The Ataxic Gait: A Case of Vitamin B12 Deficiency Secondary to Malnutrition

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ESPR306
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History: 

9 year-old male presented with ataxic gait and dizziness that started four days prior to admission. Patient had recently been admitted to the pediatric ICU for dehydration, metabolic acidosis, and acute kidney injury, all of which had resolved by the time he was discharged, just two days prior to his re-admission. At the time of discharge from the PICU, he was noted to have dizziness and gait abnormalities, both of which failed to improve in the interim time period. These persistent abnormalities were recognized at his hospital follow up visit with his pediatrician and he was subsequently told to return to the ED. 

At the time of his second admission, it was noted that he had an unclear history of significant weight loss. Parents reported taking him to a nutritionist and reported that he had been worked up for "picky eating" and malnutrition. Similar to his mother, the patient had always been a picky eater, however these habits had worsened in the past year. Per father, the patient only ate raisins, almonds, strawberries, grapes, french fries, and oatmeal raisin bars. He previously enjoyed eating spinach, but had stopped within the past year, and never ate meat of any kind. He was taking a calcium supplement, due to lactose intolerance, and a multivitamin.  


Physical Exam: 

Vitals: Temp: 98.3, HR 95, RR 36, BP 110/69

General: alert, emaciated, in no acute distress 

HEENT: atraumatic, normocephalic, moist mucous membranes, PERRL, EOMI, no scleral icterus, no cervical lymphadenopathy 

Resp: no increased WOB, lungs CTA bilaterally, no wheezes, no rales, no rhonchi, symmetric air entry 

Cardiac: RRR, no murmurs, no rubs, no gallops, 2+ pulses in bilateral upper and lower extremities 

Abdomen: soft, non-tender, non-distended, normative bowel sounds, no masses, no organomegaly 

Neuro: alert, oriented x 3, normal repetition and recall, CN II through XII intact, 5/5 strength throughout, decreased proprioception and decreased sensation to light vibration in the feet bilaterally, 2+ symmetric brachioradialis DTR, absent patellar and achilles DTRs bilaterally, Babinski sign negative, normal muscle tone, no tremors, positive Romberg sign, gait is wide based and ataxic, nearly falls with heel to toe walking

Derm: brittle nails, small areas of hyperpigmentation on the dorsum of hands and scattered hyperpigmentation on extremities and face

 

Laboratory and Diagnostic Imaging: 

Measure 

Value 

Reference Range 

Glucose 

86

70 - 100 mg/dL 

BUN

9.0

7.0 - 18.0 mg/dL 

Creatinine 

0.5 

0.3 - 1.0 mg/dL 

Sodium 

137 

136 - 145 mEq/L 

Potassium 

4.4 

3.4 - 4.7 mEq/L 

Chloride 

96 

100 - 111 mEq/L 

CO2

27

22 - 29 mEq/L 

Calcium 

8.8

8.8 - 10.8 mg/dL 

Protein, Total 

6.2

6.2 - 8.1 g/dL 

Albumin 

3.4 

3.8 - 5.4 g/dL 

AST 

186 

15 - 40 U/L

ALT

101 

10 - 35 U/L 

Alkaline Phosphatase 

92

175 - 420 U/L 

Bilirubin, Total 

0.8

0.2 - 1.2 mg/dL 

Globulin 

2.8 

2.0 - 3.6 g/dL 

Albumin/Globulin Ratio 

1.2 

0.9 - 2.2 

Anion Gap 

14.0 

5.0 - 15.0 

 

Measure 

Value

Reference Range 

WBC

4.28 

4.29 - 11.20 x 10^3/uL

Hgb

11.2

10.6 - 13.3 g/dL 

Hematocrit 

31.0 

32.3 - 39.7 % 

Platelets 

334

203 - 368 x 10^3/uL

RBC

2.99

3.93 - 5.00 x 10^6/uL 

MCV

103.7 

75.2 - 86.9 fL 

MCH 

37.5 

24.8 - 29.4 pg 

MCHC

36.1

32.0 - 34.8 g/dL 

RDW

12

12 - 14 % 

MPV

11.0 

8.9 - 12.5 fL 

 

Measure 

Value

Reference Range 

Vitamin B12 

< 150 

211 - 911 pg/mL 

 

Measure 

Value

Reference Range 

Vitamin E (Alpha Tocopherol) 

9.5 

3.8 - 18.4 mg/L 

 

Measure 

Value

Reference Range 

Copper 

1.20 

0.80 - 1.80 

 

Measure 

Value

Reference Range 

Homocysteine

> 50.00

5.08 - 15.39 umol/L 

 

Measure 

Value

Reference Range 

Methylmalonic Acid, QN, S

1.08 


 

Measure 

Value

Reference Range 

Intrinsic Factor Blocking Antibody

Positive 

Negative 

 

MRI Brain: Suggested signal abnormality within the dorsal columns of the upper cervical spinal cord. No intracranial abnormality is detected. 

MRI Spine: Extensive, non-enhancing abnormal T2 prolongation involving the dorsal columns of the spinal cord from the upper cervical region through the lower thoracic (T9) region. 


Final Diagnosis: 

Subacute combined degeneration of the spinal cord, Vitamin B-12 Deficiency

 

Discussion: 

We describe a finding of subacute combined degeneration of the spinal cord secondary to vitamin B12 deficiency with macrocytosis in the absence of anemia. Vitamin B12 deficiency of any etiology is rare in the pediatric population. Severe complications of B12 deficiency are even more unlikely.

The child's parents had started daily multivitamin use months before this presentation, but these vitamins did not contain B12 and there was no clear explanation for the lack of anemia. This finding raises two key points. First, that B12 deficiency, even severe deficiency, can exist without its most common sequelae of anemia. Secondly, subacute combined degeneration can occur regardless of the existence of earlier, less severe symptoms and therefore one should have a high suspicion when assessing the ataxic child. 

The findings of non-enhancing abnormal T2 prolongation on brain and spine MRI involving the dorsal columns, also known as the inverted V sign, that represent subacute combined degeneration of the spinal cord are not pathognomonic for B12 deficiency. Rather, this finding can be seen in other nutritional deficiencies, specifically copper and vitamin E deficiency. It is therefore important to perform a complete and thorough malnutrition workup, to include cerulosplasmin and vitamin E, in these cases.

This patient was treated with intramuscular B12 (cyanocobalamin) at 1000mcg daily for the first 2 weeks, then transitioned to 1000mcg monthly. In follow up, about 1 month after discharge, his B12 had normalized, and the methylmalonic acid and homocysteine levels had also decreased. Interestingly, a repeat intrinsic factor at that time was negative. False positive intrinsic factor antibodies can occur in the setting of B12 supplementation. At follow up, his ambulation had been gradually improving and no longer required support to stand or walk. 

B12 deficiency, although rare in the pediatric population, can result in severe and long-lasting consequences. When presented with neurologic changes in a child with a history of poor nutrition, B12 deficiency should be included in the differential. 

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Associated Sessions

Inova Childrens Hospital
Inova Children's Hospital
Inova Children's Hospital

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