Intention tremor

Disorders of the human cerebellum result in three types of abnormalities. The first is hypotonia or reduced muscle tone. Another includes abnormalities in the execution of voluntary movements or ataxia (defective muscular coordination). The third type of muscular malfunction is intention tremors. These tremors differ from the resting tremors of Parkinson s disease in that they occur during a movement and are most pronounced at the end of the movement when the patient attempts to terminate it. 

All reflexes were abolished, and pupil size varied. All patients survived the first coma and became fully conscious however, one patient died in coma several days later due to extensive liver necrosis (Piersol et al. 1933). Mild cerebellar damage (instability of gait, intentional tremor) was observed in one patient, but reversed to normal in two weeks (Storms 1973). 

Several types of abnormal movement are recognized. Tremor consists of a rhythmic oscillatory movement around a joint and is best characterized by its relation to activity. Tremor at rest is characteristic of parkinsonism, when it is often associated with rigidity and an impairment of voluntary activity. Tremor may occur during maintenance of sustained posture (postural tremor) or during movement (intention tremor). A conspicuous postural tremor is the cardinal feature of benign essential or familial tremor. Intention tremor occurs in patients with a lesion of the brain stem or cerebellum, especially when the superior cerebellar peduncle is involved it may also occur as a manifestation of toxicity from alcohol or certain other drugs. 

Intention tremor is present during movement but not at rest sometimes it occurs as a toxic manifestation of alcohol or drugs such as phenytoin. Withdrawal or reduction in dosage provides dramatic relief. There is no satisfactory pharmacologic treatment for intention tremor due to other neurologic disorders. 

Chronic poisoning from inhalation of mercury vapor results in a classic triad of tremor, neuropsychiatric disturbance, and gingivostomatitis. The tremor usually begins as a fine intention tremor of the hands, but the face may also be involved,... 

Persistent acute body zinc loss has resulted in many symptoms in addition to taste and smell dysfunction if losses continue at significant levels for periods of 14 days or more. These symptoms Include mental confusion, cerebellar dysfunction, including intention tremor and ataxia, an erythrematous, Intracrural rash, buccal epithelial lesions and ulcers, and acute toxic psychosis (,6). The altered mental state of these patients can be related to the rapid depletion of the relatively high zinc content in the limbic system of the brain (16.17), demonstrating that zinc can cross the blood brain barrier bidirectionally, dependent upon the gradient, and that it can be readily mobilized from brain tissue. 

Acute phase Sudden deterioration to an acute encephalopathy occurs over a period ranging from several hours to 1-2 days. Patients develop dysarthria, severe locomotor disturbances such as ataxia, difficulty in walking, intention tremor, myoclonic jerks (especially of the upper limbs, face, and trunk), incontinence due to loss of sphincter control, hyper-reflexia, and sometimes generalized convulsions. The patient may be confused, disoriented, and agitated. Excitation, hallucinations, delirium, and fluctuations of mental alertness, ranging from dizziness to loss of consciousness and coma, can occur. In about 7-9% of cases the outcome is fatal,... 

A 58-year-old woman with end-stage renal insufficiency secondary to diabetic nephropathy developed abdominal wall cellulitis 4 days after insertion of a peritoneal dialysis catheter. She was given vancomycin, cefepime, and metronidazole in reduced doses (doses not stated) and 2 days later developed dysarthria, an intention tremor, dysmetria, and dysdiadochokinesia. Routine biochemical tests were unchanged and a CT scan of the brain was unremarkable, but an MRI scan showed cerebral and cerebellar atrophy with multifocal ischemic glial lesions. Metronidazole was withdrawn and 2 days later her symptoms and signs had completely resolved. 

Neuroleptic-induced parkinsonian side effects are characterized by the triad of tremor, muscle stiffness, and slowness of motion. For the most part, these physical indicators are relatively easy to identify. The tremor, which is somewhat coarse and may include classic "pill-rolling," is worse at rest, and is distinguishable from the fine, intention tremor of lithium. Muscle stiffness or rigidity is notable for the increased resistance to passive movement ("cogwheeling"). 

Human 1-41 yr 15.3 yr mean 0.026b M (increased frequency of mild intention tremors with weight load) Fawer et al. 1983 ELEM... 

Hagerman RJ, Leehey M, Heinrichs W, Tassone F,-Wilson R, Wfils J, et al. Intention tremor, parkinsonism, and generalized brain atrophy in male carriers of fragile X. Neurology 2001 57 127-30. 

Workers in the chloralkaH industry were formerly occupationally exposed to mercury vapour. An increased frequency of intention tremors (time weighted average (TWA) of 0.026 mg/m ) was found in workers who inhaled mercury vapour for an average of 26 years. Neurobehavioural effects (motor speed, visual scanning, co-ordination and concentration) were affected in individuals with a TWA of 0.014 mg/m while workers exposed to an average of... 

Hunter and Russell 1954) - subsequently became known as Minamata disease " (see below), and is normally characterized by an extreme latent period of several months, or even years. These conditions start with nonspecific symptoms such as intention tremor, parenthesis, nausea, blurred vision, malaise, sensorial impairments and auditory disturbances, followed by ataxia and massive damage of the CNS. Characteristic is a concentric narrowing of the visual field (Harada 1995). At autopsy, the most conspicuous destructive lesion in the cerebrum was found in the anterior portions of the calcarine cortex. Less severe but similar lesions may be found in the post-central, pre-central and temporal transverse cortices. Secondary degeneration from primary lesions may be seen in cases with long-term survival. In the cerebellum, pathological changes occur deep in the... 

Early stages feature a fine intention tremor of the fingers, but involvement of the face and progression to choreiform movements of the limbs may occur. 

Brice, J. and L. McLellan, Suppression of intention tremor by contingent deep-brain stimulation. Lancet, 1980,1 1221-1222. 

---