) was mild to moderately positive (right eye: 8 mm and left eye: 12 mm). Antinuclear antibodies were undetectable; however, Anti SS-A/Ro and Anti SS-B/La were strongly positive. The patient was euthyroid on levothyroxine replacement therapy. Antithyroid peroxidase antibody was mildly raised 78 U/ml (<60 U/ml). A logically determinate diagnosis of SS with type 1 (distal) RTA with hypokalemia with demyelinating pure motor axonal polyneuropathy was made, and the patient was discharged in stable condition with advice to take oral potassium citrate. As the patient recovered completely with potassium replacement, the NC study finding of motor axonal polyneuropathy, though significant, was not incorporated in changing our treatment strategy. The patient did not follow-up regularly and reported to the emergency room only after 3 months with complaints of progressive weakness of both upper and lower limbs along with breathing difficulty developing rapidly over 2 days. Serum potassium levels in emergency were 4.3 mmol/L. NCV was repeated on priority basis which revealed demyelinating polyneuropathy with decreased amplitude of CMAP along with the absence of H-reflex. After interdisciplinary consultation with intensivist and neurologist, it was decided that the patient should be offered treatment with IV immunoglobulin. However, the patient decided against the offered treatment and was lost to follow-up.
| Discussion|| |
Acute neuromuscular paralysis is a commonly encountered neurological emergency. GBS and hypokalemia are frequently encountered causes of acute flaccid paralysis, whereas some other less frequent causes being hyperthyroidism, porphyria, botulism, diphtheria, Lyme disease, and various others. Common subtypes of GBS consist of acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy, which are differentiated based on clinicopathological and electrophysiological findings. At first presentation, her clinical profile suggested AIDP supported by NC studies and albuminocytological dissociation in CSF. However her NC findings are also explained by concomitant hypokalemia [Table 2]., The fact that she improved with potassium correction attributes her complaints to hypokalemia and not AIDP.
There are abundant causes of hypokalemia, caused by acquired or inherited metabolic disorders, either of muscle ion channels or renal tubules. All organs can be affected by low serum potassium levels, resulting in various clinical manifestations. The critical effect which potassium ion has on neuromuscular conduction, especially in the myocardium, is responsible for the majority of catastrophic patient outcomes that may result from hypokalemia. pSS is an autoimmune systemic disorder having manifestations mainly caused by a cell-mediated autoimmune destruction of exocrine glands. Extraglandular signs and symptoms of pSS result from a similar pathological mechanism affecting the kidneys, lungs, pancreas, liver, and the nervous system. The involvement of the kidneys in pSS has been a known fact since long and is one of the most commonly seen extraglandular manifestations. Ren et al. conducted a study on 130 patients and concluded that as much as 70% of patients with pSS had distal RTA.
Characteristic features of distal RTA result from inability of the kidneys to excrete hydrogen ions in the urine in a background of metabolic acidosis resulting in urine that is either alkaline or has inappropriately normal pH. This condition can be diagnosed by normal anion gap metabolic acidosis with a positive urine anion gap, as is present in our case. Hypokalemia is a result of renal potassium wasting. Although distal RTA is very commonly associated with SS as mentioned in the previous paragraph, it is usually asymptomatic and is not detected in majority of cases.
Combination of GBS and comorbid hypokalemia could be life-threatening and a challenge to treat, especially when it is part of an autoimmune disorder like pSS. The association of these two syndromes having a similar presentation but with different therapeutic strategies is very rare, and therefore, recognition of the same is consequential for clinical improvement.
A study conducted by Shah et al. to differentiate GBS from hypokalemic periodic paralysis on the basis of clinical features and laboratory tests concluded that positive family history, similar episodes of weakness in the past, low serum potassium during the episodes of weakness, and quick recovery within 24–72 h of potassium replacement helps differentiate between these two disorders.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
| Conclusion|| |
Hypokalemic paralysis often masquerades as GBS, leading to a diagnostic dilemma. Moreover, the occurrence of a GBS-like clinical phenotype in a known case of pSS with distal RTA with history of hypokalemic paralysis in recent past may make diagnosing coexisting GBS a therapeutic challenge. This article not only exemplifies this very rare association of pSS with GBS but also emphasizes the need for a high index of suspicion for GBS and the importance of taking a detailed history in any patient presenting with rapidly progressive weakness to the emergency room.
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Conflicts of interest
There are no conflicts of interest.
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Vivek Pal Singh,
Department of Internal Medicine, BLK Super Speciality Hospital, Pusa Road, New Delhi - 110 005
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3]