1

Introduction

Subacute combined degeneration (SCD) is a rapidly progressive myelopathy with a constellation of neurologic deficits, including progressive sensory abnormalities in the vibratory and proprioceptive domains, ascending paresthesias, gait ataxia, hyper- or hypo-reflexia, and, less commonly, motor weakness and loss of bowel and bladder control . SCD is a result of dorsal and lateral spinal cord demyelination . This form of myelopathy is secondary to a cobalamin or vitamin B12 deficiency, dietary insufficiency, malabsorption and/or, less commonly, excretion. Pernicious anemia, also known as autoimmune gastritis, is a common cause of vitamin B12 deficiency. Nitrous oxide (N ₂ O) exposure during recreational use or surgical intervention has also been reported to convert B12 to B12 analogues, which are then excreted in the urine, reducing B12 levels .

Up until now, much of the literature has presented the clinical manifestations of SCD primarily in the context of nitrous oxide (N ₂ O) abuse and exposure. Conversely, we report on a patient with a triple-insult SCD of the spinal cord, one insult secondary to non-compliance with B12 replacement therapy for pernicious anemia, one insult secondary to alcohol abuse, and one insult secondary to prolonged recreational use of nitrous oxide.

2

Case report

A 38-year-old man was triaged at a tertiary care setting for detoxification and alcohol withdrawal. He presented acutely with tremors, diaphoresis, insomnia, ataxia (progressive over the last three months), lower extremity paresthesias, decreased somatosensory perception, visual and auditory hallucinations, paranoia, and cognitive impairments. On questioning, he described copious alcohol consumption and nearly half a decade of N ₂ O abuse with a recent escalation. His medical history included pernicious anemia, for which he was intermittently compliant with B12 injections, generalized anxiety disorder, major depressive disorder, and social phobia. He was compliant with his psychiatric medications, but not with his psychotherapy, and had a suicide attempt two decades prior.

Neurological findings were significant for decreased vibratory perception in his feet bilaterally; decreased pinprick and temperature perception below his ankles bilaterally; dysmetria on finger-to-nose testing; impaired tandem walking; low clearance, wide-based gait; patellae hyper-reflexia; bilateral Babinski sign; and a positive Romberg test. His mental status examination revealed an illogical thought process, slow, halting speech, depression, anxiety, paranoia and delusions consistent with an acute, substance-induced psychotic disorder. Lab results revealed a macrocytic anemia (hemoglobin 11.2 g/dL), low B12 (193 pg/mL), elevated methylmalonic acid (324 nmol/L), hyperhomocysteinemia (213 μmol/L), and a mild transaminitis. His intrinsic factor blocking antibody test confirmed his pernicious anemia. The chest X-ray and a non-contrast CT of the patient’s brain were negative for acute processes. The patient was diagnosed with SCD.

Treatment included Librium, intramuscular B12 replacement therapy, Risperidone, and resumption of his prior psychiatric medication regimen. Five days into his hospitalization, he remained a fall risk, continued to display dysmetria on the finger-to-nose test, and still complained of visual hallucinations. However, he was more articulate, reported decreased sleep disturbances, and was stable for admission to acute inpatient rehabilitation.

Upon admission to the inpatient rehabilitation unit, evaluation his physical examination revealed a medium fall risk with a Berg balance score of 23/56, poor dynamic standing balance, and fair dynamic sitting balance. Contact guard assistance with straight cane was required for both bed mobility and transfers, ambulation, and stairway negotiation. For activities of daily living (ADL), he required supervision for bathing, toileting, toilet transfers, and dressing upper extremities; minimum assistance for bath transfers; and moderate assistance for dressing lower extremities. In terms of cognitive status, impairments included deficits in delayed recall, visuospatial and executive functions.

