Lhermitte’s sign and vitamin B12 deficiency: case report

ABSTRACT CONTEXT AND OBJECTIVE: Lhermitte’s sign, a classical neurological sign, is a rare manifestation of vitamin B12 deficiency. The aim here was to report on a case of an elderly patient with vitamin B12 deficiency whose first clinical manifestation was the presence of Lhermitte’s sign. CASE REPORT: We describe an elderly patient with vitamin B12 deficiency who presented cognitive dysfunction, peripheral polyneuropathy and sensory ataxia, and whose first clinical manifestation was the presence of Lhermitte’s sign. This sign is one of the rarest manifestations of vitamin B12 deficiency.


INTRODUCTION
Vitamin B12 deficiency is found in 15% of the geriatric population.The manifestations are hematological, gastrointestinal and neuropsychiatric. 1,2The neurological manifestation consists of subacute combined degeneration of the spinal cord that is clinically characterized by sensory ataxia, peripheral neuropathy, cognitive dysfunction and optic neuropathy. 1,2hermitte's sign, also known as the barber's shop sign, is more properly a symptom than a sign, and is described by patients as an electriclike sensation induced by forward flexion of the head. 3,4It was originally described by Marie and Chatelin in 1917, and one year later by Babinski and Dubois.6][7][8] One patient described it as follows: "When I bent my head, I felt a violent shock in my neck and a pain like an electric current running through my whole body, from the neck down the vertebral column into the feet". 84][5][6][7][8] To estimate the validity and frequency of this sign for diagnosing myelopathy, we conducted a systematic review of the literature, including the following databases: DotLib -OVID; DotLib -OVID (Lippincott); EBS-CO Biomedical Reference Collection; EBSCO -MedicLatina; EBSCO -Medical Literature Analysis and Retrieval System Online (Medline); ProQuest -Medical Library; PubMed; Cochrane Library; and Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs).0][11][12][13][14][15][16][17][18] Only two studies measured the diagnostic accuracy of Lhermitte's sign, and they found that its sensitivity is markedly poor, ranging from 3 to 17%. 19,20One of these studies also found that it presented good specificity (97%) for nonspecific compressive myelopathy. 20e describe an elderly patient with vitamin B12 deficiency who initially presented with Lhermitte's sign.

CASE REPORT
A 68-year-old man came to the outpatient clinic reporting an electric shock-like sensation through his neck and spreading down his spine and lower limbs that was triggered by neck flexion.This was associated with paresthesia in his toes, gait disorders, progressive memory loss and slow thinking that had also been noticed over a three-month period preceding the appointment.
The examination on the patient revealed cognitive dysfunction (mini-mental state examination, MMSE = 18/30), glove and stocking hypoesthesia, proprioception loss in the lower limbs, wide-based gait and Romberg's and Lhermitte's signs.The cranial nerves, motor strength, muscle tone, coordination, muscle strength reflexes and plantar reflex were normal.Laboratory investigation revealed macrocystic anemia.The creatinine levels, liver function, blood electrolytes, coagulation profile and thyroid-stimulating hormone (TSH) were normal.The erythrocyte sedimentation rate (ESR) was 54 mm/h.The serum vitamin B12 level was 51 pg/ml (normal range = 200-900 pg/ml).The cerebrospinal fluid was normal with negative venereal disease research laboratory (VDRL) and anti-human immunodeficiency virus (anti-HIV) antibodies.A hiatus hernia and a gastric polyp were seen on gastroscopy.Histopathology was negative for malignancies.Nerve conduction evaluation revealed axonal sensory-motor peripheral polyneuropathy.Brain and spinal cord magnetic resonance imaging (MRI) were normal.
Intramuscular vitamin B12 therapy was started (5000 IU, monthly).Complete recovery was progressively achieved over a 12-month period.

DISCUSSION
The neurological manifestations of vitamin B12 deficiency include peripheral and cranial nerve neuropathy and spinal cord and brain syndromes. 1,2Healton et al. found neurological signs in 74% of 143 vitamin B12 deficiency patients.Their findings were peripheral neuropathy (25%) myelopathy (12%), a combination of both of these (41%), neuropsychiatric dysfunction (8.1%) and visual deficits (0.5%). 1 The presence of Lhermitte's sign in patients with vitamin B12 deficiency has been previously described, [3][4][5][6][7] and it is characterized by a sensation of electrical lightning discharge, with paresthesia experienced through the spine, legs and sometimes arms, caused by neck flexion. 8he pathophysiology of Lhermitte's sign was classically described as related to the stretching of the hyperexcitable demyelinated dorsal column of the spinal cord, particularly at the cervical level, thereby triggering an electric shock-like sensation. 4,8Today, hyperexcitability is still regarded as the main pathophysiological mechanism.Moreover, from an  etiological standpoint, in the original paper by Lhermitte, the shock-like sensations were attributed to medullar lesions due to demyelination or trauma of the dorsal column. 1,4,8,21ince then, although the presence of Lhermitte's sign remains associated with such causes, particularly multiple sclerosis, several other causes have been described, including cervical disc hernia, cervical spondylosis, tumors, radiation myelopathy, herpes zoster, arachnoiditis, Behcet's disease, atlantoaxial subluxation, and non-lesional disorders such as hyperexcitability of the ascending sensory neurons of the posterior column due to toxic causes. 4,8,22][23] Lhermitte's sign is rare in patients with vitamin B12 deficiency and may improve with specific therapy.