The patient underwent a three week acute inpatient rehabilitation course with intensive therapy consisting of two hours of physical therapy and one hour of occupational therapy each day five days per week. Physical therapy was used to retrain gait, ambulation, transfers, bed mobility and use of an assistive device and occupational therapy was used to retrain in ADLs, community reintegration, and cognitive training. The rehabilitation therapy helped the patient regained full sensory perception of his lower extremities and made impressive gains in ADLs, including independence during bathing, toileting, toilet transfers, bath transfers, bed mobility, dressing of upper/lower extremities and ambulation on even surfaces. We noted improvements in other areas of the assessment, however, his recovery was not complete. The patient was still a low fall risk status with a Berg balance of 45/56, showed impairments on dynamic balance testing, single leg activities, and ambulation on uneven surfaces and negotiation of ramps and stairs. Although his cognition appeared intact and thought process became more logical, his thought content was still impaired and contained thought insertions while his mood was frustrated, anxious, depressed and blunted. He was subsequently discharged to an inpatient substance abuse program.

2

Case report

A 38-year-old man was triaged at a tertiary care setting for detoxification and alcohol withdrawal. He presented acutely with tremors, diaphoresis, insomnia, ataxia (progressive over the last three months), lower extremity paresthesias, decreased somatosensory perception, visual and auditory hallucinations, paranoia, and cognitive impairments. On questioning, he described copious alcohol consumption and nearly half a decade of N ₂ O abuse with a recent escalation. His medical history included pernicious anemia, for which he was intermittently compliant with B12 injections, generalized anxiety disorder, major depressive disorder, and social phobia. He was compliant with his psychiatric medications, but not with his psychotherapy, and had a suicide attempt two decades prior.

Neurological findings were significant for decreased vibratory perception in his feet bilaterally; decreased pinprick and temperature perception below his ankles bilaterally; dysmetria on finger-to-nose testing; impaired tandem walking; low clearance, wide-based gait; patellae hyper-reflexia; bilateral Babinski sign; and a positive Romberg test. His mental status examination revealed an illogical thought process, slow, halting speech, depression, anxiety, paranoia and delusions consistent with an acute, substance-induced psychotic disorder. Lab results revealed a macrocytic anemia (hemoglobin 11.2 g/dL), low B12 (193 pg/mL), elevated methylmalonic acid (324 nmol/L), hyperhomocysteinemia (213 μmol/L), and a mild transaminitis. His intrinsic factor blocking antibody test confirmed his pernicious anemia. The chest X-ray and a non-contrast CT of the patient’s brain were negative for acute processes. The patient was diagnosed with SCD.

Treatment included Librium, intramuscular B12 replacement therapy, Risperidone, and resumption of his prior psychiatric medication regimen. Five days into his hospitalization, he remained a fall risk, continued to display dysmetria on the finger-to-nose test, and still complained of visual hallucinations. However, he was more articulate, reported decreased sleep disturbances, and was stable for admission to acute inpatient rehabilitation.

Upon admission to the inpatient rehabilitation unit, evaluation his physical examination revealed a medium fall risk with a Berg balance score of 23/56, poor dynamic standing balance, and fair dynamic sitting balance. Contact guard assistance with straight cane was required for both bed mobility and transfers, ambulation, and stairway negotiation. For activities of daily living (ADL), he required supervision for bathing, toileting, toilet transfers, and dressing upper extremities; minimum assistance for bath transfers; and moderate assistance for dressing lower extremities. In terms of cognitive status, impairments included deficits in delayed recall, visuospatial and executive functions.

The patient underwent a three week acute inpatient rehabilitation course with intensive therapy consisting of two hours of physical therapy and one hour of occupational therapy each day five days per week. Physical therapy was used to retrain gait, ambulation, transfers, bed mobility and use of an assistive device and occupational therapy was used to retrain in ADLs, community reintegration, and cognitive training. The rehabilitation therapy helped the patient regained full sensory perception of his lower extremities and made impressive gains in ADLs, including independence during bathing, toileting, toilet transfers, bath transfers, bed mobility, dressing of upper/lower extremities and ambulation on even surfaces. We noted improvements in other areas of the assessment, however, his recovery was not complete. The patient was still a low fall risk status with a Berg balance of 45/56, showed impairments on dynamic balance testing, single leg activities, and ambulation on uneven surfaces and negotiation of ramps and stairs. Although his cognition appeared intact and thought process became more logical, his thought content was still impaired and contained thought insertions while his mood was frustrated, anxious, depressed and blunted. He was subsequently discharged to an inpatient substance abuse program.